This is a great 15 page pdf that came with an eBay purchased I converted it to text to paste here, the problem section with deficiency is great for new growers, if you would like the pdf just send me a pm with your email.
Emerald Hydroponics FAQ
What is Hydroponics?
Hydroponics is the method of growing plants using a soilless media which
could include a wide variety of examples like: gravel, peat, vermiculite
Perlite, old rubber tires, rockwool, and expanded clay aggregates. The
minerals that the plant needs are dissolved into the water which is then
watered directly to the plants. So, in short instead of the plants searching
throughout the soil for their minerals they draw them directly from the water
that they are being fed.
What is pH?
A measure of the acidity or alkalinity of a solution, numerically equal to 7
for neutral solutions, increasing with increasing alkalinity and decreasing
with increasing acidity. We recommend that you keep your solution at about
6.5 because that is the point at which the nutrients are the most soluble.
What is PPM?
PPM is very easily defined as Parts Per Million and can be used as the
measurement of a number of different things. More commonly in the
hydroponics world, this measurement is used to measure the amount of
Total Dissolved Solids in your nutrient solution or how much Co2 is in your
atmosphere.
What is the difference between High Pressure Sodium and Metal
Halide?
The difference between these two types of HID (High Intensity Discharge)
lights is the color spectrum that is emitted from each. The High Pressure
Sodium bulb emits light that is concentrated in the red to yellow side of the
spectrum and are weak in the blue-violet end. While the Metal Halide bulb
emits light that is very balanced and contains all the energy peaks at
wavelengths of the visible spectrum. Visually the Sodium bulbs will appear
very yellow-orange and the Halide bulbs will appear more blue-white in
color.
Should I use Sodium or Halide?
The Halide lights have a very balanced spectrum and are excellent for
vegetative growth or leafy plants like lettuce and basil. The Halide lights
produce between 65-115 lumens per watt which is a measure of the
efficiency of the bulb, or how much light you are producing for the amount
of electricity you are using. The Sodium lights produce light that is very
bright and concentrated on the yellow to red side of the color spectrum.
This color is not as balanced as the Halide but makes up for the lacking of a
balanced spectrum in the amount of light given off by the bulb. The Sodium
bulbs produce between 97 to 150 lumens per watt which is much higher
than the Halide bulbs. The Sodium bulbs are superior in life expectancy and
efficiency while the Halides a superior in spectral distribution so your
decision will be based on what is more important to you.
Why do people use Metal Halides for vegetative growth and High
Pressure Sodium's for flowering?
Many people switch between bulbs for different stages of growth for a
couple of reasons. First of all, Sodium bulbs have been known to make
some plants grow leggy and stretched out because of the yellow to red
spectrum that they give off. Metal Halides tend to keep these plants tighter
with less space between internodes. So some growers use the Metal Halide
lights during vegetative growth to keep the structural growth of the plant
nice and tight. But they switch to Sodium lights when the plants begin to
flower because the Sodium lights produce so much more light than the
Halides. Even though the Sodium's do not have as good a spectrum as the
Halides the intense light that is put off by the Sodium's aids in flower
development and fruit set. Do not be fooled though, you can use either
light throughout the life of a plant and get excellent results.
What size light should I purchase?
The first thing you need to do is figure out what kind of square footage
you are dealing with. Do not just figure for the whole room figure out what
the plant area is that you need to cover and multiply length x width to get
the square footage. Now, you will want to try and achieve at least 30 watts
per square foot. So if you have a 4 x 4 area which is 16 square feet and
you multiply by 30 watts, you get 480 watts. So for a 4 x 4 area you will
need to use at least a 430 watt light. Remember though that the amount of
light required will depend on the plants because some plants like lots of light
and some like low levels of light.
Do I need a ballast?
Yes. A ballast is required to start the lamp and to increase the voltage
required to run the lamp. The ballast is responsible for starting the lamps by
providing a high, fast charge of electricity. After the bulb lights, the range of
voltage and current are controlled by the transformer which is why the bulbs
operate so efficiently.
Are HID lights efficient?
Yes, very efficient compared to standard incandescent bulbs found in your
house. For example one 1000 watt sodium bulb produces as much light as
about 87 standard 100 watt incandescent bulbs.
Can I interchange bulbs between systems?
No. You should never interchange bulbs between systems unless they are
specifically made to do so. Lots of people ask if they can use a 250 watt
bulb in a 400 watt system and the answer is definitely not. You could put
yourself at risk by doing something like this because the bulb could become
unstable and explode. You should also never put Halide bulbs in a High
Pressure Sodium system because the ballast's are only meant to run the
type of bulb they are rated for and a Halide bulb in a Sodium system could
overheat and explode also. There are conversion bulbs manufactured that
are High Pressure Sodium bulbs that are meant to run off of a Halide
ballast. But once again only put the bulb in a system it is rated for.
Do these lights require any special wiring?
No. All systems are completely wired and just need to be plugged into
any grounded wall outlet. Custom voltages can be built into ballast's per
customer request (208v, 240v, 277v). Do not attempt to change the
voltage of the ballast unless you are an experienced electrician. Connecting
the wrong wires could result in a fried ballast or bulb, and even worse a fire.
What kind of plants can be grown using hydroponics?
Almost any type of plant can be grown using hydroponics some are just
more delicate than others. Usually if you can produce ideal environmental
conditions the hydroponic plants will be far superior to plants from the same
stock grown in soil.
How often should I change my nutrient solution?
There really isn't an amount of time that should be used to determine how
often you should change your solution. A good rule of thumb to follow first
of all is to top your reservoir off with fresh water without any nutrient
added. This is because you will lose water to evaporation and plant uptake
but the strength of the solution does not necessarily drop with the level of
the water. So, in some cases as the reservoir water level drops the solution
concentration actually goes up or gets stronger. So, add only fresh water
and then adjust your pH accordingly. Try and keep a record of how much
water you are putting in the reservoir to top it off and once the amount of
water added equals half of the reservoir capacity it is time to change the
solution and rinse the reservoir and growing medium. For example if you
have a 20 gallon reservoir and over the course of 12 days you have added
10 gallons of water, then it is time to change your solution.
Can I transfer plants from soil to hydroponics?
Yes, you can all you need to do is wash the roots of the plant by dipping
in water and try to remove as much of the soil matter as possible. Be very
careful with the delicate roots so the plant doesn't go into too much
transplant shock. After the roots are somewhat clean go ahead and pot the
plant in any of your favorite hydroponic media and begin a standard
watering regimen with a touch of B-1 in the solution for a week or so to aid
in the recovery from transplanting.
Do plants grown using hydroponics taste better than plants grown in
soil?
Quite often this is the case because the plants grown utilizing hydroponics
have all the essential nutrients readily available to the plant. In soil the
important micro nutrients are often locked away in the soil where the plants
cannot take full advantage of these minerals. That is why hydroponics is
superior because the grower has complete control over what minerals the
plants are feeding on and in what quantities. This advantage over soil often
produces produce that is far superior in taste, color, size, and nutritional
value.
How often do I need to water my plants?
Watering will all depend on the type of plants being grown, the size of
those plants, and what type of medium you are using. As you know plants
are very particular about being over or under-watered so this is an
important question. First you need to determine if the medium you are
using is absorbent or repellant. If you are using Rockwool you are dealing
with an absorbent medium while Hydroton is a good example of a repellent
medium that doesn't hold a lot of water. You want your medium to be moist
but not drenched and you want your medium to dry out somewhat between
waterings. So, if you watch your plants before and after waterings it will be
very easy to tell if you are watering too much or too little. If your plants wilt
before you water, but perk up immediately after watering, you may want to
water a little more often. If your plants wilt just after watering than you are
watering too much, and you should allot a little more time in between
waterings. A good general rule of thumb is to start plants being watered
about 2 to 3 times a day and increase as plants show signs of needing
water.
What Co2 system is right for me?
The deciding factor in this problem is almost always heat. Co2
generators burn either natural gas or propane to produce Co2. The
combustion of these fuels produces Co2 as a byproduct. Now the downfall of
the generators is the heat that is produced in the process. While the
generators are on they can raise temperatures in a grow room considerably.
The nice thing about generators is the availabilty of propane or natural gas
and the price of gas is considerably less than Co2. On the other hand, Co2
regulators are hooked up to Co2 tanks and regulate the amount of gas
being emitted through the use of a timer and a flowmeter. You set the
Cubic Feet per Hour (CFH) on the regulator and open the solenoid long
enough to charge the room with Co2 up to the desired PPM using the timer
to control the intervals. Co2 regulator type systems do not produce any
heat at all but are more expensive to maintain then the generator systems
since the price of Co2 is much higher than propane or natural gas.
What is the difference between Miracle-Gro and other commercially
available fertilizers and hydroponics nutrients?
