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Hydroponic Dictionary

Courtesy of Maximum Yield Magazine – Author Unknown

Don comes home after working late at the office. He slides into bed next to his wife and gives her the universal gesture for “I am a man that wants some” (The indiscriminate sleeping grope.) His wife wakes up and Don gives her his most disarming smile in the dark. “Hey honey … are you up for getting a little frisky?” After a few moments of silence, Don’s wife flicks on the lamp on the bedside table and turns to face her husband.

“Well, honey, it would appear that the co-tangent of the horizontal aperture of time allowing for said endeavors to take place has been over-ridden by self-appointed desires to alleviate personal exhaustion through an extended period of REM state graded unconsciousness.”

“I don’t get it?” replied Don in bewilderment.

“Exactly!” replied his wife who then flicked out the light.

Sometimes the most exhaustive part of learning anything new is being bombarded by unfamiliar words and terminology. This unfamiliarity can sometimes dissuade a person from giving his or her best effort, or applying themselves at all.

Reading about hydroponics can seem incredibly daunting to any new indoor gardener, as the terminology involved is quite vast. Assembled here is a thorough list of the most commonly used terms in the industry, and their definitions. Give it a quick read through, or just keep it handy while you are perusing any other publications.

– A –

  • ACID – an acidic solution has a pH below 7
  • AERATION – directly supplying roots and grow medium with air or oxygen
  • ALGAE – any of various chiefly aquatic, eukaryotic, photosynthetic organisms, ranging in size from single-celled forms to the giant kelp
  • ALKALINE – a term describing a grow medium or nutrient solution with a high pH (over 7)
  • AMPERE (AMP) – this is the unit used to measure strength of an electric current

– B –

  • BACTERIA – any of the unicellular prokaryotic microorganisms of the class Schizomycetes, which vary in terms of morphology, oxygen and nutritional requirements, and motility, and may be free-living, saprophytic, or pathogenic in plants or animals
  • BALLAST – a device used to regulate flow of electricity to match the needs of a specific bulb
  • BLOOM – (1) the flower of a plant (2) the action of a plant’s flower reaching maturity
  • BLOSSOM BOOSTER – a fertilizer with a high phosphorous rating which increases flower yield
  • BOLT – a plant which has gone to seed prematurely
  • BUD – a small protuberance on a stem or branch, sometimes enclosed in protective scales and containing an undeveloped shoot, leaf, or flower
  • BURN – leaf tips which turn noticeably dark from excess fertilizers or salts

– C –

  • CANOPY – the uppermost reaches of your crop; those leaves most readily available to the light source
  • CARBON DIOXIDE (CO2) – a colourless, odourless, tasteless gas in the air necessary for plant life. It occurs naturally in the atmosphere at .03%
  • CELL DIVISION – The process by which a cell divides to form two daughter cells. Upon completion of the process, each daughter cell contains the same genetic material as the original cell and roughly half of its cytoplasm
  • CHITIN – a tough, protective, semitransparent substance, primarily a nitrogen-containing polysaccharide, forming the principal component of arthropod exoskeletons and the cell walls of certain fungi
  • CHLOROSIS – a sick plant displaying yellowing leaves due to a sub standard chlorophyll process; commonly caused by nutrient deficiency or imbalanced pH
  • CLONE – a plant which has been produced through asexual reproduction (i.e. – cuttings, layerings, and tissue culture)
  • CONDITIONING – the method used to bring an inert growing medium to optimum pH levels, such as soaking new rockwool in an acidic solution to lower the pH from 8.0 to 5.5
  • COTYLEDON – a leaf of the embryo of a seed plant, which upon germination either remains in the seed or emerges, enlarges, and becomes green. Also called seed leaf
  • CULTIVATION – the act of processing the fruit of a mature plant
  • CYTOKININ – any of a class of plant hormones that promote cell division and growth and delay the senescence of leaves

– D –

  • DAMPING OFF FUNGUS – disease which attacks young seedlings and cuttings causing them to rot at the base. This is generally caused by over watering.
  • DISSOLVED SOLIDS – the amount of dissolved solids, usually fertilizer salts, that are measured in parts per million
  • DRIP SYSTEM – an efficient water delivery system which employs a plumbed main hose filtering nutrient through various drip emitters, one drop at a time.

