GLOSSARY


AERATION

  • Supplying soil and roots with air or oxygen. Geolite is an example of a medium with excellent aeration. In some hydroponic systems, a nutrient solution is aerated by the output of an aquarium pump.

AEROPONICS

  • A system in which the roots of a plant are consistently or intermittently misted with fine droplets of nutrient solution.

ACIDIC

  • Refers to medium or nutrient solution with a low pH; an acidic solution has a pH below 7.

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.

BALLAST

  • An auxiliary piece of equipment designed to start and to properly control the flow of power to gas discharge light sources such as fluorescent and high intensity discharge lamps. In metal halide systems, it is composed of the transformer, capacitor and connecting wiring; sodium systems require an ignitor in addition to the transformer and capacitor.

BORON (B)

  • The function of this micronutrient is not well understood, but it is suspected that it might aid carbohydrate transport.

CALCIUM (Ca)

  • Calcium is vital in all parts of plants to promote the translocation of carbohydrates, healthy cell wall structure, strong stems, membrane maintenance and root structure development. Calcium is a macronutrient.

CANDELA (CD)

  • A unit of luminous intensity in a given direction, equal to one lumen per steradian.

CANDLEPOWER (CP)

  • The luminous intensity of a light source, as expressed in candelas.

CANDLEPOWER DISTRIBUTION CURVE

  • A curve that represents the varying distribution of luminous intensity of a lamp or luminaire.

CAPACITOR

  • An electronic device that can store electrical charge. The capacitor is one of the main components of an HID lighting ballast. Because they can store a very strong electrical charge, capacitors can be very dangerous to someone who is unaware of this fact and opens a ballast in order to examine or repair it. If one does not know how to safely discharge the stored electricity, one should allow a trained technician to do any ballast repairs.

CARBON DIOXIDE (CO2)

  • A colorless, odorless, tasteless gas in the air necessary for plant life. Occurs naturally in the atmosphere at .03%.

CHLORINE (Cl)

  • This micronutrient is essential for photosynthesis, where it acts as an enzyme activator during the production of oxygen from water.

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 nitrogen; nutrient deficiencies are themselves often caused by a pH that is out of the acceptable range.

CLONE

  • A plant produced through asexual reproduction including, but not limited to, cuttings, layering and tissue culture.

COLOR TEMPERATURE or KELVIN TEMPERATURE

  • The unit of measurement to express the color (spectrum) of light emitted by a lamp; the absolute temperature of a blackbody radiator having a chromaticity equal to that of the light source (see correlated color temperature).

CONDITIONING

  • To soak new Rockwool in an acidic solution to lower the pH from 8.0 to 5.5.

COPPER (Cu)

  • This micronutrient is an internal catalyst and acts as an electron carrier; it is also believed to play a role in nitrogen fixation.

CORRELATED COLOR TEMPERATURE (CCT)

  • A specification of the color appearance of a light source, relating its color to that of a blackbody radiator, as measured in Kelvins (K). CCT is a general measure of a lamp's "coolness" or "warmness."

DAMPING-OFF FUNGUS

  • Disease that attacks young seedlings and cuttings, causing stems to rot at the base; overwatering is the main cause of damping-off.

DRIP IRRIGATION

  • 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.

EBB AND FLOW

  • A hydroponic system in which the medium, usually aggregate pebbles, is periodically flooded with nutrient solution and then drained again, feeding and aerating the medium and root system.

FLUORESCENT LAMP

  • A discharge lamp in which a phosphor coating transforms ultraviolet energy into visible light. Fluorescent lamps are good for starting seedlings and rooting cuttings, but do not have enough intensity to sustain aggressive growth in plants in the later stages of life, and are not efficient enough in their conversion of electrical power to lumens of light output.

FOLIAR FEEDING

  • Misting plants with fertilizer solution, which is absorbed by the foliage.

FOOTCANDLE

  • A standard measurement of light intensity, representing the amount of illuminance on a surface one foot square on which there is a uniformly distributed flux of one lumen. More simply, one footcandle of illuminance is equal to the light emitted by one candle at a distance of one foot.

FUNGICIDE

  • A product that destroys or inhibits fungus.

FREQUENCY

  • The number of waves or cycles of electromagnetic radiation per second, usually measured in Hertz (Hz).

GERMINATION

  • The process of causing the initiation and development of a plant from seed.

HIGH-PRESSURE SODIUM LAMP

  • High-pressure sodium lamps operate by igniting sodium, mercury and xenon gases within a sealed ceramic arc tube. Sodium lamps emit light energy in the yellow/red/orange regions of the spectrum; the red spectrum stimulates flowering and fruit production. Many indoor gardeners switch to sodium lamps when it is time to induce flowering or fruiting of their plants.

HORMONE

  • Chemical substance that controls the growth and development of a plant. Root-inducing hormones help cuttings root.

HYDRATED LIME

  • Instantly soluble lime, used to raise or lower pH.

