A thread on cannabis nutrient deficiencies

Discussion in 'Indoor Growing' started by billy4479, Sep 8, 2011.


    billy4479 Moderator


    billy4479 Moderator


    Although it is perhaps one of the most overlooked aspects, pH is very important in hydroponic and organic as well as regular soil gardening. pH is measured on a scale of 1-14 with 7 being neutral. Acids are lower than 7 and alkalis (bases) are above 7.
    This article deals with the pH of hydroponic gardening and the availability of nutrients at different pH levels in a soilless growing medium. Organic and soil gardening have different levels, so the following chart doesn't pertain to them.
    To be technical, the term pH refers to the potential hydrogen-hydroxyl ion content of a solution. Solutions ionize into positive and negative ions. If the solution has more hydrogen (positive) ions than hydroxyl (negative) ions then it is an acid (1-6.9 on the pH scale). Conversely if the solution has more hydroxyl ions than hydrogen it is alkaline (or base), with a range of 7.1-14 on the pH scale.
    Pure water has a balance of hydrogen (H+) and hydroxyl (OH-) ions and is therefore pH neutral (pH 7). When the water is less than pure it can have a pH either higher or lower than 7.
    The pH scale is logarithmic, which means that each unit of change equals a tenfold change in the hydrogen/hydroxyl ion concentration. To put it another way, a solution with a pH of 6.0 is 10 times more acidic than a solution with a value of pH 7.0, and a solution with a pH value of 5.0 would be 10 times more acidic than the solution of 6.0 pH and 100 times more acidic than the solution with a 7.0 pH. This means that when you are adjusting the pH of your nutrient solution and you need to move it 2 points (example: 7.5 to 5.5) you would have to use 10 times more adjuster than if you were moving the pH value just 1 point (7.5 to 6.5).


    When the pH is not at the proper level the plant will lose its ability to absorb some of the essential elements required for healthy growth. For all plants there is a particular pH level that will produce optimum results (see chart 1 below). This pH level will vary from plant to plant, but in general most plants prefer a slightly acid growing environment (between 5.5-6.0), although most plants can still survive in an environment with a pH of between 5.0 and 7.5.
    When pH rises above 6.5 some of the nutrients and micro-nutrients begin to precipitate out of solution and can stick to the walls of the reservoir and growing chambers. For example: Iron will be about half precipitated at the pH level of 7.3 and at about 8.0 there is virtually no iron left in solution at all. In order for your plants to use the nutrients they must be dissolved in the solution. Once the nutrients have precipitated out of solution your plants can no longer absorb them and will suffer deficiency and death if left uncorrected. Some nutrients will precipitate out of solution when the pH drops also. Chart 2 (below) will give you an idea of what happens to availability some of the nutrients at different pH levels:
    Chart 2pH Values For Different
    Hydroponic Crops
    Availability Of Nutrients
    Available At Different
    pH Levels(From Hydroponic Food Production
    by Howard M. Resh

    Woodbridge Press, 1987)

    This chart is for soiless (hydroponic) gardening only and
    does not apply to organic or dirt gardening.
    PlantpH RangeBeans

    When you are growing hydroponically checking and adjusting pH is a simple matter. It can be a bit more complicated when growing organically or in soil. There are several ways to check the pH of the nutrient solution in your hydroponic system.
    Paper test strips are probably the most inexpensive way to check the pH of the nutrient solution. These paper strips are impregnated with a pH sensitive dye which changes color when dipped into the nutrient solution. The paper strip is then compared to a color chart to determine the pH level of the solution being checked. These test strips are inexpensive, but they can be hard to read, because the colors differences are subtle.
    Liquid pH test kits are probably the most popular method to check pH for the hobby gardener. These liquid test kits work by adding a few drops of a pH sensitive dye to a small amount of the nutrient solution and then comparing the color of the resulting liquid with a color chart. While slightly more expensive than the paper test strips, they are easier to read and extremely accurate and reliable.
    The Most high-tech way to check pH is to use the digital meters. These meters come in a huge array of sizes and prices. The most popular type of pH meter for the hobby gardener is the digital pen. These pens are manufactured by several different companies and are very handy and easy to use. You simply dip the electrode into the nutrient solution for a few moments and the pH value is displayed on an LCD screen.
    The pH meters are very accurate (when properly calibrated) and fast. They need to cared for properly however, or they will quit working. The glass bulb electrode must be kept clean and some are required to be wet at all times. The pH meters are actually very sensitive volt meters and are susceptible to problems with the electrode.
    The pH meters are slightly temperature sensitive. Many of the pH meters on the market have Automatic Temperature Compensation (ATC), which corrects the reading with respect to temperature. On meters without ATC the pH should be checked at the same time of day each time in order to minimize any temperature related fluctuations.
    The pH meters usually need to be calibrated frequently, as the meters can drift and to insure accuracy you must check calibration often. With most pens, the tip needs to be stored in an electrode storage solution or in a buffer solution and should never be allowed to dry out.
    Due to the fact that pH meters have a reputation of breaking down without warning it is a good idea to keep an emergency backup for checking pH (paper test strips or a liquid pH test kit), just in case.


    There are several chemicals used by the hobby gardener to adjust pH. The most popular are phosphoric acid (to lower pH) and potassium hydroxide (to raise pH). Both of these chemicals are relatively safe, although they can cause burns and should never come in contact with the eyes. Most hydroponic supply stores sell pH adjusters that are diluted to a level that is reasonably safe and easy to use. Concentrated adjusters can cause large pH changes and can make adjusting the pH very frustrating.
    Several other chemicals can be used to adjust the pH of hydroponic nutrient solutions. Nitric acid and sulfuric acid can be used to lower pH but are much more dangerous than phosphoric acid. Food grade citric acid is sometimes used in organic gardening to lower pH.
    Always add the nutrients to the water before checking and adjusting the pH of your solution. The fertilizer will usually lower the pH of the water due to its chemical makeup. After adding nutrient and mixing the solution, check the pH using whatever method you chose. If the pH needs to be adjusted, add the appropriate adjuster. Use small amounts of pH adjuster until you get familiar with the process. Recheck the pH and repeat the above steps until the pH level is where you want it to be. Once you have done this a few times, you'll nail it the first try. Beyond all the facts and figures, this critical step is truly simple and easy.
    The pH of the nutrient solution will have a tendency to go up as the plants use the nutrients. As a result the pH needs to be checked periodically and adjusted if necessary. To start out, I suggest that you check pH on a daily basis. Each system will change pH at a different rate depending on a variety of factors. The type of growing medium used, the weather, the kind of plants and even the age of the plants all effect the pH variations.