Most of the fertilizers readily available are very general purpose mixes
that do not work well for all types of plants. The nutrients that we sell are
made specifically for plants grown in hydroponics systems that utilize sterile
growing mediums. Most commercially available fertilizers are meant for
fertilizing plants grown in soil and do not contain all the necessary trace
elements. Our fertilizers contain all those trace elements, and are also made
to be very soluble so that the plants can easily uptake the nutrients from the
watering solution. Those other fertilizers will work to grow plants but they
cannot compare to the results you will experience with our nutrients. Most
commercially available fertilizers are like junk food for your plants giving you
quick results that do not last very long.
What is the desired temperature range for the nutrient solution?
The optimal temperature of the nutrient solution should be in the range of
65 to 75 degrees Fahrenheit. Letting water stand uncovered in a container
overnight will help dissipate any chlorine in the water before you add it to
the reservoir.
How much electricity will I save running a grow light 240 volt?
There is no energy savings from running your lights at 240 volts. That is
a misconception that many people have. The main advantage is the fact
that you can run more lights on one electrical circuit. For example if you run
a 20 amp 120 volt circuit, you can only run two 1000 watt lights on that
circuit. If you were to wire the circuit up for 240 volts you can run four 1000
watt lights on that circuit. This makes for a lot less wiring but does not save
you on your electricity bill because each light still uses the same amount of
watts.
How can I tell if my seeds are viable?
This can be accomplished by presoaking your seeds. Fill a shot glass with
distilled water and place your seeds in it. After 24 hours the viable seeds
should have sank to the bottom. Those still floating are most likely not
viable and will not germinate.
Element Description of Deficiency and Toxicity
N Nitrogen: Deficiency: Plants will exhibit lack of vigor as older leaves
become yellow (chlorotic) from lack of chlorophyll. Chlorosis will
eventually spread throughout the plant. Stems, petioles and lower
leaf surfaces may turn purple.
Toxicity: Leaves are often dark green and in the early stages
abundant with foliage. If excess is severe, leaves will dry and
begin to fall off. Root system will remain under developed or
deteriorate after time. Fruit and flower set will be inhibited or
deformed.
P Phosphorus: Deficiency: Plants are stunted and older leaves often dark dull
green in color. Stems and leafstalk may turn purple. Plant
maturity is often delayed.
Toxicity: This condition is rare and usually buffered by pH
limitations. Excess phosphorus can interfere with the availability of
copper and zinc.
K Potassium: Deficiency: Older leaves are initially chlorotic but soon develop
dark necrotic lesions (dead tissue). First apparent on the tips and
margins of the leaves. Stem and branches may become weak and
easily broken.
Toxicity: Usually not absorbed excessively by plants. Excess
potassium can aggravate the uptake of magnesium, manganese,
zinc and iron.
S Sulfur: Deficiency: The initial symptoms are the yellowing of the entire
leaf including veins usually starting with the younger leaves. Leaf
tips may yellow and curl downward.
Toxicity: Leaf size will be reduced and overall growth will be
stunted. Leaves yellowing or scorched at edges.
Mg Magnesium: Deficiency: The older leaves will be the first to develop
interveinal chlorosis. Starting at leaf margin or tip and progressing
inward between the veins.
Toxicity: Magnesium toxicity are rare and not generally exhibited
visibly.
Ca Calcium: Deficiency: Young leaves are affected first and become small and
distorted or chlorotic with irregular margins, spotting or necrotic
areas. Bud development is inhibited and roots may be
underdeveloped or die back. Fruit may be stunted or deformed.
Toxicity: Difficult to distinguish visually. May precipitate with
sulfur in solution and cause clouding or residue in tank.
Fe Iron: Deficiency: Pronounced interveinal chlorosis similar to that cased
by magnesium deficiency but on the younger leaves.
Toxicity: Excess accumulation is rare but could cause bronzing or
tiny brown spots on leaf surface.
Mn Manganese: Deficiency: Interveinal chlorosis on younger or older leaves
followed by necrotic lesions or leaf shedding. Restricted growth
and failure to mature normally can also result.
Toxicity: Chlorosis, or blotchy leaf tissue due to insufficient
chlorophyll synthesis. Growth rate will slow and vigor will decline.
Cl Chlorine: Deficiency: Wilted chlorotic leaves become bronze in color. Roots
become stunted and thickened near tips.
Toxicity: Burning of leaf tip or margins. Bronzing, yellowing and
leaf splitting. Reduced leaf size and lower growth rate.
B Boron: Deficiency: Stem and root tips often die. Root tips often become
swollen and discolored. Internal tissues may rot and become host
to fungal disease. Leaves show various symptoms which include
drying, thickening, distorting, wilting, and chlorotic or necrotic
spotting.
Toxicity: Yellowing of leaf tip followed by necrosis of the leaves
beginning at tips or margins and progressing inward. Some plants
are especially sensitive to boron accumulation.
Zn Zinc: Deficiency: Chlorosis may accompany reduction of leaf size and a
shortening between internodes. Leaf margins are often distorted
or wrinkled.
Toxicity: Zinc in excess is extremely toxic and will cause rapid
death. Excess zinc interferes with iron causing chlorosis from iron
deficiency.
Cu Copper: Deficiency: Young leaves often become dark green and twisted.
They may die back or just exhibit necrotic spots. Growth and yield
will be deficient as well.
Toxicity: Reduced growth followed by symptoms of iron chlorosis,
stunting, reduced branching, abnormal darkening and thickening of
roots. This element is essential but extremely toxic in excess.
Mo Molybdenum
eficiency: Often interveinal chlorosis which occurs first on older
leaves, then progressing to the entire plant. Developing severely
twisted younger leaves which eventually die.
Toxicity: Excess may cause discoloration of leaves depending on
plant species. This condition is rare but could occur from
accumulation by continuous application. Used by the plant in very
small quantities.
Ca Calcium: Deficiency: Young leaves are affected first and become small and
distorted or chlorotic with irregular margins, spotting or necrotic
areas. Bud development is inhibited and roots may be
underdeveloped or die back. Fruit may be stunted or deformed.
Toxicity: Difficult to distinguish visually. May precipitate with
sulfur in solution and cause clouding or residue in tank.
Fe Iron: Deficiency: Pronounced interveinal chlorosis similar to that cased
by magnesium deficiency but on the younger leaves.
Toxicity: Excess accumulation is rare but could cause bronzing or
tiny brown spots on leaf surface.
Mn Manganese: Deficiency: Interveinal chlorosis on younger or older leaves
followed by necrotic lesions or leaf shedding. Restricted growth
and failure to mature normally can also result.
Toxicity: Chlorosis, or blotchy leaf tissue due to insufficient
chlorophyll synthesis. Growth rate will slow and vigor will decline.
Cl Chlorine: Deficiency: Wilted chlorotic leaves become bronze in color. Roots
become stunted and thickened near tips.
Toxicity: Burning of leaf tip or margins. Bronzing, yellowing and
leaf splitting. Reduced leaf size and lower growth rate.
B Boron: Deficiency: Stem and root tips often die. Root tips often become
swollen and discolored. Internal tissues may rot and become host
to fungal disease. Leaves show various symptoms which include
drying, thickening, distorting, wilting, and chlorotic or necrotic
spotting.
Toxicity: Yellowing of leaf tip followed by necrosis of the leaves
beginning at tips or margins and progressing inward. Some plants
are especially sensitive to boron accumulation.
Zn Zinc: Deficiency: Chlorosis may accompany reduction of leaf size and a
shortening between internodes. Leaf margins are often distorted
or wrinkled.
Toxicity: Zinc in excess is extremely toxic and will cause rapid
death. Excess zinc interferes with iron causing chlorosis from iron
deficiency.
Cu Copper: Deficiency: Young leaves often become dark green and twisted.
They may die back or just exhibit necrotic spots. Growth and yield
will be deficient as well.
Toxicity: Reduced growth followed by symptoms of iron chlorosis,
stunting, reduced branching, abnormal darkening and thickening of
roots. This element is essential but extremely toxic in excess.
Mo Molybdenumeficiency: Often interveinal chlorosis which occurs first on older
leaves, then progressing to the entire plant. Developing severely
twisted younger leaves which eventually die.
Toxicity: Excess may cause discoloration of leaves depending on
plant species. This condition is rare but could occur from
accumulation by continuous application. Used by the plant in very
small quantities.
This page has been designed to help answer the important questions
beginning growers might have when just getting started in hydroponics. A
lot of these concepts are connected to each other. Follow the links and put
the pieces of this growing puzzle together.
The more you know, the easier it is to grow!
Carbon Dioxide
During photosynthesis, plants use carbon dioxide (CO2), light, and hydrogen
(usually water) to produce carbohydrates, which is a source of
food. Oxygen is given off in this process as a by-product. Light is a key
variable in photosynthesis.
Conductivity
Measuring nutrient solution strength is a relatively simple process. However, the
electronic devices manufactured to achieve this task are quite sophisticated and use
the latest microprocessor technology. To understand how these devices work, you
have to know that pure water doesnt conduct electricity. But as salts are dissolved
into the pure water, electricity begins to be conducted. An electrical current will
begin to flow when live electrodes are placed into the solution. The more salts that
are dissolved, the stronger the salt solution and, correspondingly, the more
electrical current that will flow. This current flow is connected to special electronic
circuitry that allows the grower to determine the resultant strength of the nutrient
solution.
