Glossary

Alternating Current (AC): An electric current that reverses its direction at regular occurring intervals. Homes have AC.

Acid: An acid or sour substance has a pH below 7. Aeration: Supplying soil and roots with air or oxygen.

Aeroponics: Growing plants by misting roots suspended in air.

Alkaline: Refers to a substance with high pH; Any pH over 7 is considered alkaline.

All-Purpose (General-Purpose) Fertilizer: A balanced blend of N-P-K; All purpose fertilizer is used by most growers.

Amendment: Fortifying soil by adding organic or mineral substances in order to improve texture, nutrient content or biological activity.

Ampere (Amp): The unit used to measure the strength of an electric current.

Annual: A plant that normally completes it entire life cycle in one year or less. Tomatoes are examples of annual plants.

Arc: Luminous discharge of electricity (light) between two electrodes.

Arc Tube: A quartz container for luminous gases also houses the arc in HID lights.

Auxin: Classification of plant hormones; Auxins are responsible for foliage and root elongation.

Bacteria: Very small, one-celled organisms.

Beneficial Insect: A good insect that eats bad flower and vegetable munching insects.

Biodegradable: Able to decompose or break down through natural bacterial or fungal action, substances made of organic matter are biodegradable.

Bolt: Term used to describe a plant that has gone to seed prematurely.

Bonsai: A very short or dwarfed plant.

Breaker Box: Electrical circuit box having on/off switches rather than fuses.

Breathe: Roots draw in or breathe oxygen, stomata draw in or breathe carbon dioxide.

Bud Blight: A withering condition that attacks flower buds.

Buffering: The ability of a substance to reduce shock and cushion against pH fluctuations.

Bulb: The outer glass envelope or jacket that protects the arc tube of an HID lamp.

Bulbs: Common are tulips and daffodils planted in the fall for spring blooms, or forced indoors for winter blooms.

Calyx: The pod harboring female ovule and two protruding pistils, seed pod.

Carbon Dioxide: (CO2) A colorless, odorless, tasteless gas in the air necessary for plant life and biomass accumulation.

Carbohydrate: Neutral compound of carbon, hydrogen and oxygen. Sugar, starch and cellulose are carbohydrates.

Caustic: Capable of destroying, killing or eating away by chemical activity.

Cell: The base structural unit that plants are made of; cells contain a nucleus, that houses it's DNA.

Cellulose: A complex carbohydrate that stiffens a plants tissue.

CFM: Cubic feet per minute.

Chelate: Combining nutrients in an atomic ring that is easy for plants to absorb.

Chlorine: Chemical used to purify water.

Chloroplast: Containing chlorophyll.

Chlorosis: The condition of a sick plant with yellowing leaves due to inadequate formation of chlorophyll. Chlorosis is caused by nutrient deficiency, usually iron or imbalanced pH.

Clay: Soil made of very fine organic mineral particles. Clay is not suitable for container gardening.

Climate: The average condition of the weather in a garden room or outdoors.

Color Spectrum: The band of colors (measured in nm) emitted by a light source.

Color Temperature: The relative whiteness of a piece of tungsten steel heated to that temperature in degrees kelvin.

Color Tracer: A coloring agent added to many commercial fertilizers, so the horticulturist knows there is fertilizer in the solution.

Compaction: Soil condition that results from tightly packing soil; compacted soil allows for only marginal aeration and root penetration.

Companion Planting: Planting garlic, marigolds, etc., along with other plants to discourage insect infestation.

Compost: A mixture of decayed organic matter.

Core: The transformer in the ballast is referred to as the core in HID lighting systems. Corms, Rhizomes and Tubers: Dormant stems planted in the fall for spring blooms, or forced indoors for winter blooms. Common varieties are dahlias and irises.

Cotyledon: Energy storage components of a seed that feed the plant before the emergence of its first true leaves.