    billy4479 Moderator

    Hydroponic cultivation is considered by many to be the superior method of agriculture both on a commercial level and for personal crop production. Plants are fed their exact nutritional requirements, provided with controlled environmental surroundings and supplied with their precise lighting needs. Nature could not offer better growing conditions!
    The incredible part about hydroponics is.it's easy! Or at least it should be. Over the past decade the insurgence of pseudo-scientific information in the hydroponic industry has become dazzling. There are additives, boosters and supplements for your nutrition regime. New liquid tonics or powdered concoctions pop up daily with a promise to increase nutrient uptake, keep roots strong and healthy, accelerate growth and increase flower size and fruit flavour. There are detoxifiers and leaching solutions and an abundance of other additives that your plants can't do without. or so the savvy marketing people would have you believe!
    The web offers a wealth of ideas on hydroponic growing, each site offering information skewed to the particular products sold by the owner of that domain. Wading through the labyrinth of information can be mind boggling.
    As with anything the consumer must also be savvy and educate themselves about the different products available. Understanding what a plant actually needs to sustain life is crucial to help sort through the rhetoric.
    To understand what growth influencing factors (GIF's) are to a plant is to understand basic plant physiology. Any one of these GIF's plays a big part in continuance of a plant's life: Light, potential hydrogen (pH), carbon dioxide (CO2), oxygen (O2), temperature, humidity and nutrition.
    Light requirements can be met with natural sunshine or with an artificial light source. (CO2), (O2), temperature and humidity can all be controlled by the grower. Plants will survive in the same comfort environment as humans so it is not difficult to supply an adequate amount of these GIF's. However, supplementation or tighter controls of these GIF's may optimize growing conditions.
    pH is the level of acid or alkalinity of your nutrient, pH 7 being neutral. The pH level of your nutrition solution determines the plant's ability to use the food efficiently. pH is easily maintained at the proper level by a simple litmus paper test and then adjusting as necessary.
    In hydroponics plants absorb nutrients through their tiny root hairs. The roots will only take up as much nutrition as they require. It is impossible to overfeed in a hydroponic system, however, mixing a solution too high in nutrient levels will result in root dehydration.
    All plants require a balance of nitrogen, phosphorous and potassium (N-P-K) and trace elements to grow properly. The other GIF's influence a plants' ability of utilize these nutrients adequately.
    There are 20 macro and micro-nutrients required for plant growth:
    Macronutrients are required in large amounts
    Component of all organic compounds
    Supplied by air & water
    Combines with oxygen to form water
    Part of chlorophyll, amino acids, proteins
    Used in photosynthesis and almost all aspects of growth
    Activates enzymes, used in formation of sugar and starch
    Used in cell growth and division, part of cell wall
    Part of chlorophyll, activates enzymes
    Part of amino acids and proteins

    Micronutrients are required in trace amounts
    Affects reproduction
    Aids in root growth
    Used in chlorophyll, activates enzymes
    Used in Photosynthesis
    Part of chlorophyll, activates enzymes
    Used for water movement
    Part of enzymes, used in auxins
    Used in nitrogen fixation
    Liberates Nitrogen
    Fixates Nitrogen
    Makes tougher cell walls:
    enhances heat and drought tolerance

    Small amounts of these nutrients can be assimilated through healthy soil, however they are quickly depleted rendering the soil void of all life sustaing properties.
    In hydroponic cultivation essential nutrients are provided in ideal proportions. The inert growing medium does not contain any nutrients. Through extensive research conducted in the 1920's (and much trial and error) scientists were able to determine a very specific blend of mineral salts that when mixed with water would completely nourish plants. Immersing plant's roots directly in this solution proved to be very fruitful and lauched the way for modern hydroponic practices. The refinement of this technique of cultivation has been on-going ever since.
    The word hydroponics was derived from the Greek word 'Hydro' meaning water and 'Ponos' meaning working, literal translation, water-working. Today's definition of hydroponics is 'soilles cultivation' which means simply, growing without soil.
    The simplicity of hydroponics has been vastly understated. It is easy to grow almost anything hydroponically. Our North American society insists on complicating things. Sure there is a benefit to using some of the additives and supplements available to enhance crop production. But, if you are just starting out it may be wise to keep things as basic as possible. Hydroponic windowsill gardens are available and ideal for planting low light plants. Fresh herbs can be grown in a kitchen window ready for use in any recipe. A small 4' x 4' garden can be easily maintained and will yield a profusion of crops.
    Nutrition is an intregal part of good crop health and a successful yield. Start off very basic using a high quality concentrate nutrient. Any reputable hydroponic shop will be able to advise you on which product to choose. Most nutrient formulas are 2 or 3 part. This is because these fertilizers contain mineral salts which, when mixed together in a concentrated form will bind together causing them to fall out of suspension. Follow the manufactures instructions carefully and only mix each part into the water.
    Hydroponic formulations are structured for the different stages of growth. A plant's nutritional requirements shift from their vegetative stage to their flowering stage therefore, there is a grow formula and a bloom formula.
    Plants need higher levels of nitrogen during their vegetative cycle. Nitrogen is the key mineral in the healthy development of leaves and stems. It is also the most common deficieny in plant growth resulting in stunted growth and yellowing leaves. During the flowering cycle the ratio of nitrogen to phosphorous and potassium is decreased.
    Following a good nutrient regime should be enough to produce a high quality, vitamin rich food source. Keeping it simple means less troubleshooting should a problem occur. Creating a toxic soup of addivtives and supplements makes it very difficult to find the culprit if something does go wrong.
    The more advanced growers may wish to fine tune plant nutrition by supplementing the twenty mineral elements required for plant growth (and contained in good quality hydroponic nutrients). Natural hormones, vitamins and some rare trace elements will stimulate normal biological functions in plants. There are other products designed to help facilitate faster nutrient uptake and accelerate stem and leaf growth. Discuss the various options with your hydroponic retailer and, if it sounds too good to be true.well, you know the rest!
    Great care should be taken when using these growth boosters. Only introduce one new product per crop rotation. Try not to get carried away by the promise of bumper crops that are ready to harvest in half the regular time.
    Bloom fortifiers are useful to supplement flowering and increase essential oils in plants. Look for a fortifier with a NPK ratio of 0-50-30. This indicates that there is no nitrogen and very high levels of phosphorous and potassium. Both of these essential minerals increase the development of super blooms.
    Organic gardening practices have become very popular over the last decade. The hydroponic industry has made great strides in developing organic formulas that will work well in a hydroponic system. An organically based nutrient should be a soluble, stand-alone product that has no sediment on the bottom of its container. Be wary of organic formulas that require shaking before use. This could be an indication that the product contains sediment that will clog lines and pumps used in a hydroponic garden. Never attempt to use an organic fertilizer that is designed for soil applications in hydroponics as it may result in plants burning and lines getting blocked.
    Kelp is very safe and an excellent source of organic trace minerals. Used regularly as a foliar spray, kelp is great way to help avoid nutrient deficiencies. Kelp spray will also act as a pest deterrent.
    Regular reservoir changes every 7 to 10 days will ensure that fresh nutrients are always available to meet the demands required for healthy growth. An electro conductivity (EC) meter will help regulate the optimum amount of nutrient required. Always check pH after the nutrient solution is mixed.
    Leaching or rinsing is necessary to wash out any excess salts that remain in the growing medium. Leach about 1 week prior to harvest. Run regular tap water or reverse osmosis water through the system following the established feeding times.
    It is always wise to keep a journal of your gardening adventures. This will allow you to repeat successful harvests and avoid duplicating mistakes. Record information on a daily basis such as: Species, germination date, nutrient brand and feeding times, pH, EC, leaching date and harvest date. Don't forget to record the time and dose of any additives used.
    Keep it simple and enjoy the fruits of your labour. A hydroponic garden can be a fascinating and rewarding hobby year round.