The scale used to measure nutrient strength is electrical conductivity (EC) or
conductivity factor (CF). The CF scale is most commonly used in hydroponics. It
spans from 0 to more than 100 CF units. The part of the scale generally used by
home hydroponic gardeners spans 0-100 CF units. The part of the scale generally
used by commercial or large-scale hydroponic growers is from 2 to 4 CF. (strength
for growing watercress and some fancy lettuce) to as high as approximately 35 CF
for fruits, berries, and ornamental trees. Higher CF values are used by experienced
commercial growers to obtain special plant responses and for many of the modern
hybrid crops, such as tomatoes and some peppers. Most other plant types fall
between these two figures and the majority is grown at 13-25 CF.
--Rob Smith
Germination
When a seed first begins to grow, it is germinating. Seeds are germinated in
a growing medium, such as perlite. Several factors are involved in this
process. First, the seed must be active--and alive--and not in dormancy.
Most seeds have a specific temperature range that must be achieved.
Moisture and oxygen must be present. And, for some seeds, specified levels
of light or darkness must be met. Check the specifications of seeds to see
their germination requirements.
The first two leaves that sprout from a seed are called the seed leaves, or
cotyledons. These are not the true leaves of a plant. The seed develops
these first leaves to serve as a starting food source for the young,
developing plant.
Growing Medium
Soil is never used in hydroponic growing. Some systems have the ability to
support the growing plants, allowing the bare roots to have maximum
exposure to the nutrient solution. In other systems, the roots are supported
by a growing medium. Some types of media also aid in moisture and
nutrient retention. Different media are better suited to specific plants and
systems. It is best to research all of your options and to get some
recommendations for systems and media before making investing in or
building an operation. Popular growing media include:
Composted bark. It is usually organic and can be used for seed germination.
Expanded clay. Pellets are baked in a very hot oven, which causes them to expand, creating a porous end
product.
Gravel. Any type can be used. However, gravel can add minerals to nutrient. Always make sure it is
clean.
Oasis. This artificial, foam-based material is commonly known from its use as an arrangement base in the
floral industry.
Peat moss. This medium is carbonized and compressed vegetable matter that has been partially
decomposed.
Perlite. Volcanic glass is mined from lava flows and heated in furnaces to a high temperature, causing the
small amount of moisture inside to expand. This converts the hard glass into small, sponge-like kernels.
Pumice. This is a glassy material that is formed by volcanic activity. Pumice is lightweight due to its large
number of cavities produced by the expulsion of water vapor at a high temperature as lava surfaces.
Rockwool. This is created by melting rock at a high temperature and then spinning it into fibers.
Sand. This medium varies in composition and is usually used in conjunction with another medium.
Vermiculite. Similar to perlite except that it has a relatively high cation exchange capacity--meaning it
can hold nutrients for later use.
There are a number of other materials that can (and are) used as growing
media. Hydroponic gardeners tend to be an innovative and experimental
group.
Hydroponic Systems
The apparatuses used in hydroponic growing are many and varied. There are
two basic divisions between systems: media-based and water culture. Also,
systems can be either active or passive. Active systems use pumps and
usually timers and other electronic gadgets to run and monitor the
operation. Passive systems may also incorporate any number of gadgets.
However, they to not use pumps and may rely on the use of a wicking agent
to draw nutrient to the roots.
Media-based systems--as their name implies--use some form of growing
medium. Some popular media-based systems include ebb-and-flow (also
called flood-and-drain), run-to-waste, drip-feed (or top-feed), and bottom-
feed.
Water culture systems do not use media. Some popular water culture
systems are raft (also called floating and raceway), nutrient film technique
(NFT), and aeroponics.
Light
Think of a plant as a well-run factory that takes delivery of raw materials
and manufactures the most wondrous products. Just as a factory requires a
reliable energy source to turn the wheels of its machinery, plants need an
energy source in order to grow.
Artificial Light
Usually, natural sunlight is used for this important job. However, during the shorter
and darker days of winter, many growers use artificial lights to increase the
intensity of light (for photosynthesis) or to expand the daylight length. While the
sun radiates the full spectrum (wavelength or color of light) suitable for plant life,
different types of artificial lighting are selected for specific plant varieties and
optimum plant growth characteristics. Different groups of plants respond in
physically different ways to various wavelengths of radiation. Light plays an
extremely important role in the production of plant material. The lack of light is the
main inhibiting factor in plant growth. If you reduce the light by 10 percent, you
also reduce crop performance by 10 percent.
Light transmission should be your major consideration when purchasing a growing
structure for a protected crop. Glass is still the preferred material for covering
greenhouses because, unlike plastic films and sheeting, its light transmission ability
is indefinitely maintained.
No gardener can achieve good results without adequate light. If you intend to grow
indoors, avail yourself of some of the reading material that has been published on
this subject. If you are having trouble growing good plants, then light is the first
factor to question.
--Rob Smith
Natural Light
A large part of the success in growing hydroponically is planning where to place the
plants. Grow plants that have similar growing requirements in the same system.
Placing your system 1-2 feet away from a sunny window will give the best results
for most herbs and vegetables. Even your regular house lights help the plants to
grow. Make sure that all of the lights are out in your growing area during the night.
Plants need to rest a minimum of 4 hours every night. If your plants start to get
leggy (too tall and not very full), move the system to a spot that has more sun.
Once you find a good growing area, stick to it. Plants get used to their home
location. It may take some time to get used to a new place.
--Charles E. Musgrove
Macronutrients
Plants need around 16 mineral nutrients for optimal growth. However, not all these
nutrients are equally important for the plant. Three major minerals--nitrogen (N),
phosphorus (P), and potassium (K)--are used by plants in large amounts. These
three minerals are usually displayed as hyphenated numbers, like "15-30-15," on
commercial fertilizers. These numbers correspond to the relative percentage by
weight of each of the major nutrients--known as macronutrients--N, P, and K.
Macronutrients are present in large concentrations in plants. All nutrients combine in
numerous ways to help produce healthy plants. Usually, sulfur (S), calcium (Ca),
and magnesium (Mg) are also considered macronutrients.
These nutrients play many different roles in plants. Here are some of their dominant
functions:
Nitrogen (N)--promotes development of new leaves
Phosphorus (P)--aids in root growth and blooming
Potassium (K)--important for disease resistance and aids growth in extreme temperatures
Sulfur (S)--contributes to healthy, dark green color in leaves
Calcium (Ca)--promotes new root and shoot growth
Magnesium (Mg)--chlorophyll, the pigment that gives plants their green color and absorbs
sunlight to make food, contains a Mg ion
--Jessica Hankinson
Micronutrients
Boron (B), copper (Cu), cobalt (Co), iron (Fe) manganese (Mn), molybdenum (Mo),
and zinc (Zn) are only present in minute quantities in plants and are known as
micronutrients. Plants can usually acquire adequate amounts of these elements
from the soil, so most commercial fertilizers don't contain all of the micronutrients.
Hydroponic growers, however, don't have any soil to provide nutrients for their
plants. Therefore, nutrient solution that is marketed for hydroponic gardening
contain all the micronutrients.
--Jessica Hankinson
Nutrient Solution
In hydroponics, nutrient solution--sometimes just referred to as "nutrient"-is
used to feed plants instead of plain water. This is due to the fact that the
plants aren't grown in soil. Traditionally, plants acquire most of their
nutrition from the soil. When growing hydroponically, you need to add all of
the nutrients a plant needs to water. Distilled water works best for making
nutrient. Hydroponic supply stores have a variety of nutrient mixes for
specific crops and growth cycles. Always store solutions out of direct sunlight
to prevent any algae growth. See also conductivity,macronutrients,
and micronutrients.
Disposal Unlike regular water, you need to be careful where you dispose of
nutrient. Even organic nutrients and fertilizers can cause serious imbalances
in aquatic ecosystems. If you do not live near a stream, river, lake or other
water source, it is fine to use old nutrient on outdoor plants and lawn.
Another possibility is to use it on houseplants. However, if you live within
1,000 feet of a viable water source, do not use your spent nutrient in the
ground.
Osmosis
The ends of a plants roots arent open-ended like a drinking straw and they
definitely doesnt suck up a drink of water or nutrients (see capillary action).
Science is still seeking a complete understanding of osmosis, so to attempt a full
and satisfactory description of all thats involved in this process would be
impossible. However, we can understand the basic osmotic principle as it relates to
plants.
First, consider a piece of ordinary blotting paper, such as the commonly used filter
for home coffee machines. The paper might appear to be solid. However, if you
apply water to one side of it, youll soon see signs of the water appearing on the
opposite side. The walls of a feeding root act in much the same way. If you pour
water onto the top of the filter paper, gravity allows the water to eventually drip
through to the bottom side. Add the process of osmosis and water thats applied to
the bottom side drips through to the top.