Cross-Pollinate: Pollinating two plants having different ancestry. Cubic Foot: Volume measurement in feet: L" x W" x H" ÷ 1728" = Cu. Ft. Cutting: (1) Growing tip cut from a parent plant for asexual propagation (2) Clone.

Damping-Off: Disease that attacks young seedlings and cuttings causing stem to rot at base.

Direct Current (DC): An electric current that flows in only one direction.

Deplete: Exhaust soil of nutrients, making it infertile.

Desiccate: Cause to dry up. Insecticidal soap desiccates its victims.

Dioecious: Having distinct male and female organs on different plants within the same species.

Dome: The part of the HID outer bulb opposite the neck and threads.

Dome Support: The spring like brackets that mount the arc tube within the outer envelope.

Drainage: Way to empty soil of excess water: with good drainage, water passes through soil evenly.

Drip Line: A line around a plant directly under its outermost branch tips: Roots seldom grow beyond the drip line.

Drip System: A very efficient watering system that employs a main hose with small water emitters.

Dry Ice: A cold, white substance formed when carbon dioxide is compressed and cooled; dry ice changes into CO2 gas at room temperature.

Electrode: A conductor used to establish electrical arc or contact with non-metallic part of circuit.

Elongate: Growth in length.

Envelope: Outer protective bulb or jacket of a lamp.

Equinox: The point at which the sun crosses the equator and day and night are each 12 hours long; the equinox occurs twice a year, in spring and fall.

Feed: Deliver nutrient to the plant via roots or foliage. Female: Pistillate, ovule, seed producing.

Ferreting: To fertilize and irrigate at the same time.

Fertilizer Burn: Over fertilization: first leaf tips burn (turn brown) then the leaves curl.

Flat: Shallow (three inch) deep container, often 18 by 24 or 10 by 20 inches with good drainage, used to start seedlings or cuttings.

Fluorescent Lamp: Electric lamp using a tube filled with fluorescent material, which has a low heat output.

Foliage: The leaves or more generally, the green part of a plant.

Foliar Feeding: Misting fertilizer solution which is absorbed by the foliage. Best to do when first turning on your lights.

Foot-Candle: The unit is defined as the amount of illumination that the surface of an imaginary 1-foot radius sphere would be receiving if there were a uniform point source of one candle in the exact center of the sphere. The foot-candle is equal to one lumen per square foot. Foot-candle is a derived unit of illuminance from Lux. One foot-candle is equal to 10.76 lux.

Fungistat: A product that inhibits fungus keeping it in check.

Fungus: A lower plant lacking chlorophyll which may attack green plants; mold, rust, mildew.

Fuse: Electrical safety device consisting of a metal that melts and interrupts the circuit when circuit is overloaded.

Fuse Box: A box containing fuses that control electric circuits.

GPM: Gallons per minute.

Gene: Part of a chromosome that influences the development of plant; genes are inherited through sexual propagation.

Genetic Make Up: The set of genes inherited from parent plants.

Halide: Binary compound of a (halogens) with an electropositive elements.

Hermaphrodite: One plant having both male and female organs; the breeding of hermaphrodites is hard to control.

Hertz (hz): A unit of frequency that cycles one time each second: a home with 60 Hertz AC current cycles 60 times per second.

HID: High Intensity Discharge. Honey Dew: A sticky, honey like substance secreted into foliage by aphids, scale and mealy bugs.

Hood: Reflective cover of a HID lamp.

HOR: The abbreviation stamped on some HID bulbs meaning they must be burned in a horizontal position.

Horizontal: Parallel to the horizon, ground or floor.

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

Humidity (relative): Ratio between the amount of moisture in the air and the greatest amount of moisture the air could hold at the same temperature.

Humus: Dark, fertile, partially decomposed plant or animal matter; humus forms the organic portion of the soil.

Hybrid: An offspring from two plants of different breeds, variety or genetic make up.

