GROW: to increase by natural development, as any living organism or part by assimilation of nutriment; increase in size or substance.
Glossary of Horticultural Terms
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 annuals 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 plants 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: grow 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.
Fertigate: 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: 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.
I - J - K
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.
LeD: Light Emitting Diode
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 micro-spores 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: 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 by 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.
U - V - W
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.