With plants, this action allows water and nutrients to pass through the root walls
from the top, sides, and bottom. Osmosis is the natural energy force that moves
elemental ions through what appears to be solid material. A simplistic explanation
for how osmosis works, although not 100 percent accurate, is that the stronger ion
attracts the weaker through a semipermeable material. So, the elements within the
cells that make up plant roots attract water and nutrients through the root walls
when these compounds are stronger than the water and nutrients applied to the
outside of the roots.
It then follows that if you apply a strong nutrient to the plant roots--one thats
stronger than the compounds inside of the root--that the reverse action is likely to
occur! This process is called reverse osmosis. Many gardeners have at some time
committed the sin of killing their plants by applying too strong a fertilizer to their
plants, which causes reverse osmosis. Instead of feeding the plant, they have
actually been dragging the life force out of it.
Understanding how osmosis works, the successful grower can wisely use this
knowledge to promote maximum uptake of nutrients into the plants without causing
plant stress--or worse, plant death--from overfertilizing. All plants have a different
osmotic requirement or an optimum nutrient strength.
--Rob Smith
Oxygen
As a result of the process of photosynthesis, oxygen (O) is given off by
plants. Then, at night, when light isn't available for photosynthesis, this
process is reversed. At night, plants take in oxygen and consume the energy
they have stored during the day.
Pests and Diseases
Even though hydroponic gardeners dodge a large number of plant problems
by eschewing soil (which is a home to any number of plant enemies), pests
and diseases still manage to wreak havoc from time to
time. Botrytis, Cladosporium, Fusarium, and Verticillium cover most of the
genera of bacteria that can threaten your plants. The insects that can prove
annoying include aphids, caterpillars, cutworms, fungus gnats, leaf miners,
nematodes, spider mites, thrips, and whiteflies.
A few good ways to prevent infestation and infection are to:
Always maintain a sanitary growing environment
Grow naturally selected disease- and pest-resistant plant varieties
Keep your growing area properly ventilated and at the correct temperatures for your plants
Keep a close eye on your plants so if a problem does occur, you can act quickly
With insects, sometimes you can pick off and crush any large ones. Or you
can try to wash the infected plants with water or a mild soap solution (such
as Safer Soap).
If a problem gets out of control, it may be necessary to apply a biological
control in the form of a spray. Research which product will work best in your
situation. Always follow the instructions on pesticides very closely.
Alternatively, there are a number of control products on the market today
that feature a botanical compound or an ingredient that has been
synthesized from a plant material.
On botanical compounds as controlling agents:
Over the last few years, researchers from all around the world have started to take
a much closer look at any compounds present in the plant kingdom that might hold
the answer to our pest and disease control problems. Many companies have even
switched from producing synthetic pesticides to copying nature by synthesizing
naturally occurring compounds in a laboratory setting. Extracts of willow, cinnamon,
grapefruit, garlic, neem, bittersweet, lemon grass, derris, eucalyptus, and tomato
have been helpful in controlling diseases and pests.
--Dr. Lynette Morgan
pH
The pH of a nutrient solution is a measurement of its relative concentration of
positive hydrogen ions. Negative hydroxyl ions are produced by the way systems
filter and mix air into the nutrient solution feeding plants. Plants feed by an
exchange of ions. As ions are removed from the nutrient solution, pH rises.
Therefore, the more ions that are taken up by the plants, the greater the growth. A
solution with a pH value of 7.0 contains relatively equal concentrations of hydrogen
ions and hydroxyl ions. When the pH is below 7.0, there are more hydrogen ions
than hydroxyl ion. Such a solution "acidic." When the pH is above 7.0, there are
fewer hydrogen ions than hydroxyl ions. This means that the solution is "alkaline."
Test the pH level of your nutrient with a kit consisting of vials and liquid reagents.
These kits are available at local chemistry, hydroponic, nursery, garden supplier, or
swimming pool supply stores. It is also a good idea to test the pH level of
your water before adding any nutrients. If your solution is too alkaline add some
acid. Although such conditions rarely occur, sometimes you may have to reduce the
level of acidity by making the solution more alkaline. This can be achieved by
adding potassium hydroxide (or potash) to the solution in small amounts until it is
balanced once again.
--Charles E. Musgrove
Photosynthesis
Plants need to absorb many necessary nutrients from the nutrient
solution or--in the case of traditional agriculture--the soil. However, plants
can create some of their own food. Plants use the process of photosynthesis
to create food for energy. Carbohydrates are produced from carbon
dioxide (CO2) and a source of hydrogen (H)--such as water--in chlorophyll-
containing plant cells when they are exposed to light. This process results in
the production of oxygen (O).
Plant Problems
Every now and again, you are sure to run into a problem with your plants.
This is just a simple fact of any type of gardening. The key is to act quickly,
armed with quality knowledge.
Mineral Deficiency Symptoms
Nitrogen deficiency will cause yellowing of the leaves, especially in the older leaves.
The growth of new roots and shoots is stunted. In tomatoes, the stems may take on
a purple hue.
A phosphorous deficiency is usually associated with dark green foliage and stunted
growth. As in nitrogen deficiency, the stems may appear purple. But since the
leaves don't yellow as they do in nitrogen deficiency, the whole plant can take on a
purplish green color.
Iron deficiency results in yellowing between the leaf veins. In contrast to nitrogen
deficiency, the yellowing first appears in the younger leaves. After a prolonged
absence of iron, the leaves can turn completely white.
--Jessica Hankinson
Wilting
This condition can be caused by environmental factors or disease (usually
caused by Fusarium). Nutrient and media temperature can be adjusted to
remedy wilt. However, if Fusarium have taken hold, the chances that your
plants will survive are slim.
If wilting is due to environmental causes:
Try to spray the plants and roots with cool, clean water to rejuvenate them. If this
hasnt helped them by the next day, try it again. If the plants respond, top-off
the nutrient solution and check the pH. If the plants dont respond to the misting,
empty the tank, move it to a shadier spot, and refill with cool, fresh nutrient
solution. Dont reuse the old solution--start with fresh water and nutrients.
--Charles E. Musgrove
If wilting is due to a system blockage of nutrient:
I have seen tomato plants that have been so dehydrated due to a nutrient supply
blockage that they were lying flat and for all the world looked stone-cold dead.
When the nutrient flow resumed and the plants were given the less stressful
environment of nighttime, they rebounded so well that I wondered if I had dreamed
the previous days "disaster." The moral of this story is to always give plants a
chance to revive, even when the situation looks hopeless.
--Rob Smith
See also pests and diseases.
Propagation
Plants can be propagated by a number of methods. Growers can let a plant
go to seed, collect the seeds, and then start the cycle over again
(see germination). Another method is to take stem cuttings, which is also
known as cloning (because you are creating an exact copy of the parent
plant).
Although this process won't work with all plants, it is a highly effective
technique. Simply cut off a side shoot or the top of the main shoot just
below a growth node. Make sure that there are at least two growth nodes
above the cut. Remove any of the lower leaves near the base of the new
plant. This cutting can then be rooted by placing it in water or in a
propagation medium (perlite works well) that is kept moist. The use of some
rooting hormone can help your chances of success.
Pruning
Remove any discolored, insect-eaten, or otherwise sick-looking leaves from
plants. Picking off some outer leaves or cutting the top off a plant can help it
grow fuller. Use sharp scissors to prune your plants. Sometimes you will
want to prune a plant to focus its energy on the remaining shoots. Pruning is
an art and should be performed with care. Damaged or dying roots may also
need to be pruned from time to time.
Soil
Never use soil during any aspect of hydroponics. If you ever move a plant from a
soil-based situation to hydroponics, remove all traces of soil or potting mix from the
roots. Soil holds lots of microbes and other organisms and materials that love to
grow in and contaminate your hydroponic system. Some of these will actually
parasitize your plant and slow its growth. This is another advantage of hydroponic
growing: The plant can get on with growing without having to support a myriad of
other organisms as happens in conventional soil growing.
--Rob Smith
Temperature
Different plants have different germination and growing temperatures.
Always make sure that you check each plants growing requirements-especially
minimum and maximum temperature levels. Keep in mind that
specific varieties of plants may have different requirements.
Water
Because the water supply is the source of life for your plants, quality is important.
All plants rely on their ability to uptake water freely. Between 80 and 98 percent of
this uptake is required for transpiration (loosely compared to perspiration in
animals), which allows the plant to produce and somewhat control its immediate
microclimate. Plants also need clean, uncontaminated water to produce their own
healthy food supply.
--Rob Smith
The water you use in your hydroponic system needs to be pure. It is always
a good idea to test your water source before adding nutrients so you aren't
adding an element that is already present. In small systems, it would be
wise to use distilled water.
If you are starting a larger hydroponic operation, it would be a good idea to
have a water analysis completed. Factors such as sodium chloride (NaCl, or
salt) content and hardness will be of great use to growers. Also,
groundwater can have elements normally not present in conditioned water.