    Sunbiz1 Well-Known Member

    Thanks for the chart, it answered my question regarding N deficiency. I didn't add enough on an in-ground, tomorrow I'll be trying to resolve that in a hurry.

    billy4479 Moderator

    order to grow the biggest buds possible, we first need to understand how plants work and how they grow. This involves what are known as the "essential" nutrients - and I know a lot of people are aware of them, but understanding their function and role in maintaining plant health is something that is frequently overlooked. A number of growth problems can be avoided with the proper balance of nutrients. I see a lot of people using nutrients and trace elements without knowing what to expect, so let's go through this really quickly:

    Nitrogen: Nitrogen is essential for proper leaf growth and color, the synthesis of amino acids, proteins, nucleic acids, and also chlorophyll. Many proteins that rely on adequate nitrogen levels are the very ones that stimulate plant growth. With the proper levels of nitrogen, your plants should have a healthy green look to them, and unhindered growth. The older leaves will show signs of nitrogen deficiencies first, so if you notice any pale yellowing at the tips of your plants, it might not be a bad idea to up the nitrogen level slightly. As with all of these nutrients, keep in mind that any adjustments you feel you have to make should be in small quantities, and most importantly, gradual.

    Phosphorus: Phosphorus is a main component of DNA/RNA synthesis, as well as the development of roots, stems, and most importantly: flowers and seeds. The flowering period is where you want to begin adjusting phosphorus levels (if you so wish to) to suit the needs of the plant - some have seen increased quality and quantity of buds; but furthermore, a generally healthy level of phosphorus throughout it's life also yields strong plants with long roots and healthy growth levels. Because it is responsible for energy exchange (via ATP/ADP), phosphorus is essential to bigger plants, bigger yields, better buds - and better genetics. Deficiency symptoms include weak stems, stunted growth of leaves/roots, and other general poor growth characteristics.

    Potassium: Potassium is responsible for the synthesis of proteins and carbohydrates, as well as the development of roots, stems, and flowers. Through the exchange of potassium ions, the stomata of a plant are able to open and close - allowing carbon dioxide to enter the plant so it may be utilized for photosynthesis. Furthermore, it helps plants resist droughts, extreme temperatures, diseases, and also helps balance the pH level by neutralizing organic anions found in the plant. However, perhaps the most important function that potassium has is to distribute sugars throughout the plant in the form of ATP. Having healthy levels of potassium will be noticeable throughout the plant; everything from healthy roots to fat buds, and the little things in between, like the rate at which photosynthesis can occur at. So if your plants aren't looking quite as healthy as they should be; if they're not reaching for the sky quite as vigorously as they could, or if your leaves are starting to turn yellow/"burn" at the edges, you may have a potassium imbalance.

    Okay, let's break here and talk about the three as a whole: Nitrogen, Phosphorus, and Potassium. N-P-K. Many soils will have composition ratios listed on the front of the bag, and there's so many to choose from, so how do you know what works best for you? Well, I can't say there's an answer that's set in stone, because every plant and strain are diverse so their needs must be tailored to. There isn't a simple solution, given how complex life is, but here are a couple of suggestions:

    For rooting/germination, try to get higher levels of phosphorus, with less N/K, because at this point in the plant's life it wants to focus on cellular reproduction and growth of roots. Plus without much chlorophyll for photosynthesis, the plant needs to rely on adenosine triphosphate (ATP) energy to carry out vital functions. Roots also respire, which means a plentiful supply of oxygen will allow the roots to breathe easier, and better growth rates can be achieved. During vegetative growth, more nitrogen can be assimilated because the plant's growth is limited to the amount of nutrients, water, and sunlight it receives. They will otherwise grow incessantly. During flowering, an increase of phosphorus, once again, will ensure good genetic transcription and maximized production of flowers.