– E –

  • ELECTRICAL CONDUCTIVITY – the ability of a solution to carry electrical energy as a result of the elements and compounds in the solution

– F –

  • FERTILIZER – see nutrient
  • FLOOD TABLE – a large flat, walled basin used to hold and support grow medium and plants. Nutrient is then flooded into the basin at regular intervals
  • FOLIAR FEEDING – using a mister or spray bottle to deliver fertilizer solution directly to the foliage
  • FUNGICIDE – a product which destroys or inhibits fungus
  • FUNGUS GNATS – minute, blackish, gregarious flies destructive to mushrooms and seedlings

– G –

  • GERMINATION – the process of causing the initiation of a plant from seed
  • GRAFTING –uniting (a shoot or bud) with a growing plant by insertion or by placing in close contact
  • GROW MEDIA / MEDIUM – the material used to support a plant’s root system and store nutrient solution in a hydroponic garden
  • GUANO – a substance composed chiefly of the dung of sea birds or bats, accumulated along certain coastal areas or in caves and used as fertilizer

– H –

  • HALOGEN – any of the elements chlorine, bromine, iodine and astatine existing in a free state. Halogens are in the arc tube of a halide lamp
  • HARDEN OFF – to gradually acclimatize a plant to a harsher environment. A seedling must be hardened off before planting outdoors
  • HID – High Intensity Discharge. This generally applies to the light bulbs used in hydroponic gardens
  • HOOD – the reflective cover of an HID lamp
  • HOR – abbreviation for Horizontal. This is commonly stamped on some HID bulbs to provide instructions as to how they should be mounted
  • HORMONE – chemical substance that controls the growth and development of a plant
  • HUMIDITY – wetness in the atmosphere
  • HUMUS – a brown or black organic substance consisting of partially or wholly decayed vegetable or animal matter that provides nutrients for plants and increases the ability of soil to retain water
  • HYBRID – an offspring created by combining two plants of different breeds, variety or genetic make-up
  • HYDRATED LIME – instantly soluble lime, used to raise or lower pH
  • HYDROPONICS – cultivation of plants in nutrient solution rather than in soil
  • HYGROMETER – instrument used to measure the relative humidity in the atmosphere

– I –

  • INTENSITY – the magnitude of light energy per unit. Intensity diminishes as light travels away from the source

– K –

  • KILOWATT-HOUR – the measure of electricity used per hour. Ex: a 1000 watt HID uses one kilowatt per hour

– L –

  • LEAF CURL – leaf malformation indicative of over watering, over-fertilizing, lack of magnesium, insect damage, fungus damage or negative tropism
  • LIGHT CYCLE – see PHOTOPERIOD
  • LIGHT METER – a device used to calculate and measure the effective light in a tested area
  • LIGHT MOVER – an apparatus designed to simulate a natural horizon by slowly changing the position of a lamp and its influence
  • LUMEN – measurement of light output. One lumen is equal to the amount of light emitted by one candle that falls on one square foot of surface located one foot away from the candle

– M –

  • MACRO-NUTRIENT – one or all of the primary nutrients N-P-K or the secondary nutrients magnesium and calcium
  • MAXIMUM YIELD MAGAZINE – the number one source for the latest information pertaining to the hydroponics industry
  • MICRO-NUTRIENT – also referred to as trace elements, which includes the minerals S, Fe, Mn B, Mb, An and Cu
  • MICROBIAL – a minute life form; a microorganism, especially a bacterium that causes disease
  • MODULAR HYDROPONICS – the method of growing plants hydroponically in which each individual plant has its own contained grow medium and structure
  • MONOCHROMATIC – producing only one colour

– N –

  • NEMATODE – unsegmented worms with elongated rounded bodies pointed at both ends; mostly free-living but some are parasitic
  • NFT – Nutrient Film Technique. Nutrient is fed into grow tubes where the roots draw it up. A thin film of nutrient allows the roots to have constant contact with the nutrient and the air layer above at the same time
  • NITROGEN (N) – a nonmetallic element that constitutes nearly four-fifths of the air by volume, occurring as a colorless, odorless, almost inert diatomic gas, N2, in various minerals and in all proteins and used in a wide variety of important manufactures, including ammonia, nitric acid, TNT, and fertilizers. Atomic number 7; atomic weight 14.0067; melting point -209.86°C; boiling point -195.8°C; valence 3, 5
  • NUTRIENT – plant food, essential elements N-P-K, secondary elements and trace elements which are fundamental to sustaining plant life
  • NUTRIENT DEFICIENCIES – low and improper levels of nutrient being supplied to a plant