A key piece of advice: Get to know your water!
Emerald Hydroponics FAQ
What is Hydroponics?
Hydroponics is the method of growing plants using a soilless media which
could include a wide variety of examples like: gravel, peat, vermiculite
Perlite, old rubber tires, rockwool, and expanded clay aggregates. The
minerals that the plant needs are dissolved into the water which is then
watered directly to the plants. So, in short instead of the plants searching
throughout the soil for their minerals they draw them directly from the water
that they are being fed.
What is pH?
A measure of the acidity or alkalinity of a solution, numerically equal to 7
for neutral solutions, increasing with increasing alkalinity and decreasing
with increasing acidity. We recommend that you keep your solution at about
6.5 because that is the point at which the nutrients are the most soluble.
What is PPM?
PPM is very easily defined as Parts Per Million and can be used as the
measurement of a number of different things. More commonly in the
hydroponics world, this measurement is used to measure the amount of
Total Dissolved Solids in your nutrient solution or how much Co2 is in your
atmosphere.
What is the difference between High Pressure Sodium and Metal
Halide?
The difference between these two types of HID (High Intensity Discharge)
lights is the color spectrum that is emitted from each. The High Pressure
Sodium bulb emits light that is concentrated in the red to yellow side of the
spectrum and are weak in the blue-violet end. While the Metal Halide bulb
emits light that is very balanced and contains all the energy peaks at
wavelengths of the visible spectrum. Visually the Sodium bulbs will appear
very yellow-orange and the Halide bulbs will appear more blue-white in
color.
Should I use Sodium or Halide?
The Halide lights have a very balanced spectrum and are excellent for
vegetative growth or leafy plants like lettuce and basil. The Halide lights
produce between 65-115 lumens per watt which is a measure of the
efficiency of the bulb, or how much light you are producing for the amount
of electricity you are using. The Sodium lights produce light that is very
bright and concentrated on the yellow to red side of the color spectrum.
This color is not as balanced as the Halide but makes up for the lacking of a
balanced spectrum in the amount of light given off by the bulb. The Sodium
bulbs produce between 97 to 150 lumens per watt which is much higher
than the Halide bulbs. The Sodium bulbs are superior in life expectancy and
efficiency while the Halides a superior in spectral distribution so your
decision will be based on what is more important to you.
Why do people use Metal Halides for vegetative growth and High
Pressure Sodium's for flowering?
Many people switch between bulbs for different stages of growth for a
couple of reasons. First of all, Sodium bulbs have been known to make
some plants grow leggy and stretched out because of the yellow to red
spectrum that they give off. Metal Halides tend to keep these plants tighter
with less space between internodes. So some growers use the Metal Halide
lights during vegetative growth to keep the structural growth of the plant
nice and tight. But they switch to Sodium lights when the plants begin to
flower because the Sodium lights produce so much more light than the
Halides. Even though the Sodium's do not have as good a spectrum as the
Halides the intense light that is put off by the Sodium's aids in flower
development and fruit set. Do not be fooled though, you can use either
light throughout the life of a plant and get excellent results.
What size light should I purchase?
The first thing you need to do is figure out what kind of square footage
you are dealing with. Do not just figure for the whole room figure out what
the plant area is that you need to cover and multiply length x width to get
the square footage. Now, you will want to try and achieve at least 30 watts
per square foot. So if you have a 4 x 4 area which is 16 square feet and
you multiply by 30 watts, you get 480 watts. So for a 4 x 4 area you will
need to use at least a 430 watt light. Remember though that the amount of
light required will depend on the plants because some plants like lots of light
and some like low levels of light.
Do I need a ballast?
Yes. A ballast is required to start the lamp and to increase the voltage
required to run the lamp. The ballast is responsible for starting the lamps by
providing a high, fast charge of electricity. After the bulb lights, the range of
voltage and current are controlled by the transformer which is why the bulbs
operate so efficiently.
Are HID lights efficient?
Yes, very efficient compared to standard incandescent bulbs found in your
house. For example one 1000 watt sodium bulb produces as much light as
about 87 standard 100 watt incandescent bulbs.
Can I interchange bulbs between systems?
No. You should never interchange bulbs between systems unless they are
specifically made to do so. Lots of people ask if they can use a 250 watt
bulb in a 400 watt system and the answer is definitely not. You could put
yourself at risk by doing something like this because the bulb could become
unstable and explode. You should also never put Halide bulbs in a High
Pressure Sodium system because the ballast's are only meant to run the
type of bulb they are rated for and a Halide bulb in a Sodium system could
overheat and explode also. There are conversion bulbs manufactured that
are High Pressure Sodium bulbs that are meant to run off of a Halide
ballast. But once again only put the bulb in a system it is rated for.
Do these lights require any special wiring?
No. All systems are completely wired and just need to be plugged into
any grounded wall outlet. Custom voltages can be built into ballast's per
customer request (208v, 240v, 277v). Do not attempt to change the
voltage of the ballast unless you are an experienced electrician. Connecting
the wrong wires could result in a fried ballast or bulb, and even worse a fire.
What kind of plants can be grown using hydroponics?
Almost any type of plant can be grown using hydroponics some are just
more delicate than others. Usually if you can produce ideal environmental
conditions the hydroponic plants will be far superior to plants from the same
stock grown in soil.
How often should I change my nutrient solution?
There really isn't an amount of time that should be used to determine how
often you should change your solution. A good rule of thumb to follow first
of all is to top your reservoir off with fresh water without any nutrient
added. This is because you will lose water to evaporation and plant uptake
but the strength of the solution does not necessarily drop with the level of
the water. So, in some cases as the reservoir water level drops the solution
concentration actually goes up or gets stronger. So, add only fresh water
and then adjust your pH accordingly. Try and keep a record of how much
water you are putting in the reservoir to top it off and once the amount of
water added equals half of the reservoir capacity it is time to change the
solution and rinse the reservoir and growing medium. For example if you
have a 20 gallon reservoir and over the course of 12 days you have added
10 gallons of water, then it is time to change your solution.
Can I transfer plants from soil to hydroponics?
Yes, you can all you need to do is wash the roots of the plant by dipping
in water and try to remove as much of the soil matter as possible. Be very
careful with the delicate roots so the plant doesn't go into too much
transplant shock. After the roots are somewhat clean go ahead and pot the
plant in any of your favorite hydroponic media and begin a standard
watering regimen with a touch of B-1 in the solution for a week or so to aid
in the recovery from transplanting.
Do plants grown using hydroponics taste better than plants grown in
soil?
Quite often this is the case because the plants grown utilizing hydroponics
have all the essential nutrients readily available to the plant. In soil the
important micro nutrients are often locked away in the soil where the plants
cannot take full advantage of these minerals. That is why hydroponics is
superior because the grower has complete control over what minerals the
plants are feeding on and in what quantities. This advantage over soil often
produces produce that is far superior in taste, color, size, and nutritional
value.
How often do I need to water my plants?
Watering will all depend on the type of plants being grown, the size of
those plants, and what type of medium you are using. As you know plants
are very particular about being over or under-watered so this is an
important question. First you need to determine if the medium you are
using is absorbent or repellant. If you are using Rockwool you are dealing
with an absorbent medium while Hydroton is a good example of a repellent
medium that doesn't hold a lot of water. You want your medium to be moist
but not drenched and you want your medium to dry out somewhat between
waterings. So, if you watch your plants before and after waterings it will be
very easy to tell if you are watering too much or too little. If your plants wilt
before you water, but perk up immediately after watering, you may want to
water a little more often. If your plants wilt just after watering than you are
watering too much, and you should allot a little more time in between
waterings. A good general rule of thumb is to start plants being watered
about 2 to 3 times a day and increase as plants show signs of needing
water.
What Co2 system is right for me?
The deciding factor in this problem is almost always heat. Co2
generators burn either natural gas or propane to produce Co2. The
combustion of these fuels produces Co2 as a byproduct. Now the downfall of
the generators is the heat that is produced in the process. While the
generators are on they can raise temperatures in a grow room considerably.
The nice thing about generators is the availabilty of propane or natural gas
and the price of gas is considerably less than Co2. On the other hand, Co2
regulators are hooked up to Co2 tanks and regulate the amount of gas
being emitted through the use of a timer and a flowmeter. You set the
Cubic Feet per Hour (CFH) on the regulator and open the solenoid long
enough to charge the room with Co2 up to the desired PPM using the timer
to control the intervals. Co2 regulator type systems do not produce any
heat at all but are more expensive to maintain then the generator systems
since the price of Co2 is much higher than propane or natural gas.
What is the difference between Miracle-Gro and other commercially
available fertilizers and hydroponics nutrients?