    Before we move onto the micronutrients, there are two other things we must examine: mobile vs immobile elements. Symptoms of deficiencies, based on the element, may either appear on younger leaves or older leaves, depending on if they are mobile or not. Boron and calcium are examples of immobile elements, since they cannot be returned to the plant through the phloem after they have been used. Therefore, younger leaves will show signs of deficiencies before the older ones to. On the other hand, mobile elements such as nitrogen, phosphorus, potassium, sulfur, and magnesium will be transported to younger leaves first, so the older leaves will show signs of a deficiency first. Secondly, and quite briefly, it is important to note that soil pH is also very important in governing the absorption rates of a majority, if not all, of the nutrients. With too much of an imbalance, certain nutrients might be locked out as others are absorped in higher quantities by the plant, which could in turn cause burning and unstable growth. The first and foremost way to ensure a happy plant is to feed it the right water.

    Now let's get onto some of the secondary nutrients - often referred to as micronutrients or trace nutrients.

    Magnesium: Magnesium is known for it's role in synthesizing chlorophyll and helping activate some enzymes which are responsible for rapid growth. There are hundreds of enzymes that are activated with magnesium and you may find that deficiencies include thin stems and weak, pale leaves. It's recommended to having epsom salts around in case you need to correct the balance (magnesium sulfate will do just fine)

    Calcium: Cell growth and division, cell wall structure, cellular transportation, and enzyme activation all fall within the range of Calcium's influence. Plants grow fast, firm, and upright with the proper balance of calcium - otherwise, you may notice brown, curling leaves, and stunted growth.

    Sulfur: Sulfur is an essential plant food that helps with the production of acetyl-CoA, and is therefore helpful for energy production, enzyme/protein formation, chlorophyll formation, and to a certain extent, increased root and flower production. It is also an important factor of the chromophore; a light-detecting portion of a phytochrome, so during the flowering period, the size of your buds can be affected by a healthy dosage of Sulfur.

    Chlorine: Chlorine is involved in the osmotic transfer of water across the stomata, and it aids in photosynthesis. A single touch on any part of the plant will provide enough chlorine for it, so don't worry about supplementation.

    Zinc and Boron: Both aid in the production of sugars/carbohydrates, and are helpful in production of flowers/fruits.

    Manganese: Manganese is an example of a nutrient whose rate of absorption is based on soil pH, It helps activate certain enzymes that are essential to chlorophyll formation, so deficiency symptoms may include chlorosis between the veins on the leaves and a lack of growth capabilities.

    Molybdenum: Molybdenum helps plants fixate Nitrogen into a bio-available form, but chances are your soils are already going to have this as a part of the mixture.


    Common Deficiency Symptoms: The diagnosis may be the hardest part of determining exactly which elements are lacking in your plant; for the reason that a lot of symptoms of element deficiencies manifest themselves into physical characteristics that are extremely similar to other element deficiencies. Some of the more common ones are chlorosis, where chlorophyll production becomes hindered and the leaves will consequently turn yellow and brittle. Deficiencies of nitrogen and phosphorus may cause the accumulation of anthocyanin pigments, and thus turning leaves very dark, and sometimes adding purple hues. Potassium and manganese will both cause necrosis, or patches of dead tissue in the plant. However, one notable difference is that a manganese deficiency will cause leaf tissue between veins to die, and a potassium deficiency will kill the tips first.

    Pictures of Deficiencies





















    Phew, there we go. Please keep in mind - this is meant to be a reference not a guide to nutrition of your plants. Balancing these elements is crucial, otherwise, you may find that too much of one will limit the plant's intake ability of another, so you may start seeing something like a calcium deficiency with too much magnesium. With even a single nutrient missing you may experience hardships in how your plant grows, so it's important to pay attention to how the plant looks and feels. Learning to read your plant's symptoms will help tremendously in fixing the problems that every grower eventually experiences

    billy4479 Moderator

    Mobility of plant nutrients

    Plant nutrients which can move from places where they are stored to places where they are needed are called plant mobile. Nitrogen, phosphorus and potassium are always plant mobile nutrients. Deficiencies are noticeable first on older tissue. Plant immobile element deficiencies are noticeable first on younger tissue. Calcium and boron are always plant immobile nutrients. Sulfur, chloride, copper, zinc, manganese, iron and molybdenum are intermediate in plant mobility. Under certain circumstances the intermediate elements are mobile. Mobility in intermediate elements may be linked to the breakdown under low nitrogen conditions of amino acids and proteins in older parts of the plant, and the mobility of these organic compounds to younger parts of the plant in the phloem stream. Under good nitrogen availability, these elements are mostly immobile.
    Value of plant nutrient deficiency keys

    Use of this plant nutrient deficiency key should be considered first as the first step toward understanding deficiency symptoms in the field secondly as an educational tool to be used in conjunction with soil testing and plant analysis. Environmental stress such as drought, wet conditions, disease, heat and agchemical interactions can easily be misinterpreted as deficiency symptoms. Photographs of nutrient deficiencies are useful in diagnosis, but field experience and a knowledge of field history based on local experience is the best diagnostic aid.


    billy4479 Moderator

    Nutrient Deficiency Symptoms

    Dave Franzen
    NDSU Extension Soil Scientist

    HTML Editors: Jochum Wiersma & Tracy Allrich ​
    The preferred way to handle nutrient deficiencies is to identify annual crop needs with soil testing, perennial crop needs with plant analysis, and to correct the deficiencies before the crop is established or deficiency symptoms appear. However, soils are very variable in nutrient levels. Portions of fields low in a certain nutrient may not show up in a normal composite soil sample. The chemistry of some nutrients, such as iron and manganese, is very complex and difficult to predict with a simple soil test. Thus, deficiencies of some nutrients can sometimes appear even with a good soil testing program. Certain nutrient problems are sometimes so rare that regular soil analysis requests do not include testing for those nutrients. Nutrient deficiency symptoms are often the first clues to a nutrient problem within a field.
    Plants which are under stress show unusual growth patterns or coloration. These visual symptoms are called deficiency symptoms. Deficiency symptoms can sometimes be confused with other complex field events, such as high water tables, salt damage, disease, drought, herbicide stress and varietal differences. Deficiencies can also be so slight that they are confused with other problems. If more than one deficiency is present, one can be more dominant in its symptoms, obscuring the symptoms of the other element.
    Terminology of nutrient deficiencies


    General yellowing of the leaf tissue. A very common deficiency symptom, since many nutrients affect the photosynthesis process directly or indirectly.
    Coloration abnormalities

    Some deficiencies lower the amount of photosynthesis and chlorophyll which is produced by the plant. Other colored compounds can then become dominant. When normal nutrient sinks are not available, the plants can store up excess sugars within other compounds which have distinct colors of red, purple, or sometimes brown. The absence of chlorophyll altogether causes the plant to turn white.