– O –

  • ORGANIC – of, marked by, or involving the use of fertilizers or pesticides that are strictly of animal or vegetable origin

– P –

  • pH – a scale from 1 to 14 that measures acid to alkaline balance.
  • PARABOLIC REFLECTOR – a concave reflector with a series of honeycombed panels used to reflect light
  • PERLITE – (1) a sand or volcanic glass, expanded by heat, which holds water and nutrients on its many irregular surfaces (2) mineral soil amendment
  • PHOSPHOROUS (P) – of, relating to, or containing phosphorus, especially with valence 3 or a valence lower than that of a comparable phosphoric compound
  • PHOTOPERIOD – the relationship between the length of light and dark in a 24 hour period
  • PHOTOSYNTHESIS – the process by which plants use light energy to collect carbon dioxide from the atmosphere and convert it to chemical energy in the form of sugar
  • POLLINATION – the transfer of pollen from a stamen to a pistil. This process is often enhanced by environmental manipulation, plant movement through shaking or vibration or the introduction of bees into the growing area
  • POLYPLOID – an organism with more than two sets of chromosomes
  • POTASSIUM (K) – a soft, silver-white, highly or explosively reactive metallic element that occurs in nature only in compounds. It is obtained by electrolysis of its common hydroxide and found in, or converted to, a wide variety of salts used especially in fertilizers and soaps. Atomic number 19; atomic weight 39.098; melting point 63.65°C; boiling point 774°C; specific gravity 0.862; valence 1
  • PREDATORY INSECT – any variety of insect introduced into a grow area used to combat pests or detrimental infestations
  • PROPOGATE – (1) Sexual – to produce a seed by breeding different male and female flowers (2) Asexual – to produce a plant by taking cuttings
  • PRUNING – to cut off or remove dead or living parts or branches of a plant to improve shape or growth
  • PYRETHRUM – natural insecticide made from the blossoms of various chrysanthemums

– R –

  • REFLECTOR – the highly reflective, smooth finished hood placed above a lamp to more efficiently direct its light
  • RESERVOIR (or RES) – any container of a variety of constructions which holds water in reserve for use
  • REVERSE OSMOSIS (R/O) – water which has had all of its contaminates and salts removed
  • ROCKWOOL – inert, soil less growing medium consisting of thin strand-like fibres made from rock

– S –

  • SECONDARY NUTRIENTS – Calcium (Ca) and magnesium (Mg)
  • SEEDLING – a young plant that is grown from a seed
  • SHORE FLY – any of numerous minute black flies of the family Ephydridae, living in damp or marshy places
  • SPIDER MITE – any of various small red mites of the family Tetranychidae that feed on vegetation, causing damage to the leaves
  • STIMULATOR – any product used to specifically increase one designated area of a plant’s growth cycle
  • STRESS – the effect a plant faces when it is subjected to a detrimental environment
  • SYSTEMIC – a term used in reference to a disease within the plant tissue, not initiated from the external cells. This also refers to materials and compounds which are taken up or absorbed by the plant and designed to fight disease

– T –

  • THRIPS – any of various minute insects of the order Thysanoptera, having usually four narrow wings fringed with hairs, and many of which are major pests of various plants and trees
  • TRACE ELEMENT – a chemical element required in minute quantities by an organism to maintain proper physical functioning

– U –

  • UNIFORM GROWTH – ensuring the entirety of the crop receives equal environmental stimulation resulting in equal growth of all plants

– V –

  • VERMICULITE – mica processed and expanded by heat

– W –

  • WETTING AGENT – compound that reduces the droplet size and lowers the surface tension of the water, making it wetter
  • WHITEFLY – any of various small whitish homopterous insects of the family Aleyrodidae, having long wings and a white waxy body, often injurious to plants
  • WICK – part of a passive hydroponic system using a wick suspended in the nutrient solution; the nutrients pass up the wick and are absorbed by the medium and roots
  • WORM CASTINGS – the nutrient rich fertilizer created by earthworms