Most of the fertilizers readily available are very general purpose mixes
that do not work well for all types of plants. The nutrients that we sell are
made specifically for plants grown in hydroponics systems that utilize sterile
growing mediums. Most commercially available fertilizers are meant for
fertilizing plants grown in soil and do not contain all the necessary trace
elements. Our fertilizers contain all those trace elements, and are also made
to be very soluble so that the plants can easily uptake the nutrients from the
watering solution. Those other fertilizers will work to grow plants but they
cannot compare to the results you will experience with our nutrients. Most
commercially available fertilizers are like junk food for your plants giving you
quick results that do not last very long.
What is the desired temperature range for the nutrient solution?
The optimal temperature of the nutrient solution should be in the range of
65 to 75 degrees Fahrenheit. Letting water stand uncovered in a container
overnight will help dissipate any chlorine in the water before you add it to
the reservoir.
How much electricity will I save running a grow light 240 volt?
There is no energy savings from running your lights at 240 volts. That is
a misconception that many people have. The main advantage is the fact
that you can run more lights on one electrical circuit. For example if you run
a 20 amp 120 volt circuit, you can only run two 1000 watt lights on that
circuit. If you were to wire the circuit up for 240 volts you can run four 1000
watt lights on that circuit. This makes for a lot less wiring but does not save
you on your electricity bill because each light still uses the same amount of
watts.
How can I tell if my seeds are viable?
This can be accomplished by presoaking your seeds. Fill a shot glass with
distilled water and place your seeds in it. After 24 hours the viable seeds
should have sank to the bottom. Those still floating are most likely not
viable and will not germinate.
Element Description of Deficiency and Toxicity
N Nitrogen: Deficiency: Plants will exhibit lack of vigor as older leaves
become yellow (chlorotic) from lack of chlorophyll. Chlorosis will
eventually spread throughout the plant. Stems, petioles and lower
leaf surfaces may turn purple.
Toxicity: Leaves are often dark green and in the early stages
abundant with foliage. If excess is severe, leaves will dry and
begin to fall off. Root system will remain under developed or
deteriorate after time. Fruit and flower set will be inhibited or
deformed.
P Phosphorus: Deficiency: Plants are stunted and older leaves often dark dull
green in color. Stems and leafstalk may turn purple. Plant
maturity is often delayed.
Toxicity: This condition is rare and usually buffered by pH
limitations. Excess phosphorus can interfere with the availability of
copper and zinc.
K Potassium: Deficiency: Older leaves are initially chlorotic but soon develop
dark necrotic lesions (dead tissue). First apparent on the tips and
margins of the leaves. Stem and branches may become weak and
easily broken.
Toxicity: Usually not absorbed excessively by plants. Excess
potassium can aggravate the uptake of magnesium, manganese,
zinc and iron.
S Sulfur: Deficiency: The initial symptoms are the yellowing of the entire
leaf including veins usually starting with the younger leaves. Leaf
tips may yellow and curl downward.
Toxicity: Leaf size will be reduced and overall growth will be
stunted. Leaves yellowing or scorched at edges.
Mg Magnesium: Deficiency: The older leaves will be the first to develop
interveinal chlorosis. Starting at leaf margin or tip and progressing
inward between the veins.
Toxicity: Magnesium toxicity are rare and not generally exhibited
visibly.
Ca Calcium: Deficiency: Young leaves are affected first and become small and
distorted or chlorotic with irregular margins, spotting or necrotic
areas. Bud development is inhibited and roots may be
underdeveloped or die back. Fruit may be stunted or deformed.
Toxicity: Difficult to distinguish visually. May precipitate with
sulfur in solution and cause clouding or residue in tank.
Fe Iron: Deficiency: Pronounced interveinal chlorosis similar to that cased
by magnesium deficiency but on the younger leaves.
Toxicity: Excess accumulation is rare but could cause bronzing or
tiny brown spots on leaf surface.
Mn Manganese: Deficiency: Interveinal chlorosis on younger or older leaves
followed by necrotic lesions or leaf shedding. Restricted growth
and failure to mature normally can also result.
Toxicity: Chlorosis, or blotchy leaf tissue due to insufficient
chlorophyll synthesis. Growth rate will slow and vigor will decline.
Cl Chlorine: Deficiency: Wilted chlorotic leaves become bronze in color. Roots
become stunted and thickened near tips.
Toxicity: Burning of leaf tip or margins. Bronzing, yellowing and
leaf splitting. Reduced leaf size and lower growth rate.
B Boron: Deficiency: Stem and root tips often die. Root tips often become
swollen and discolored. Internal tissues may rot and become host
to fungal disease. Leaves show various symptoms which include
drying, thickening, distorting, wilting, and chlorotic or necrotic
spotting.
Toxicity: Yellowing of leaf tip followed by necrosis of the leaves
beginning at tips or margins and progressing inward. Some plants
are especially sensitive to boron accumulation.
Zn Zinc: Deficiency: Chlorosis may accompany reduction of leaf size and a
shortening between internodes. Leaf margins are often distorted
or wrinkled.
Toxicity: Zinc in excess is extremely toxic and will cause rapid
death. Excess zinc interferes with iron causing chlorosis from iron
deficiency.
Cu Copper: Deficiency: Young leaves often become dark green and twisted.
They may die back or just exhibit necrotic spots. Growth and yield
will be deficient as well.
Toxicity: Reduced growth followed by symptoms of iron chlorosis,
stunting, reduced branching, abnormal darkening and thickening of
roots. This element is essential but extremely toxic in excess.
Mo Molybdenum
eficiency: Often interveinal chlorosis which occurs first on older leaves, then progressing to the entire plant. Developing severely
twisted younger leaves which eventually die.
Toxicity: Excess may cause discoloration of leaves depending on
plant species. This condition is rare but could occur from
accumulation by continuous application. Used by the plant in very
small quantities.
Ca Calcium: Deficiency: Young leaves are affected first and become small and
distorted or chlorotic with irregular margins, spotting or necrotic
areas. Bud development is inhibited and roots may be
underdeveloped or die back. Fruit may be stunted or deformed.
Toxicity: Difficult to distinguish visually. May precipitate with
sulfur in solution and cause clouding or residue in tank.
Fe Iron: Deficiency: Pronounced interveinal chlorosis similar to that cased
by magnesium deficiency but on the younger leaves.
Toxicity: Excess accumulation is rare but could cause bronzing or
tiny brown spots on leaf surface.
Mn Manganese: Deficiency: Interveinal chlorosis on younger or older leaves
followed by necrotic lesions or leaf shedding. Restricted growth
and failure to mature normally can also result.
Toxicity: Chlorosis, or blotchy leaf tissue due to insufficient
chlorophyll synthesis. Growth rate will slow and vigor will decline.
Cl Chlorine: Deficiency: Wilted chlorotic leaves become bronze in color. Roots
become stunted and thickened near tips.
Toxicity: Burning of leaf tip or margins. Bronzing, yellowing and
leaf splitting. Reduced leaf size and lower growth rate.
B Boron: Deficiency: Stem and root tips often die. Root tips often become
swollen and discolored. Internal tissues may rot and become host
to fungal disease. Leaves show various symptoms which include
drying, thickening, distorting, wilting, and chlorotic or necrotic
spotting.
Toxicity: Yellowing of leaf tip followed by necrosis of the leaves
beginning at tips or margins and progressing inward. Some plants
are especially sensitive to boron accumulation.
Zn Zinc: Deficiency: Chlorosis may accompany reduction of leaf size and a
shortening between internodes. Leaf margins are often distorted
or wrinkled.
Toxicity: Zinc in excess is extremely toxic and will cause rapid
death. Excess zinc interferes with iron causing chlorosis from iron
deficiency.
Cu Copper: Deficiency: Young leaves often become dark green and twisted.
They may die back or just exhibit necrotic spots. Growth and yield
will be deficient as well.
Toxicity: Reduced growth followed by symptoms of iron chlorosis,
stunting, reduced branching, abnormal darkening and thickening of
roots. This element is essential but extremely toxic in excess.
Mo Molybdenum
eficiency: Often interveinal chlorosis which occurs first on older leaves, then progressing to the entire plant. Developing severely
twisted younger leaves which eventually die.
Toxicity: Excess may cause discoloration of leaves depending on
plant species. This condition is rare but could occur from
accumulation by continuous application. Used by the plant in very
small quantities.
This page has been designed to help answer the important questions
beginning growers might have when just getting started in hydroponics. A
lot of these concepts are connected to each other. Follow the links and put
the pieces of this growing puzzle together.
The more you know, the easier it is to grow!
Carbon Dioxide
During photosynthesis, plants use carbon dioxide (CO2), light, and hydrogen
(usually water) to produce carbohydrates, which is a source of
food. Oxygen is given off in this process as a by-product. Light is a key
variable in photosynthesis.
Conductivity
Measuring nutrient solution strength is a relatively simple process. However, the
electronic devices manufactured to achieve this task are quite sophisticated and use
the latest microprocessor technology. To understand how these devices work, you
have to know that pure water doesnt conduct electricity. But as salts are dissolved
into the pure water, electricity begins to be conducted. An electrical current will
begin to flow when live electrodes are placed into the solution. The more salts that
are dissolved, the stronger the salt solution and, correspondingly, the more
electrical current that will flow. This current flow is connected to special electronic
circuitry that allows the grower to determine the resultant strength of the nutrient
solution.
