- A -
ACID
A sour substance: An acidic solution has a pH below 7
AERATION
Supplying soil and roots with air or oxygen.
ALKALINE
Refers to medium or nutrient solution with a high pH: Any pH over 7 is considered alkaline
AMPERE (AMP)
The unit used to measure the strength of an electric current: A 20-amp circuit is overloaded when drawing more that 17 amps
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- B -
BOLT
Term used to describe a plant that has run into seed prematurely
BORON
Boron is an element recorded on the periodic table as “B”. Young leaves that are scorched at tips or margins may indicate a plant with inadequate amounts of boron.
BRICK SHARDS
Broken brick has been used in the place of gravel. However, may alter the pH balance and has to be cleaned between uses.
BURN
Leaf tips that turn dark from excess fertilizer and salt burn
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- C -
CALCIUM
Is a metallic element and is essential constituent of leaves. Young stems and new leaves will die in plants that are deficient in calcium. Noted by a “Ca” on the periodic table.
CARBON DIOXIDE (CO2)
A colourless, odourless, tasteless gas in the air necessary for plant life. Occurs naturally in the atmosphere at .03%
CHLOROSIS
The condition of a sick plant with yellowing leaves due to inadequate formation of chlorophyll: Chlorosis is caused by a nutrient deficiency, usually iron or imbalanced pH.
CLONE
A plant produced through asexual reproduction including, but not limited to, cuttings, layering and tissue culture
COCO COIR
A compressed medium created from the husks of coconuts. Coco coir is available in bags as well as slabs. Some types of Coco coir are very high in sodium (salt) due to the nature of Coconut Palms growing on island environments and being processed in the salty air.
CONDITIONING
To soak new Rockwool in an acidic solution to lower the pH from 8,0 to 5.5
COPPER
“Cu” is the symbol for copper on the periodic table. Copper is one of the most important metals. Plants that are lacking copper will have leaves that appear dark green or blue. The edges of the leaves will curl upward and young leaves will permanently wilt.
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- D -
DAMPING OFF FUNGUS
Disease that attacks young seedlings and cuttings causing stem to rot at base: Over watering is the main cause of damping-off
DIAHYDRO
Natural sedimentary rock medium. It contains fossilized shells of algae (diatoms) and is highly absorbent, porous and particularly high in Silica (87-94%). Silica is essential component for the growth of plans and strengthening cell walls.
DISSOLVED SOLIDS
The amount of dissolved solids, usually fertilizer salts, that are measured in water in parts per million
DRIP SYSTEM
A very efficient watering system that employs a main hose with small water emitters. Water is metered out of the emitters, one drop at a time
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- E -
ELECTRICAL CONDUCTIVITY (EC)
The ability of a solution to carry electrical energy as a result of the elements and compounds in the solution
EXPANDED CLAY
A type of medium consisting of small, irregularly shaped baked spheres of clay. They are porous and their uneven shape provides for balance between air, space and nutrient solution. This medium is suitable for hydroponic systems where nutrients are carefully controlled in the water. Can be reused if the clay is cleaned between crops.
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- F -
FOLIAR FEEDING
Misting fertilizer solution which is absorbed by the foliage
FUNGICIDE
A product that destroys or inhibits fungus
FUNGUS: DAMPING OFF FUNGUS
Disease that attacks young seedlings and cuttings causing stem to rot at base: Over watering is the main cause of damping-off
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- G -
GERMINATION
The process of causing the initiation and development of a plant from seed
GRAVEL
Usually the same type used in aquariums, though any small gravel can be used, provided it is washed prior to use. It is inexpensive, drains well, won’t become waterlogged, and easy to keep clean. It is heavy and if your system doesn’t provide continuous water, the roots may dry out.
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- H -
HALOGEN
Any of the elements flowering, 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 more harsh environment. A seedling must be hardened-off before planting outdoors
HID
High Intensity Discharge (referring to light bulbs used in hydroponic gardens)
HOOD
Reflective cover of a HID lamp: A large, white Hood is very reflective
HOR
The abbreviation stamped on some HID bulbs meaning they may be burned in a horizontal position
HORMONE
Chemical substance that controls the growth and development of a plant. Root-inducing hormones help cuttings root
HYBRID
An offspring from two plants of different breeds, variety or genetic make-up
HYDRATED LIME
Instantly soluble lime, used to raise or lower pH
HYDROPONIC
Taken from two Greek words meaning “water working”
HYGROMETER
Instrument for measuring relative humidity in the atmosphere: A hygrometer will save time, frustration and money
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- I -
INTENSITY
The magnitude of light energy per unit: Intensity diminishes the farther away from the source
IRON
Notated by “Fe” on the periodic table, it is an element that is essential in plant life. Leaf tissue in plants that are deficient in iron will be yellow while the veins remain green.
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- K -
KILOWATT-HOUR
Measure of electricity used per hour: A 1000 watt HID uses one kilowatt per hour
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- L -
LEAF CURL
Leaf malformation due to over watering, over fertilization, lack of magnesium (Mg), insect or fungus damage or negative tropism
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 one candle.
