Hormone --A biochemical product of a specific cell or tissue that causes a change or activity in a cell or tissue located elsewhere in an organism.

Hydroponics -- the growing of plants without soil, instead using a medium like clay pebbles, rockwool-floc or perlite and vermiculite mixture.

Humus -- a complicated material formed during the breakdown of organic matter. One of its components, humic acid, provides many binding sites for plant nutrients, such as calcium, iron, potassium, sulfur and phosphorus. These nutrients are stored in the humic acid molecule in a form readily available to plants, and are released when the plants require them.

Hybrid -- Often refers to a plant or variety that has been developed by interbreeding two or more varieties, species, or genera

IBL - Imbred line, a homogeneous strain that shows uniform growth characteristics from seed

Indica -- Indica is a great plant to grow indoors as well as outdoors due to its low lighting requirements and tight internode spacing, also offering resistance to fungus and pests, early maturation tendencies, and dense flower production. Indica's come from colder climates exhibiting the traits described above by acclimating to the environment from whence they came. Their stout stature and extremely wide leaflets make them easy to identify. An Indica generally produces a hard hitting, tiresome, sedative stone, and will take around 45 to 60 days to finish flowering.

Leggy --If seedlings and plants do not get enough sunlight, they grow tall and thin stalks as they seek sunlight. These "leggy" plants have a difficult time supporting the weight of the plant and is easily damaged.

Light-burn - When the heat from a light burns the plant.

Lumens -- one lumen is equal to the amount of light emitted by one candle that falls on one square foot of surface one foot away. Lamp Lumen Data

LST - Acronym for Low-Stress Training, the technique of manipulating the branches in order to reduce plant height, expose certain branches to light, and/or distribute hormones to lower branches of the plant to encourage larger buds.

Macronutrients --For a plant, there are nine major elements essential for healthy growth; these are called macronutrients. They are: carbon, hydrogen, and oxygen (which are all three derived from air and water); and nitrogen, phosphorus, potassium, calcium, sulfur, and magnesium (from the soil).

Micronutrients --There are about eight nutrients essential to plant growth and health that are only present in very small quantities. These are manganese, boron, copper, iron, chlorine, cobalt, molybdenum, and zinc.

Medium -- A soil or soil-less mix used to start or re-plant houseplants, flowers, vegetables, and other plants

Mottling of Leaves -- Discoloration or spotting of leaves.

MV -- Mercury Vapor is the type of lights that were used for streetlights many years ago. Not very good for growing because it doesn't provide enough of the right kind of light spectrum. While they do provide a littleof the blue spectrum, MV also produces too much heat to get very close to a plant, and are very inefficient to operate.

MH -- The Metal Halide is a very good source of the white/blue spectrum of light that is ideal for vegetative growth. Many growers use MH during the vegetative phase. MH is bright and cost efficient to operate, but not as efficient as HPS lights. Most commonly used sizes are 400 watt and 1000 watt. Works best when used in combination with HPS lights.

Necrosis - Death of parts of the plant, usually refers specifically to the leaves.

Node -- The point on a stem where a leaf is attached or has been attached; a joint

NPK ?/b> The elemental symbol for nitrogen is N; for phosphorus it's P; for potassium it's K. All three of these elements are essential for plant growth and are considered macronutrients. N, P, and K are the three principal ingredients in most fertilizers. The NPK ratio is shown by three numbers, such as 2-1-1, that reflect the percentage of each.

Nute-burn - the result of feeding a plant an excess of fertilizer.

Organic Nutrients - Natural, non-synthetic nutrients.

Peat moss --The partially decomposed remains of mosses harvested commercially from the wild. Though difficult to wet initially, peat moss can absorb up to 25 times its own weight in water and is therefor valued as a an organic soil amendment. Peat moss is acidic --with a pH of about 3 or 4.0-- and should only be used around acid-loving plants or to help lower the pH of alkaline soils.

Perlite -- a unique volcanic mineral which expands from four to twenty times its original volume when it is quickly heated to a temperature of approximately 1600-1700 degrees F. This expansion is due to the presence of two to six percent combined water in the crude perlite rock which causes the perlite to pop in a manner similar to that of popcorn.

When expanded, each granular, snow-white particle of perlite is sterile with a neutral pH and contains many tiny, closed cells or bubbles. The surface of each particle is covered with tiny cavities which provide an extremely large surface area. These surfaces hold moisture and nutrients and make them available to plant roots. In addition, because of the physical shape of each particle, air passages are formed which provide optimum aeration and drainage. Because perlite is sterile, it is free of disease, seeds, and insects.

Perlite has been used for many years throughout the world for soil conditioning and as a component of growing mixes with materials such as peat moss or bark. Extensive studies have shown that the unique capillary action of perlite makes it a superior growing media for hydroponic cultures.

Among the many uses of perlite today are propagation and seed cultivation, plug production and transplants, interiorscape and planter growing, composting,

PH -- the measure of soil's acidity or alkalinity, measured on a scale of 1 to 14. Water is considered neutral at PH 7. PH levels below 7 are classified as acidic, or "sour". Levels above 7 are basic, alkaline or "sweet". Most plants prefer a slightly acidic soil pH of 6.0 to 6.5.

Phenotype - generally the characteristics the plant shows, mostly sativa or mostly indica traits, although theres quite alot more that i cant think of off the top of my head (stuff like tall/short, wide/skinny leaves, high/low THC content percentage (or something like that))

Phloem: Nutrient conducting tissue.

Photoperiod - AKA lighting schedule, it is the number of hours of light and darkness the plant is exposed to. Usually expressed as a fraction. Ex: 18/6 = 18 hours of light, and 6 hours of darkness

Photosynthesis: Biochemical process in which light energy is absorbed by chlorophyll, and is used to fuel the building of sugar molecules.

Pistil - a hair-like protrusion from the nodes/buds of a female plant, also a precursor to the buds themselves. Pistils turn from white to brown as the buds mature.

Potash -- Broadly, potash describes any material containing potassium. More specifically, though, potash is potassium carbonate derived from wood ashes. The term potash comes from the process of extracting lye from wood ashes in iron pots

PPM - Acronym for Parts Per Million, this term is used most in hydroponics to measure the amount of nutrients given to a plant.

Rock Wool ? Mineral or rock wool has been used extensively in Europe and is recently finding applications in the U.S. greenhouse market. Like perlite and vermiculite, it originates from a natural mineral (alumino silicates with some calcium and magnesium) that is heated to 2,700?F to form fibers that are used to make blocks or cubes as a finished product. Blocks or slabs of rock wool are used extensively by hydroponic growers of greenhouse vegetables. Rock wool typically has an alkaline pH, is sterile and chemically inert.

Regenerate - AKA re-vegging, refers to the act of putting a plant back into the growth cycle after harvesting the flowering buds off of the plant, in order to bud the plant again or to take clones off of the plant.

Root Bound --A condition where a plant or seedling's roots have grown compacted and entwined in the pot and has no room to grow. This condition results in stunting the plants growth and potential. The solution is a larger pot or transplanting outdoors.

Ruderalis -- Ruderalis is not a very good choice for flower production, indoors or out. Despite maintaining a short stature, growing only one to five feet tall, and maturing rather quickly, Ruderalis just doesn't produce the yield or quality one looks for in their flowers. A slight light cycle reduction can trigger a sprout with as little as 2 to 3 leaf sets to flower. Ruderalis spontaneously initiates flowering a few weeks after sprouting, and will not produce decent flowers unless the photoperiod provides around 18 to 19 hours of light. Even then, the yield and quality are less than desirable, incomparable to that of the Sativa or Indica sub-species.