    Yellowing, followed by rapid death of lower leaves, moving up the plant and giving the same appearance as if someone touched the bottom of the plants
    Interveinal Chlorosis

    Yellowing in between leaf veins, but with the veins themselves remaining green. In grasses, this is called striping.

    Severe deficiencies result in death of the entire plant or parts of the plant first affected by the deficiency. The plant tissue browns and dies. This is called necrosis. The tissue which has already died on a still living plant is called necrotic tissue.

    Many deficiencies result in decreased growth. This can result in shorter height of the affected plants.
    Functions of the 13 soil supplied essential elements


    An essential component of amino acids, and therefore all proteins. An essential component of nucleic acids, and therefore needed for all cell division and reproduction. Enzymes are specialized proteins, and serve to lower energy requirements to perform many tasks inside plants. Nitrogen is contained in all enzymes essential for all plant functions.

    A component of the compound within plants which supply the energy to grow and maintain the plant. Part of cell membranes, the structures which selectively keep out unneeded compounds and allow in those compounds which are needed for the plant cells to function correctly. A part of DNA and its relatives. Needed for cell division and for reproduction.

    Activates certain enzymes. It regulates stomate opening, which in turn regulates air flow into the leaf and transpiration of water out of the leaf. it acts to balance charge between negatively and positively charged ions within plant cells. It regulates turgor pressure, which helps protect plant cells from disease invasion. In certain plants, potassium can be replaced by sodium.

    Sulfur is a part of certain amino acids and all proteins. It acts as an enzyme activator and coenzyme (compound which is not part of all enzyme, but is needed in close coordination with the enzyme for certain specialized functions to operate correctly). It is a part of the flavor compounds in mustard and onion family plants.

    Calcium is a part of cell walls and regulates cell wall construction. Cell walls give plant cells their structural strength. Enhances uptake of negatively charged ions such as nitrate, sulfate, borate and molybdate. It balances charge from organic an ions produced through metabolism by the plant. Some enzymes are regulated by Ca-calmodulin.

    Magnesium is the central element within the chlorophyll molecule. It is an important cofactor the production of ATP, the compound which is the energy transfer tool for the plant.

    Boron is important in sugar transport within the plant. It has a role in cell division, and is required for the production of certain amino acids, although it is not a part of any amino acid.

    Molybdenum is needed for the reduction of absorbed nitrates into ammonia prior to incorporation into an amino acid. It performs this function as a part of the enzyme nitrate reductase. In addition to direct plant functions, molybdenum is also essential for nitrogen fixation by nitrogen-fixing bacteria in legumes. Responses of legumes to Molybdenum application are mainly due to the need by these symbiotic bacteria.

    Iron is a component of the many enzymes and light energy transferring compounds involved in photosynthesis.

    Zinc is a component of many enzymes. It is essential for plant hormone balance, especially auxin activity.

    Manganese is a cofactor in many plant reactions. It is essential for chloroplast production.

    Copper is a component of enzymes involved with photosynthesis.

    Plants use chlorine as chloride ion. Chloride is useful as a charge balancing ion and for turgor regulation, keeping plant cells more free of infection by disease organisms. It is essential for photosynthesis.
    Mobility of plant nutrients

    Plant nutrients which can move from places where they are stored to places where they are needed are called plant mobile. Nitrogen, phosphorus and potassium are always plant mobile nutrients. Deficiencies are noticeable first on older tissue. Plant immobile element deficiencies are noticeable first on younger tissue. Calcium and boron are always plant immobile nutrients. Sulfur, chloride, copper, zinc, manganese, iron and molybdenum are intermediate in plant mobility. Under certain circumstances the intermediate elements are mobile. Mobility in intermediate elements may be linked to the breakdown under low nitrogen conditions of amino acids and proteins in older parts of the plant, and the mobility of these organic compounds to younger parts of the plant in the phloem stream. Under good nitrogen availability, these elements are mostly immobile.
    Value of plant nutrient deficiency keys

    Use of this plant nutrient deficiency key should be considered first as the first step toward understanding deficiency symptoms in the field secondly as an educational tool to be used in conjunction with soil testing and plant analysis. Environmental stress such as drought, wet conditions, disease, heat and agchemical interactions can easily be misinterpreted as deficiency symptoms. Photographs of nutrient deficiencies are useful in diagnosis, but field experience and a knowledge of field history based on local experience is the best diagnostic aid.


    cannawizard Weed God

    *great job Billy, keep it up brah... AMC-Moderation confederation.. lolz

    billy4479 Moderator

    Here are some interesting plant problem solvers:

    Nutrient disorders are caused by too much or too little of one or several nutrients being available. These nutrients are made available between a pH range of 5 and 7 and a total dissolved solids (TDS) range of 800 to 3000 PPM. Maintaining these conditions is the key to proper nutrient uptake.
    Nutrients Over twenty elements are needed for a plant to grow. Carbon, hydrogen and oxygen are absorbed from the air and water. The rest of the elements, called mineral nutrients, are dissolved in the nutrient solution.
    The primary or macro- nutrients (nitrogen (N), phosphorus (P) and potassium (K)) are the elements plants use the most. Calcium (Ca) and magnesium (Mg) are secondary nutrients and used in smaller amounts. Iron (Fe), sulfur (S), manganese (Mn), boron (B), molybdenum (Mo), zinc (Zn) and copper (Cu) are micro-nutrients or trace elements.

    advertisement ​

    Trace elements are found in most soils. Rockwool (hydroponic) fertilizers must contain these trace elements, as they do not normally exist in sufficient quantities in rockwool or water. Other elements also play a part in plant growth. Aluminum, chlorine, cobalt, iodine, selenium, silicon, sodium and vanadium are not normally included in nutrient mixes. They are required in very minute amounts that are usually present as impurities in the water supply or mixed along with other nutrients.