The scale used to measure nutrient strength is electrical conductivity (EC) or
conductivity factor (CF). The CF scale is most commonly used in hydroponics. It
spans from 0 to more than 100 CF units. The part of the scale generally used by
home hydroponic gardeners spans 0-100 CF units. The part of the scale generally
used by commercial or large-scale hydroponic growers is from 2 to 4 CF. (strength
for growing watercress and some fancy lettuce) to as high as approximately 35 CF
for fruits, berries, and ornamental trees. Higher CF values are used by experienced
commercial growers to obtain special plant responses and for many of the modern
hybrid crops, such as tomatoes and some peppers. Most other plant types fall
between these two figures and the majority is grown at 13-25 CF.
--Rob Smith
Germination
When a seed first begins to grow, it is germinating. Seeds are germinated in
a growing medium, such as perlite. Several factors are involved in this
process. First, the seed must be active--and alive--and not in dormancy.
Most seeds have a specific temperature range that must be achieved.
Moisture and oxygen must be present. And, for some seeds, specified levels
of light or darkness must be met. Check the specifications of seeds to see
their germination requirements.
The first two leaves that sprout from a seed are called the seed leaves, or
cotyledons. These are not the true leaves of a plant. The seed develops
these first leaves to serve as a starting food source for the young,
developing plant.
Growing Medium
Soil is never used in hydroponic growing. Some systems have the ability to
support the growing plants, allowing the bare roots to have maximum
exposure to the nutrient solution. In other systems, the roots are supported
by a growing medium. Some types of media also aid in moisture and
nutrient retention. Different media are better suited to specific plants and
systems. It is best to research all of your options and to get some
recommendations for systems and media before making investing in or
building an operation. Popular growing media include:
Composted bark. It is usually organic and can be used for seed germination.
Expanded clay. Pellets are baked in a very hot oven, which causes them to expand, creating a porous end
product.
Gravel. Any type can be used. However, gravel can add minerals to nutrient. Always make sure it is
clean.
Oasis. This artificial, foam-based material is commonly known from its use as an arrangement base in the
floral industry.
Peat moss. This medium is carbonized and compressed vegetable matter that has been partially
decomposed.
Perlite. Volcanic glass is mined from lava flows and heated in furnaces to a high temperature, causing the
small amount of moisture inside to expand. This converts the hard glass into small, sponge-like kernels.
Pumice. This is a glassy material that is formed by volcanic activity. Pumice is lightweight due to its large
number of cavities produced by the expulsion of water vapor at a high temperature as lava surfaces.
Rockwool. This is created by melting rock at a high temperature and then spinning it into fibers.
Sand. This medium varies in composition and is usually used in conjunction with another medium.
Vermiculite. Similar to perlite except that it has a relatively high cation exchange capacity--meaning it
can hold nutrients for later use.
There are a number of other materials that can (and are) used as growing
media. Hydroponic gardeners tend to be an innovative and experimental
group.
Hydroponic Systems
The apparatuses used in hydroponic growing are many and varied. There are
two basic divisions between systems: media-based and water culture. Also,
systems can be either active or passive. Active systems use pumps and
usually timers and other electronic gadgets to run and monitor the
operation. Passive systems may also incorporate any number of gadgets.
However, they to not use pumps and may rely on the use of a wicking agent
to draw nutrient to the roots.
Media-based systems--as their name implies--use some form of growing
medium. Some popular media-based systems include ebb-and-flow (also
called flood-and-drain), run-to-waste, drip-feed (or top-feed), and bottom-
feed.
Water culture systems do not use media. Some popular water culture
systems are raft (also called floating and raceway), nutrient film technique
(NFT), and aeroponics.
Light
Think of a plant as a well-run factory that takes delivery of raw materials
and manufactures the most wondrous products. Just as a factory requires a
reliable energy source to turn the wheels of its machinery, plants need an
energy source in order to grow.
Artificial Light
Usually, natural sunlight is used for this important job. However, during the shorter
and darker days of winter, many growers use artificial lights to increase the
intensity of light (for photosynthesis) or to expand the daylight length. While the
sun radiates the full spectrum (wavelength or color of light) suitable for plant life,
different types of artificial lighting are selected for specific plant varieties and
optimum plant growth characteristics. Different groups of plants respond in
physically different ways to various wavelengths of radiation. Light plays an
extremely important role in the production of plant material. The lack of light is the
main inhibiting factor in plant growth. If you reduce the light by 10 percent, you
also reduce crop performance by 10 percent.
Light transmission should be your major consideration when purchasing a growing
structure for a protected crop. Glass is still the preferred material for covering
greenhouses because, unlike plastic films and sheeting, its light transmission ability
is indefinitely maintained.
No gardener can achieve good results without adequate light. If you intend to grow
indoors, avail yourself of some of the reading material that has been published on
this subject. If you are having trouble growing good plants, then light is the first
factor to question.
--Rob Smith
Natural Light
A large part of the success in growing hydroponically is planning where to place the
plants. Grow plants that have similar growing requirements in the same system.
Placing your system 1-2 feet away from a sunny window will give the best results
for most herbs and vegetables. Even your regular house lights help the plants to
grow. Make sure that all of the lights are out in your growing area during the night.
Plants need to rest a minimum of 4 hours every night. If your plants start to get
leggy (too tall and not very full), move the system to a spot that has more sun.
Once you find a good growing area, stick to it. Plants get used to their home
location. It may take some time to get used to a new place.
--Charles E. Musgrove
Macronutrients
Plants need around 16 mineral nutrients for optimal growth. However, not all these
nutrients are equally important for the plant. Three major minerals--nitrogen (N),
phosphorus (P), and potassium (K)--are used by plants in large amounts. These
three minerals are usually displayed as hyphenated numbers, like "15-30-15," on
commercial fertilizers. These numbers correspond to the relative percentage by
weight of each of the major nutrients--known as macronutrients--N, P, and K.
Macronutrients are present in large concentrations in plants. All nutrients combine in
numerous ways to help produce healthy plants. Usually, sulfur (S), calcium (Ca),
and magnesium (Mg) are also considered macronutrients.
These nutrients play many different roles in plants. Here are some of their dominant
functions:
Nitrogen (N)--promotes development of new leaves
Phosphorus (P)--aids in root growth and blooming
Potassium (K)--important for disease resistance and aids growth in extreme temperatures
Sulfur (S)--contributes to healthy, dark green color in leaves
Calcium (Ca)--promotes new root and shoot growth
Magnesium (Mg)--chlorophyll, the pigment that gives plants their green color and absorbs
sunlight to make food, contains a Mg ion
--Jessica Hankinson
Micronutrients
Boron (B), copper (Cu), cobalt (Co), iron (Fe) manganese (Mn), molybdenum (Mo),
and zinc (Zn) are only present in minute quantities in plants and are known as
micronutrients. Plants can usually acquire adequate amounts of these elements
from the soil, so most commercial fertilizers don't contain all of the micronutrients.
Hydroponic growers, however, don't have any soil to provide nutrients for their
plants. Therefore, nutrient solution that is marketed for hydroponic gardening
contain all the micronutrients.
--Jessica Hankinson
Nutrient Solution
In hydroponics, nutrient solution--sometimes just referred to as "nutrient"-is
used to feed plants instead of plain water. This is due to the fact that the
plants aren't grown in soil. Traditionally, plants acquire most of their
nutrition from the soil. When growing hydroponically, you need to add all of
the nutrients a plant needs to water. Distilled water works best for making
nutrient. Hydroponic supply stores have a variety of nutrient mixes for
specific crops and growth cycles. Always store solutions out of direct sunlight
to prevent any algae growth. See also conductivity,macronutrients,
and micronutrients.
Disposal Unlike regular water, you need to be careful where you dispose of
nutrient. Even organic nutrients and fertilizers can cause serious imbalances
in aquatic ecosystems. If you do not live near a stream, river, lake or other
water source, it is fine to use old nutrient on outdoor plants and lawn.
Another possibility is to use it on houseplants. However, if you live within
1,000 feet of a viable water source, do not use your spent nutrient in the
ground.
Osmosis
The ends of a plants roots arent open-ended like a drinking straw and they
definitely doesnt suck up a drink of water or nutrients (see capillary action).
Science is still seeking a complete understanding of osmosis, so to attempt a full
and satisfactory description of all thats involved in this process would be
impossible. However, we can understand the basic osmotic principle as it relates to
plants.
First, consider a piece of ordinary blotting paper, such as the commonly used filter
for home coffee machines. The paper might appear to be solid. However, if you
apply water to one side of it, youll soon see signs of the water appearing on the
opposite side. The walls of a feeding root act in much the same way. If you pour
water onto the top of the filter paper, gravity allows the water to eventually drip
through to the bottom side. Add the process of osmosis and water thats applied to
the bottom side drips through to the top.