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- M -
MACRO-NUTRIENT
One or all of the primary nutrients nitrogen (N), phosphorus (P), and potassium (K) or the secondary nutrients magnesium (Mg) and calcium (Ca)
MAGNESIUM
Is an alkaline earth metal noted by “Mg” on the periodic table. Plants deficient in magnesium will have leaves that turn yellow along the tips, margin and between the veins. The lower leaves will wilt.
MANGANESE
An important trace mineral that is notated by “Mn” on the periodic table. Plants needing manganese will have stunted growth and the lower leaves will have a checkered pattern of yellow and green.
MEDIA or MEDIUM
Used to stabilize the roots of the plant in hydroponic systems. May be gravel, sand, rock wool, perlite, vermiculite or other.
MICRO-NUTRIENT
Also referred to a “trace elements” including Sulphur (S), Iron (Fe), Manganese (Mn), Boron (B), and Copper (Cu)
MOLYBDENUM
A transitional metal, molybdenum is documented on the periodic table with “Mo”. Leaves that are stunted, pale green and malformed indicate a deficiency of this element.
MONOCHROMATIC
Producing only one color: LP sodium lamps are monochromatic
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- N -
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
Noted by an “N” on the periodic table. Nitrogen is a non-metallic element. It makes up about 78% of the atmosphere. Plants that are deficient in Nitrogen are light green in color; lower leaves are yellow and their growth is stunted.
NUTRIENT
Plant food, essential elements nitrogen (N), Phosphorus (P), Potasium (K), secondary and trace elements fundamental to plant life
NUTRIENTS, SECONDARY
Calcium (Ca) and magnesium (Mg)
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- P -
pH
A scale from 1 to 14 that measures the acid to alkaline balance of a growing medium (or anything): In general plants grow best in a range of 6 to 6.8 pH 6.3 is considered ideal. If the pH is not within the acceptable range nutrients may not be absorbed to maximum capacity
PERLITE
Sand or volcanic glass, expanded by heat, holds water and nutrients on its many irregular surfaces. Used in loose or plastic sleeves immersed in water. Similar properties to vermiculite but generally holds more air and less water. In flood and drain systems if can float. Also is a mineral soil amendment to decrease soil density.
PHOSPHORUS
Noted by a “P” on the periodic table. Phosphorus is commonly misspelled “phosphorous”. It is an essential component of living systems. Plants lacking Phosphorus will be bluish-green, often developing a red or purple hue. Lower leaves may be a yellow that will dry to a greenish-brown to black color. The growth of the plant may be stunted.
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. Often enhanced by environmental manipulation , plant movement through shaking or vibrating or the introduction of bees into the growing area
POTASSIUM
An alkali metal noted as “K” on the periodic table. It is an essential component for plant growth and is found in most soils. Leaves of plants that are deficient in potassium will have a papery appearance and dead areas along the edges. Growth may be stunted.
POLYSTYRENE PACKING PEANUTS
Extremely lightweight(can be too lightweight), cheap and readily available, these drain well and are mainly used in closed tube systems. Biodegradable ones may not be used as they will become a sludge when mixed with water.
PROPAGATE
1 Sexual - produce a seed by breeding different male and female flowers
2 Asexual - to produce a plant by taking cuttings
PYRETHRUM
Natural insecticide made from the blossoms of various chrysanthemums
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- R -
RESERVOIR
Any container of a variety of constructions which holds water in reserve for use
REVERSE OSMOSIS (R/O)
Water that has had all contaminates and salts removed.
ROCKWOOL
Inert, soil less growing medium. Made from basalt rock, it is heat-treated at high temperatures then spun back like a candy floss. May come in cubes, blocks, slabs, granulated or flock. When it is dry, do not inhale particles – may carry heath risk. Most common medium.
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- S -
SAND
A cheap and readily available medium. However, it is heavy and doesn’t drain well. It can clog roots and must be sterilized between uses.
SECONDARY NUTRIENTS
Calcium (Ca) and magnesium (Mg)
Sulphur or Sulfur
“S” is the symbol on the periodic table for Sulfur. It is an element that is vital for life. Crops that are wanting sulfur will have pale green young leaves and the plant will be stunted and spindly. Older leaves will remain green.
SYSTEMIC
Used in reference to a disease within the plant tissue, not initiated from the external cells. Also refers to materials and compounds which are taken up or absorbed by the plant and designed to fight disease
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- V -
VERMICULITE
Mica processed and expanded by heat. Vermiculite is a good soil amendment and medium for rooting cuttings. Holds more water than perlite and has natural “wicking” property that can draw water and nutrients in passive systems.
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- W -
WETTING AGENT
compound the reduces the droplet size and lowers the surface tension of the water, making it wetter. Liquid concentrate dish soap is a good wetting agent if it is biodegradable
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
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- Z -
ZINC
Noted by a “Zn” on the periodic table. Zinc is essential to the growth of all plants. Leaf tissue between the veins is lighter in color; yellowed and papery in appearance in plants deficient in zinc.
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