Hydrated Lime: Instantly soluble lime, used to raise pH or sweeten soil.

Hydrogen: Light or colorless, odorless gas; hydrogen combines with oxygen to form water.

Hygrometer: Instrument for measuring relative humidity in the atmosphere.

Inbred: (True Breed) Offspring of plants of the same breed or ancestry. Inert: Chemically non-reactive; inert growing mediums make it easy to control the chemistry of the nutrient solution.

Intensity: The magnitude of the light energy per unit; intensity diminishes the farther away from the source.

Jacket: Protective outer bulb or envelope of lamp. Kilowatt

Hour: Measure of electricity used per hour; a 1000- watt HID uses one kilowatt in one hour.

Lacewing: Beneficial insects that preys on aphids.

Leach: Dissolve or wash out soluble components of soil by heavy watering.

Leaf Curl: Leaf malformation due to over-watering, over fertilization, lack of magnesium, insect or fungus damage or negative tropism.

Leaflet: Small immature leaf.

Leaves: The external part of a plant attached to branches and stems for the purpose of taking in light from the sun's energy. They do this with chloroplasts in the cells which contain chlorophyll.

Leggy: Abnormally tall internode space, with sparse foliage. Leggyness of a plant is usually caused by lack of blue light or CO2. Too much nitrogen can also cause this.

Life Cycle: A series of growth stages through which a plant must pass in Its natural lifetime; the stages for an annual plant are seed, seedling, vegetative and floral.

Light Mover: A device that moves a lamp back and forth or in a circle across the ceiling of a garden room to provide more even distribution of light.

Lime: Used in the form of dolomite or hydrated lime to raise and stabilize soil pH.

Litmus Paper: Chemically sensitive paper used for testing pH.

Loam: Organic soil mixture of crumbly clay, silt and sand.

Lumen: Measurement of light output: one lumen is equal to the intensity of light emitted by one candle that falls on one square foot of surface located one foot away from one candle.

Macro Nutrient: One or all of the primary nutrients N-P-K or the secondary nutrients magnesium and calcium.

Mean: Average throughout life; HID's are rated in mean lumens.

Meristem: Tip of plants growth.

Micro Nutrient: Also referred to as trace elements, including S, Fe, Mn, B, Mo, Zn, and Cu.

Millimeter: Thousandth of a meter approximately .04 inch.

Moisture Meter: An electronic device that measures the exact moisture content of soil at any given point.

Monochromatic: Producing only one color; LP sodium lamps are monochromatic.

Mulch: A protective covering of organic compost, leaves, etc.; indoors, mulch keeps soil too moist and possible fungus could result.

Nanometer: .000000001 Meter, nm is used as a scale to measure wave lengths of light; color and light spectrums are expressed in nanometers (nm).

Necrosis: Localized death of a plant part.

Neck: Tubular glass end of the HID bulb, attached to the threads.

Nutrient: Plant food, essential elements N-P-K, secondary and trace elements fundamental to plant life.

Ohm's Power Law: A law that expresses the strength of an electric current; volts times amperes equals watts.

Organic: Made of, or derived from or related to living organisms. In agriculture organic means "natural". In chemistry organic means "a molecule or substance that contains carbon".

Ovule: A plant's egg found within the calyx, it contains all the female genes; when fertilized, an ovule will grow into a seed.

Oxygen: Tasteless, colorless element, necessary in soil to sustain plant life as well as animal life.

Parasite: Organism that lives on or in another host organism; fungus is a parasite.

Peat: Partially decomposed vegetation (usually moss) with slow decay due to extreme moisture and cold.

Perennial: A plant, such as a tree or shrub, which completes its life cycle over several years.

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 5.5 to 6.8 pH.

pH Tester: Electronic instrument or chemical used to find where soil or water is on the pH scale.

Photometrics: The study of light, especially color.

Phosphor Coating: Internal bulb coating that diffuses light and is responsible for variations in color outputs.