    [​IMG] The nutrients must be soluble (able to be dissolved in water) and go into solution.

    Macro-nutrients Nitrogen (N) is primary to plant growth. Plants convert nitrogen to make proteins essential to new cell growth. Nitrogen is mainly responsible for leaf and stem growth as well as overall size and vigor. Nitrogen moves easily to active young buds, shoots and leaves and slower to older leaves. Deficiency signs show first in older leaves. They turn a pale yellow and may die. New growth becomes weak and spindly. An abundance of nitrogen will cause soft, weak growth and even delay flower and fruit production if it is allowed to accumulate. Phosphorus (P) is necessary for photosynthesis and works as a catalyst for energy transfer within the plant. Phosphorus helps build strong roots and is vital for flower and seed production. Highest levels of phosphorus are used during germination, seedling growth and flowering. Deficiencies will show in older leaves first. Leaves turn deep green on a uniformly smaller, stunted plant. Leaves show brown or purple spots.

    [​IMG] Phosphorus flocculates when concentrated and combined with calcium.

    Potassium (K) activates the manufacture and movement of sugars and starches, as well as growth by cell division. Potassium increases chlorophyll in foliage and helps regulate stomata openings so plants make better use of light and air. Potassium encourages strong root growth, water uptake and triggers enzymes that fight disease. Potassium is necessary during all stages of growth. It is especially important in the development of fruit.

    Deficiency signs of potassium are: plants are the tallest and appear healthy. Older leaves mottle and yellow between veins, followed by whole leaves that turn dark yellow and die. Flower and fruit drop are common problems associated with potassium deficiency. Potassium is usually locked out by high salinity. Secondary Nutrients Magnesium (Mg) is found as a central atom in the chlorophyll molecule and is essential to the absorption of light energy. Magnesium aids in the utilization of nutrients, neutralizes acids and toxic compounds produced by the plant. Deficiency signs of magnesium are: Older leaves yellow from the center outward, while veins remain green on deficient plants. Leaf tips and edges may discolor and curl upward. Growing tips turn lime green if the deficiency progresses to the top of the plant.
    Calcium (Ca) is fundamental to cell manufacture and growth. Soil gardeners use dolomite lime, which contains calcium and magnesium, to keep the soil sweet or buffered. Rockwool gardeners use calcium to buffer excess nutrients. Calcium moves slowly within the plant and tends to concentrate in roots and older growth. Consequently young growth shows deficiency signs first. Deficient leaf tips, edges and new growth will turn brown and die back. If too much calcium is applied early in life, it will stunt growth as well. It will also flocculate when a concentrated form is combined with potassium.
    Trace Elements Sulphur (S) is a component of plant proteins and plays a role in root growth and chlorophyll supply. Distributed relatively evenly with largest amounts in leaves which affects the flavor and odor in many plants. Sulphur, like calcium, moves little within plant tissue and the first signs of a deficiency are pale young leaves. Growth is slow but leaves tend to get brittle and stay narrower than normal.
    Iron (Fe) is a key catalyst in chlorophyll production and is used in photosynthesis. A lack of iron turns leaves pale yellow or white while the veins remain green. Iron is difficult for plants to absorb and moves slowly within the plant. Always use chelated (immediately available to the plant) iron in nutrient mixes.
    Manganese (Mg) works with plant enzymes to reduce nitrates before producing proteins. A lack of manganese turns young leaves a mottled yellow or brown.
    Zinc (Z) is a catalyst and must be present in minute amounts for plant growth. A lack of zinc results in stunting, yellowing and curling of small leaves. An excess of zinc is uncommon but very toxic and causes wilting or death.
    Copper (C) is a catalyst for several enzymes. A shortage of copper makes new growth wilt and causes irregular growth. Excesses of copper causes sudden death. Copper is also used as a fungicide and wards off insects and diseases because of this property.
    Boron (B) is necessary for cells to divide and protein formation. It also plays an active role in pollination and seed production.
    Molybdenum (Mn) helps form proteins and aids the plant's ability to fix nitrogen from the air. A deficiency causes leaves to turn pale and fringes to appear scorched. Irregular leaf growth may also result.
    These nutrients are mixed together to form a complete plant fertilizer. The mix contains all the nutrients in the proper ratios to give plants all they need for lush, rapid growth. The fertilizer is dissolved in water to make a nutrient solution. Water transports these soluble nutrients into contact with the plant roots. In the presence of oxygen and water, the nutrients are absorbed through the root hairs.
    Source:George Van Pattens' excellent book "Gardening: The Rockwool Book".

    Key on Nutrient Disorders

    To use the Problem-Solver, simply start at #1 below. When you think you've found the problem, read the Nutrients section to learn more about it. Diagnose carefully before making major changes.

    1) ​
    a) If the problem affects only the bottom or middle of the plant go to #2.

    b) If it affects only the top of the plant or the growing tips, skip to #10.

    If the problem seems to affect the entire plant equally, skip to #6.


    Leaves are a uniform yellow or light green; leaves die & drop; growth is slow. Leaf margins are not curled-up noticeably. » Nitrogen (N) deficiency.

    b) If not, go to #3.
    a) Margins of the leaves are turned up, and the tips may be twisted. Leaves are yellowing (and may turn brown), but the veins remain somewhat green. » Magnesium (Mg) deficiency.

    b) If not, go to #4.

    Leaves are browning or yellowing. Yellow, brown, or necrotic (dead) patches, especially around the edges of the leaf, which may be curled. Plant may be too tall. » Potassium (K) deficiency.

    b) If not, keep reading.

    Leaves are dark green or red/purple. Stems and petioles may have purple & red on them. Leaves may turn yellow or curl under. Leaf may drop easily. Growth may be slow and leaves may be small. » Phosphorous (P) deficiency.

    b) If not, go to #6.