HYGROMETER

  • An instrument for measuring relative humidity in the atmosphere.

ILLUMINANCE

  • The density of incident luminous flux on a surface; illuminance is the standard metric for lighting levels, and is measured in lux (lx) or footcandles (fc).

IRON (Fe)

  • This micronutrient acts as a catalyst in the photosynthesis/respiration process, and is essential for the formation of sugars and starches. Iron also activates certain other enzymes.

KILOWATT (kW)

  • A unit of electric power usage equal to 1,000 watts.

KILOWATT HOUR (kWh)

  • A measurement of electric energy. A kilowatt hour is equal to 1,000 watts of power used over a period of one hour.

LAMP LUMEN DEPRECIATION (LLD)

  • The decrease over time of lamp lumen output, caused by bulb wall blackening, phosphor exhaustion, filament depreciation, and other factors.

LED

  • An LED lamp is a solid-state lamp that uses light-emitting diodes (LEDs) as the source of light. LED lamps offer long service life and high energy efficiency, but initial costs are higher than those of fluorescent and incandescent lamps. Chemical decomposition of LED chips reduces luminous flux over life cycle as with conventional lamps.

LUMEN

  • A measurement of light output; refers to the amount of light emitted by one candle that falls on one square foot of surface located at a distance of one foot from the candle.

MACRONUTRIENTS

  • The primary nutrients N-P-K or the secondary nutrients magnesium and calcium.

MANGANESE (Mn)

  • This micronutrient activates one or more enzymes in fatty acid synthesis; it also activates the enzymes responsible for DNA and RNA production. Closely associated with copper and zinc, manganese also participates directly in the photosynthetic creation of oxygen from water.

METAL HALIDE LAMP

  • A high-intensity-discharge lamp in which the light is produced by arcing electricity through a mixture of metal halides. The light produced by metal halide lamps is in the white-blue spectrum, which encourages vegetative growth and "bushiness" while discouraging upward growth. This is the bulb to use in the first, vegetative phase of plant growth.

MICRONUTRIENTS

  • Also referred to a TRACE ELEMENTS, including S, Fe, Mn, B, Mb, An and Cu.

MOLYBDENUM (Mo)

  • This micronutrient is essential for nitrogen fixation and nitrate reduction.

NECROSIS

  • The dying of plant tissue, usually the result of serious nutrient deficiency or pest attack.

NITROGEN (N)

  • Nitrogen is used in various forms to promote rapid vegetative growth, leaf, flower, fruit and seed development, and chlorophyll development; and to increase the protein content in all plants.

NFT (NUTRIENT FILM TECHNIQUE)

  • A hydroponic method in which nutrient is fed into grow tubes or trays in a thin film where the roots draw it up. This "nutrient film" allows the roots to have constant contact with the nutrient and the air layer above at the same time.

NUTRIENTS

  • The elements needed by plants for normal growth and health. The major nutrients (MACRONUTRIENTS) are nitrogen (N), phosphorus (P), and potassium (K), but there are numerous MICRONUTRIENTS (also called TRACE ELEMENTS) which also have integral roles in maintaining plant health. A good quality hydroponic nutrient formula will contain all of the major nutrients and micronutrients needed by the vast majority of plants.

NUTRIENT SOLUTION

  • The mixture of water and water-soluble nutrients which is provided to the plants for nourishment in a hydroponic system.

pH

  • A scale from 1 to 14 that measures the acid to alkaline balance of a growing medium (or any other substance). In general, plants grow best in a pH range of 6 to 6.8; 6.3 is considered ideal. If the pH is not within the acceptable range, nutrients may not be absorbed to maximum capacity.

PHOSPHORUS (P)

  • Phosphorus promotes and stimulates early growth and blooming and root growth. It hastens maturity and seed growth, and contributes to the general hardiness of plants. Phosphorus is a macronutrient.

POTASSIUM (K)

  • Potassium promotes disease resistance and good development of carbohydrates, starches and sugars, and it increases fruit production. Potassium is a macronutrient.

PERLITE

  • Sand or volcanic glass which has been expanded by heat; perlite holds water and nutrients on its many irregular surfaces.

PHOTOPERIOD

  • Day length; 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.

PROPAGATE

  • To produce seed by breeding different male and female flowers or to produce plantlets (also known as CLONES) by taking cuttings.

PYRETHRUM

  • Natural insecticide made from the blossoms of various chrysanthemums.

ROCKWOOL

  • Inert, soilless growing medium consisting of woven, thin strand-like fibers made from molten volcanic rock and limestone, which is heated to over 2900 degrees F, extruded, and formed into slabs, cubes and blocks.

VERMICULITE

  • Mica which has been processed and expanded by heat. Vermiculite has excellent water-retention qualities and is a good soil amendment and medium for rooting cuttings.

ZINC (Zn)

  • Like copper and manganese, zinc is linked to chlorophyll synthesis.

 

 

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