Photoperiod: The relationship between the length of light and dark in a 24 hour period.

Photosynthesis: The building of chemical compounds (carbohydrates) from light energy, water and carbon dioxide.

Phototropism: The specific movement of a plant part towards a light source.

Pigment: The substance in paint or anything that absorbs light, producing (reflecting) the same color.

Pollen: Fine, dust like microspores containing male genes.

Power Surge: Interruption or change in intensity of electricity.

Primary Nutrients: N-P-K

Propagate: (1) Sexual: Produce a seed by breeding different male and female flowers (2) Asexual: To produce a plant by taking cuttings.

Prune: Alter the shape and growth pattern of a plant by cutting stems and shoots.

PVC Pipe: Plastic (polyvinyl chloride) pipe that is easy to work with, readily available and used to pipe water into a garden room.

Pyrethrum: Natural insecticide made from the blossoms of various chrysanthemums.

Root Bound: Roots stifled or inhibited from normal growth, by the confines of a container.

Roots: Their purpose is to anchor a plant and provide a means in which to feed and hydrate a plant.

Rejuvenate: Restore youth; a mature plant, having completed its life cycle (flowering), may be stimulated by a new 18 hour photo period, to rejuvenate or produce new vegetative growth.

Salt: Crystalline compound that results from improper pH or toxic buildup of fertilizer. Salt will burn plants, preventing them from absorbing nutrients.

Secondary Nutrients: Calcium (ca) and Magnesium (mg). Seed Pod: A dry calyx containing a mature or maturing seed.

Short Circuit: Condition that results when wires cross and form a circuit. A short circuit will blow fuses.

Socket: Threaded, wired receptacle for a bulb.

Soluble: Able to be dissolved in water.

Spore: Seed like offspring of a fungus. Sprout: (1) A recently germinated seed (2) Small new growth of a leaf or stem. Square Feet (Sq Ft): Length (in feet) times width equals square feet.

Stamen: Male, pollen-producing.

Starch: Complex carbohydrate; starch is manufactured and stored in food.

Sterilize: Make sterile (super clean) by removing dirt, germs and bacteria.

Stroboscopic Effect: A quick pulsating or flashing of a lamp.

Stress: A physical or chemical factor that causes extra exertion by plants; a stressed plant will not grow as well as a non stressed plant.

Stomata: Small mouth like or nose like openings (pores) on leaf underside, responsible for transpiration and many other life functions; the millions of stomata, must be kept very clean to function properly.

Sugar: Food product of plant. Carbohydrates that contain hydrocarbon chain.

Synthesis: Production of a substance, such as chlorophyll, by uniting light energy and elements or chemical compounds. Tap

Root: The main or primary root that grows from the seed; lateral roots will branch off the tap root. Tepid: Warm 70 to 80 degrees F (21 to 27 degrees C); always use tepid water around plants to facilitate chemical processes and ease shock.

Terminal Bud: Bud at the growing end of the main stem.

Thin: Cull or weed out weak, slow growing seedlings.

Transformer: A device in the ballast that transforms electric power from one voltage to another.

Transpire: Give off water vapor and bi-products via stomata and carbon dioxide intake at the leaves.

Trellis: Frame or netting (lattice) that trains or supports plants.

Tungsten: A heavy, hard metal with high melting point which conducts electricity well; tungsten is used for a filament in tungsten halogen and incandescent lamps.

Ultraviolet: Light with very short wave lengths, out of the visible spectrum, past the blue-violet.

Variety: Strain, phenotype.

Vent: Opening such as a window or door that allows the circulation of fresh air.

Ventilation: Circulation of fresh air, fundamental to a healthy indoor garden, an exhaust fan creates excellent ventilation.

Vertical: Up and down perpendicular to the horizontal.

Wetting Agent: Compound that reduces the droplet size and lowers the surface tension of the water, making it wetter.

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.