    Tips of leaves are yellow, brown, or dead. Plant otherwise looks healthy & green.Stems may be soft » Overfertilization (especially N), over-watering, damaged roots, or insufficient soil aeration (use more sand or perlite. Occasionally due to not enough N, P, or K.

    b) If not, go to #7.


    Leaves are curled under like a ram's horn, and are dark green, gray, brown, or gold. » Over-fertilization
    (too much N).

    b) If not, go to #8.

    The plant is wilted, even though the soil is moist. » Over-fertilization, soggy soil, damaged roots, disease; copper deficiency (very unlikely).

    b) If not, go to #9.

    Plants won't flower, even though they get 12 hours of darkness for over 2 weeks. » The night period is not completely dark. Too much nitrogen. Too much pruning or cloning.

    b) If not, go to #10...
    10) ​
    a) Leaves are yellow or white, but the veins are mostly green. » Iron (Fe) deficiency.

    b) If not, #11.


    Leaves are light green or yellow beginning at the base, while the leaf margins remain green. Necrotic spots may be between veins. Leaves are not twisted. » Manganese (Mn) deficiency.

    b) If not, #12.
    12) ​
    a) Leaves are twisted. Otherwise, pretty much like #11. » Zinc (Zn) deficiency.

    b) If not, #13.

    Leaves twist, then turn brown or die. » The lights are too close to the plant. Rarely, a Calcium (Ca) or Boron (B) deficiency.

    b) If not. You may just have a weak plant.

    Solutions to Nutrient Deficiencies The Nutrients: Nitrogen - (N)
    Plants need lots of N during vegging, but it's easy to overdo it. Added too much? Flush the soil with plain water. Soluble nitrogen (especially nitrate) is the form that's the most quickly available to the roots, while insoluble N (like urea) first needs to be broken down by microbes in the soil before the roots can absorb it. Avoid excessive ammonium nitrogen, which can interfere with other nutrients. Too much N delays flowering. Plants should be allowed to become N-deficient late in flowering for best flavor.

    Mg-deficiency is pretty common since marijuana uses lots of it and many fertilizers don't have enough of it. Mg-deficiency is easily fixed with ¼ teaspoon/gallon of Epsom salts (first powdered and dissolved in some hot water) or foliar feed at ½ teaspoon/quart. When mixing up soil, use 2 teaspoon dolomite lime per gallon of soil for Mg. Mg can get locked-up by too much Ca, Cl or ammonium nitrogen. Don't overdo Mg or you'll lock up other nutrients.

    Too much sodium (Na) displaces K, causing a K deficiency. Sources of high salinity are: baking soda (sodium bicarbonate "pH-up"), too much manure, and the use of water-softening filters (which should not be used). If the problem is Na, flush the soil. K can get locked up from too much Ca or ammonium nitrogen, and possibly cold weather.

    Some deficiency during flowering is normal, but too much shouldn't be tolerated. Red petioles and stems are a normal, genetic characteristic for many varieties, plus it can also be a co-symptom of N, K and Mg-deficiencies, so red stems are not a foolproof sign of P-deficiency. Too much P can lead to iron deficiency.

    Fe is unavailable to plants when the pH of the water or soil is too high. If deficient, lower the pH to about 6.5 (for rockwool, about 5.7), and check that you're not adding too much P, which can lock up Fe. Use iron that's chelated for maximum availability. Read your fertilizer's ingredients - chelated iron might read something like "iron EDTA". To much Fe without adding enough P can cause a P-deficiency.

    Mn gets locked out when the pH is too high, and when there's too much iron. Use chelated Mn.

    Also gets locked out due to high pH. Zn, Fe, and Mn deficiencies often occur together, and are usually from a high pH. Don't overdo the micro-nutrients- lower the pH if that's the problem so the nutrients become available. Foliar feed if the plant looks real bad. Use chelated zinc.


    Causes leaf tips to appear yellow or burnt. To correct soil should be flushed with three gallons of water per one gallon of soil.
    B - BORON (B)

    Growing shoots turn grey or die. Growing shoots appear burnt. Treat with one teaspoon of Boric acid (sold as eyewash) per gallon of water.

    Ca - CALCIUM (Ca)

    Lack of calcium in the soil results in the soil becoming too acid. This leads to Mg or Fe deficiency or very slow stunted growth. Treat by foliar feeding with one teaspoon of dolomatic lime per quart of water until condition improves.

    Check Your Water
    Crusty faucets and shower heads mean your water is "hard," usually due to too many minerals. Tap water with a TDS (total dissolved solids) level of more than around 200ppm (parts per million) is "hard" and should be looked into, especially if your plants have a chronic problem. Ask your water company for an analysis listing, which will usually list the pH, TDS, and mineral levels (as well as the pollutants, carcinogens, etc) for the tap water in your area. This is a common request, especially in this day and age, so it shouldn't raise an eyebrow.

    Regular water filters will not reduce a high TDS level, but the costlier reverse-osmosis units, distillers, and de-ionizers will. A digital TDS meter (or EC = electrical conductivity meter) is an incredibly useful tool for monitoring the nutrient levels of nutrient solution, and will pay for itself before you know it. They run about $40 and up.

    General Feeding Tips
    Pot plants are very adaptable, but a general rule of thumb is to use more nitrogen & less phosphorous during the vegetative period, and the exact opposite during the flowering period. For the veg. period try a N:P:K ratio of about 10:7:8 (which of course is the same ratio as 20:14:16), and for flowering plants, 4:8:8. Check the pH after adding nutrients.

    If you use a reservoir, keep it circulating and change it every 2 weeks. A general guideline for TDS levels is as follows: seedlings = 50-150 ppm; unrooted clones = 100-350 ppm; small plants = 400-800 ppm; large plants = 900-1800 ppm; last week of flowering = taper off to plain water. These numbers are just a guideline, and many factors can change the actual level the plants will need. Certain nutrients are "invisible" to TDS meters, especially organics, so use TDS level only as an estimate of actual nutrient levels. When in doubt about a new fertilizer, follow the fertilizer's directions for feeding tomatoes. Grow a few tomato or radish plants nearby for comparison.