With plants, this action allows water and nutrients to pass through the root walls
from the top, sides, and bottom. Osmosis is the natural energy force that moves
elemental ions through what appears to be solid material. A simplistic explanation
for how osmosis works, although not 100 percent accurate, is that the stronger ion
attracts the weaker through a semipermeable material. So, the elements within the
cells that make up plant roots attract water and nutrients through the root walls
when these compounds are stronger than the water and nutrients applied to the
outside of the roots.
It then follows that if you apply a strong nutrient to the plant roots--one thats
stronger than the compounds inside of the root--that the reverse action is likely to
occur! This process is called reverse osmosis. Many gardeners have at some time
committed the sin of killing their plants by applying too strong a fertilizer to their
plants, which causes reverse osmosis. Instead of feeding the plant, they have
actually been dragging the life force out of it.
Understanding how osmosis works, the successful grower can wisely use this
knowledge to promote maximum uptake of nutrients into the plants without causing
plant stress--or worse, plant death--from overfertilizing. All plants have a different
osmotic requirement or an optimum nutrient strength.
--Rob Smith
Oxygen
As a result of the process of photosynthesis, oxygen (O) is given off by
plants. Then, at night, when light isn't available for photosynthesis, this
process is reversed. At night, plants take in oxygen and consume the energy
they have stored during the day.
Pests and Diseases
Even though hydroponic gardeners dodge a large number of plant problems
by eschewing soil (which is a home to any number of plant enemies), pests
and diseases still manage to wreak havoc from time to
time. Botrytis, Cladosporium, Fusarium, and Verticillium cover most of the
genera of bacteria that can threaten your plants. The insects that can prove
annoying include aphids, caterpillars, cutworms, fungus gnats, leaf miners,
nematodes, spider mites, thrips, and whiteflies.
A few good ways to prevent infestation and infection are to:
Always maintain a sanitary growing environment
Grow naturally selected disease- and pest-resistant plant varieties
Keep your growing area properly ventilated and at the correct temperatures for your plants
Keep a close eye on your plants so if a problem does occur, you can act quickly
With insects, sometimes you can pick off and crush any large ones. Or you
can try to wash the infected plants with water or a mild soap solution (such
as Safer Soap).
If a problem gets out of control, it may be necessary to apply a biological
control in the form of a spray. Research which product will work best in your
situation. Always follow the instructions on pesticides very closely.
Alternatively, there are a number of control products on the market today
that feature a botanical compound or an ingredient that has been
synthesized from a plant material.
On botanical compounds as controlling agents:
Over the last few years, researchers from all around the world have started to take
a much closer look at any compounds present in the plant kingdom that might hold
the answer to our pest and disease control problems. Many companies have even
switched from producing synthetic pesticides to copying nature by synthesizing
naturally occurring compounds in a laboratory setting. Extracts of willow, cinnamon,
grapefruit, garlic, neem, bittersweet, lemon grass, derris, eucalyptus, and tomato
have been helpful in controlling diseases and pests.
--Dr. Lynette Morgan
pH
The pH of a nutrient solution is a measurement of its relative concentration of
positive hydrogen ions. Negative hydroxyl ions are produced by the way systems
filter and mix air into the nutrient solution feeding plants. Plants feed by an
exchange of ions. As ions are removed from the nutrient solution, pH rises.
Therefore, the more ions that are taken up by the plants, the greater the growth. A
solution with a pH value of 7.0 contains relatively equal concentrations of hydrogen
ions and hydroxyl ions. When the pH is below 7.0, there are more hydrogen ions
than hydroxyl ion. Such a solution "acidic." When the pH is above 7.0, there are
fewer hydrogen ions than hydroxyl ions. This means that the solution is "alkaline."
Test the pH level of your nutrient with a kit consisting of vials and liquid reagents.
These kits are available at local chemistry, hydroponic, nursery, garden supplier, or
swimming pool supply stores. It is also a good idea to test the pH level of
your water before adding any nutrients. If your solution is too alkaline add some
acid. Although such conditions rarely occur, sometimes you may have to reduce the
level of acidity by making the solution more alkaline. This can be achieved by
adding potassium hydroxide (or potash) to the solution in small amounts until it is
balanced once again.
--Charles E. Musgrove
Photosynthesis
Plants need to absorb many necessary nutrients from the nutrient
solution or--in the case of traditional agriculture--the soil. However, plants
can create some of their own food. Plants use the process of photosynthesis
to create food for energy. Carbohydrates are produced from carbon
dioxide (CO2) and a source of hydrogen (H)--such as water--in chlorophyll-
containing plant cells when they are exposed to light. This process results in
the production of oxygen (O).
Plant Problems
Every now and again, you are sure to run into a problem with your plants.
This is just a simple fact of any type of gardening. The key is to act quickly,
armed with quality knowledge.
Mineral Deficiency Symptoms
Nitrogen deficiency will cause yellowing of the leaves, especially in the older leaves.
The growth of new roots and shoots is stunted. In tomatoes, the stems may take on
a purple hue.
A phosphorous deficiency is usually associated with dark green foliage and stunted
growth. As in nitrogen deficiency, the stems may appear purple. But since the
leaves don't yellow as they do in nitrogen deficiency, the whole plant can take on a
purplish green color.
Iron deficiency results in yellowing between the leaf veins. In contrast to nitrogen
deficiency, the yellowing first appears in the younger leaves. After a prolonged
absence of iron, the leaves can turn completely white.
--Jessica Hankinson
Wilting
This condition can be caused by environmental factors or disease (usually
caused by Fusarium). Nutrient and media temperature can be adjusted to
remedy wilt. However, if Fusarium have taken hold, the chances that your
plants will survive are slim.
If wilting is due to environmental causes:
Try to spray the plants and roots with cool, clean water to rejuvenate them. If this
hasnt helped them by the next day, try it again. If the plants respond, top-off
the nutrient solution and check the pH. If the plants dont respond to the misting,
empty the tank, move it to a shadier spot, and refill with cool, fresh nutrient
solution. Dont reuse the old solution--start with fresh water and nutrients.
--Charles E. Musgrove
If wilting is due to a system blockage of nutrient:
I have seen tomato plants that have been so dehydrated due to a nutrient supply
blockage that they were lying flat and for all the world looked stone-cold dead.
When the nutrient flow resumed and the plants were given the less stressful
environment of nighttime, they rebounded so well that I wondered if I had dreamed
the previous days "disaster." The moral of this story is to always give plants a
chance to revive, even when the situation looks hopeless.
--Rob Smith
See also pests and diseases.
Propagation
Plants can be propagated by a number of methods. Growers can let a plant
go to seed, collect the seeds, and then start the cycle over again
(see germination). Another method is to take stem cuttings, which is also
known as cloning (because you are creating an exact copy of the parent
plant).
Although this process won't work with all plants, it is a highly effective
technique. Simply cut off a side shoot or the top of the main shoot just
below a growth node. Make sure that there are at least two growth nodes
above the cut. Remove any of the lower leaves near the base of the new
plant. This cutting can then be rooted by placing it in water or in a
propagation medium (perlite works well) that is kept moist. The use of some
rooting hormone can help your chances of success.
Pruning
Remove any discolored, insect-eaten, or otherwise sick-looking leaves from
plants. Picking off some outer leaves or cutting the top off a plant can help it
grow fuller. Use sharp scissors to prune your plants. Sometimes you will
want to prune a plant to focus its energy on the remaining shoots. Pruning is
an art and should be performed with care. Damaged or dying roots may also
need to be pruned from time to time.
Soil
Never use soil during any aspect of hydroponics. If you ever move a plant from a
soil-based situation to hydroponics, remove all traces of soil or potting mix from the
roots. Soil holds lots of microbes and other organisms and materials that love to
grow in and contaminate your hydroponic system. Some of these will actually
parasitize your plant and slow its growth. This is another advantage of hydroponic
growing: The plant can get on with growing without having to support a myriad of
other organisms as happens in conventional soil growing.
--Rob Smith
Temperature
Different plants have different germination and growing temperatures.
Always make sure that you check each plants growing requirements-especially
minimum and maximum temperature levels. Keep in mind that
specific varieties of plants may have different requirements.
Water
Because the water supply is the source of life for your plants, quality is important.
All plants rely on their ability to uptake water freely. Between 80 and 98 percent of
this uptake is required for transpiration (loosely compared to perspiration in
animals), which allows the plant to produce and somewhat control its immediate
microclimate. Plants also need clean, uncontaminated water to produce their own
healthy food supply.
--Rob Smith
The water you use in your hydroponic system needs to be pure. It is always
a good idea to test your water source before adding nutrients so you aren't
adding an element that is already present. In small systems, it would be
wise to use distilled water.
If you are starting a larger hydroponic operation, it would be a good idea to
have a water analysis completed. Factors such as sodium chloride (NaCl, or
salt) content and hardness will be of great use to growers. Also,
groundwater can have elements normally not present in conditioned water.
A key piece of advice: Get to know your water!