    The pH of water after adding any nutrients should be around 5.9-6.5 (in rockwool, 5.5-6.1) . Generally speaking, the micro-nutrients (Fe, Zn, Mn, Cu) get locked out at a high pH (alkaline) above 7.0, while the major nutrients (N, P, K, Mg) can be less available in acidic soil or water (below 5.0). Tapwater is often too alkaline. Soils with lots of peat or other organic matter in them tend to get too acidic, which some dolomite lime will help fix. Soil test kits vary in accuracy, and generally the more you pay the better the accuracy. For the water, color-based pH test kits from aquarium stores are inexpensive, but inaccurate. Invest in a digital pH meter ($40-80), preferably a waterproof one. You won't regret it.

    Other Things.

    Cold weather (below 50F/10C) can lock up phosphorous. Some varieties, like equatorial sativas, don't take well to cold weather. If you can keep the roots warmer, the plant will be able to take cooler temps than it otherwise could.

    If the lights are too close to the plant, the tops may be curled, dry, and look burnt, mimicking a nutrient problem. Your hand should not feel hot after a minute when you hold it at the top of the plants. Raise the lights and/or aim a fan at the hot zone. Room temps should be kept under 85F (29C) -- or 90F (33) if you add additional CO2.

    Thin, shriveled leaves can be from low humidity. 40-80 % is usually fine.

    Mold and fungus
    Dark patchy areas on leaves and buds can be mold. Lower the humidity and increase the ventilation if mold is a problem. Remove any dead leaves, wherever they are. Keep your garden clean.

    White spots on the tops of leaves can mean spider mites underneath.

    Foliar sprays can have a "magnifying glass" effect under bright lights, causing small white, yellow or burnt spots which can be confused with a nutrient problem. Some sprays can also cause chemical reactions.

    Insufficient light
    Tall, stretching plants are usually from using the wrong kind of light.. Don't use regular incandescent bulbs ("grow bulbs") or halogens to grow cannabis. Invest in fluorescent lighting (good) or HID lighting (much better) which supply the high-intensity light that cannabis needs for good growth and tight buds. Even better, grow in sunlight.

    yellowing leaves on unrooted clones can be from too much light, or the stem may not be firmly touching the rooting medium. Turn off any CO2 until they root. Too much fertilizer can shrivel or wilt clones - plain tap water is fine.

    IVIars Active Member

    Great info.

    But please remove that stupid chart on your first post. Just because a plant is showing a deficiency of n or p (examples) doesn't mean n or p is causing it. A mulder chart shows the interrelationships the nutrients have with one another.
    billy4479 likes this.

    POUND TOWN Active Member

    so would i be right in assuming this is phosphorus related?
    brown spots start along center of leaf and spread out until leaf is dead brown
    this is the dominant deficiency that has been spreading

    see but this is what i dont get..
    this leaf looks similar but actually the browning start along the outside on the leaf tips and works its way to the center of the leaf
    there is nothing on the center of the leaf

    then this one is just natural yellowing i think

    ALL off the same plant
    what gives??????

    zo0t New Member

    y0 billy br() which books iz dat u post pictures from ? i wanna dewnlad

    i think its The Indoor Bible i gotz da indoor outdour bible they different

    dapio Active Member

    it seems hard to determine a deficiency based on reading that if one deficiency exist it may cause a deficiency of something else in itself seems confusing anyone out there figured out a easy way to diagnose symptoms?

    zo0t New Member

    0 wtf iz dis nonsense br0 u haz smoken too much too much

    zo0t New Member

    • something else in itself


    dapio Active Member

    lol like say a deficiency in iron is causing one in magnesium like a domino effect?
    Uncle Ben

    Uncle Ben Well-Known Member

    That is a valid point. A deficiency of one can mask as a deficiency of another. IOW, you may think you have a Fe deficiency when you actually have a Zn.

    I've preached nutrient antagonism for years. Here's a good link on it.

    Also, a thread like this will drive a noob crazy!

    KUShSOurSMOKEr Active Member

    nice post uncle ben thanks!

    billy4479 Moderator

    Elemental Interactions
    As one might imagine, nutrients often do not work alone in their effects on plant growth and development. Quite often, an excess of one nutrient can cause a deficiency of another. This effect is called nutrient antagonism. For example, an excess of potassium in the soil solution can interfere with magnesium utilization, and in effect causes a physiological magnesium deficiency even where the the soil supply of magnesium has been shown to be adequate. Another common antagonistic relationship is that of excessive phosphorus and its effects on zinc, iron and copper uptake. Some common antagonistic relationships are listed in the following table.
    [TABLE="align: center"]
    [TD="width: 40%"]
    Elements in Excess​
    [TD="width: 60%"]
    Nutrients Usually Affected​
    [TD]Potassium, Calcium[/TD]
    [TD]Nitrogen, Calcium, Magnesium[/TD]
    [TD]Zinc, Iron, Copper[/TD]
    [TD]Boron, Magnesium, Phosphorus[/TD]
    [TD]Calcium, Potassium[/TD]
    [TD]Manganese [/TD]
    [TD]Iron, Molybdenum, Magnesium[/TD]
    [TD]Molybdenum, Iron, Manganese, Zinc[/TD]
    [TD]Iron, Manganese[/TD]
    [TD]Copper, Iron[/TD]
    [TD]Sodium [/TD]
    [TD]Potassium, Calcium, Magnesium[/TD]
    [TD]Ammonium Ion [/TD]
    [TD]Calcium, Copper[/TD]
    Fortunately, nutrients often work together in many instances to enhance one another. For example, use of readily available water-soluble phosphorus enhances utilization of nitrogen, and vice versa. Most nutrients are more efficiently utilized when in proper balance in the soil solution.
    Using TotalGro water soluble plant foods at rates appropriate for the species being grown allows the grower to maintain the plantings at optimum growth rates for maximum marketability and profit. All plants grow best within their own well-defined nutritional boundaries. These boundaries are species-and-variety-specific, such that when a particular plant is exposed to either the lower or upper limit, plant vigor and performance falter. This property of plant response to nutrient supply is better known as the Principle of Limiting Factors. Basically, this principle says that the level of crop production can never be greater than that allowed by the most limiting essential plant nutrients .

    billy4479 Moderator

    Good to see this threads still alive ...

Share This Page