Terminology - Hydroponics language & vocabulary
There are a large number of terms in hydroponics that many indoor gardeners may not be familiar. Here are all the major terms that are used in hydroponics so that you can better understand what they mean and how they apply to your indoor gardening. This page will be updated periodically to keep track with new terms in this ever-expanding industry.
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Alternating Current (AC):
The type of electrical current found in most buildings and homes. AC means that the electrical current reverses directions at regular intervals.
Heavy clay. Unsuitable for hydroponics and container gardening.
Supplying plants, flowers and roots with air or oxygen.
The act of growing plants by suspending their roots in a mist. With this method, no medium is needed although generally only small plants are grown in this fashion.
A term for certain rocks, including gravel and lava rocks that are roughly the same size. It is used as inert material for hydroponics.
The term for the pH in nutrients that ranks at “7” or above.
Also called “general purpose fertilizer”, this is a balanced blend of N-P-K. An all-purpose fertilizer used by most non-hydroponic gardeners for the vegetative growth stage of their plants. The product “Miracle-Gro” is an example of an all-purpose fertilizer. This type of fertilizer is not recommended for hydroponics.
This measures the strength of an electrical current. For example, a 20 amp circuit describes the strength of the electrical current it can handle.
A term for plants whose life cycle lasts one year or less. Tomatoes and marigolds are examples of annual plants.
The luminous discharge of electricity between two electrodes.
The container for luminous gases. It also houses the arc.
The classification of plant hormones. The auxins are responsible for the foliage and elongation of roots.
Single cell organisms with no chlorophyll.
An insect that eats other insects which attack your plants. A ladybug is a beneficial insect.
The ability to decompose through natural bacterial processes. Items made of organic materials are biodegradable.
A cleansing solution, you can use one part laundry bleach and ten parts water as a fungicide.
A term for seeds that have bloomed prematurely, usually due to heat or other environmental factors.
A short or dwarf plant.
The electrical circuit box distinguished by on/off switches.
While stomata “breathe” CO2, the roots “breathe” oxygen.
The withering of the flower buds
This is the ability of a substance to resist fluctuations in their pH balance. In hydroponics, maintaining correct pH balance is critical.
Used to describe the outer shell of garlic or clove or the outer shell or jacket that protects the arc tube of an HID lamp.
Also known as the seed pod, it contains the female ovule and two pistils.
Carbon Dioxide (CO2):
An airborne gas necessary for plant life.
The cellulose, starches and sugars in plants are carbohydrates. It is a neutral compound of carbon, hydrogen and oxygen.
The capability of being destroyed by chemicals.
This is the basic unit of both plants and animals. A cell contains the nucleus, chloroplasts and membrane.
This is a complex carbohydrate that causes the plant to stiffen. A tough stem will contain cellulose.
Cubic Feet per Minute
A chemical that purifies water.
Combines nutrients in a atomic ring for easy absorption by the plants
A substance that contains chlorophyll
The inadequate formation of chlorophyll in a plant. It is noted by the yellowing leaves which denote illness. Leading causes of Chlorosis are an imbalance of pH or deficiency of iron.
The route travelled by electricity.
Soil that is created from very tiny mineral and organic particles. Clay is generally not suitable for container gardening.
The overall average environmental condition where plants grow, either indoors or outdoors.
This is the entire range of colors emitted by a source of light.
This is a color that is added to fertilizers so that horticulturists know that a fertilizer is in the solution.
This generally refers to soil that has been compacted. The more compacted the soil, the lesser the aeration and penetration of the roots.
This is adding garlic, marigolds or similar plants to the garden in order to discourage insects.
This is a mixture of decayed organic matter that is high in nutrient content. It must be at least a year old and when used, adds nitrogen to the soil.
In hydroponic ballast, this is the transformer which is also called the core.
The first leaves to appear on the plant, sometimes called “seed” leaves.
The pollination of two plants with different ancestry.
The width time length time height is the measurement of cubic feet.
A tip of a plant cut for asexual propagation.
This is a fungal disease that strikes seedlings and cuttings which causes them to rot at the base. Overwatering is the main culprit of damping-off.
Direct Current (DC):
Electrical current that flows in a single direction. Car batteries are examples of direct current.
To exhaust the supply of nutrients or to make infertile.
To dry up.
A cleanser made from liquid soap. This is used in gardening as a pesticide.
Having both male and female flowers
The outer part of the HID bulb on the opposite side of the threads and neck.
The brackets that support the arc tube within the outer envelope.
The process of removing excess water from the garden. Bad drainage means that the water stands still and stagnates.
The lines around the plant under the outermost blanch tips. The roots will seldom grow past the drip line.
A system used in hydroponics that includes a hose with small emitters of water that drip out the nutrients one at a time.
This is a white, cold substance formed when CO2 is cooled and compressed. Dry ice when heated will change into its gaseous state. Dry ice is used primarily in smaller gardens.
The drain hole which is often filled with rocks.
This is a conductor that is used to establish the electrical arc or contact with a non-metallic part of the circuit.
To grow in length.
The outer protective bulb, shell or jacket of the lamp.
This is the point when the sun crosses the equator which happens twice a year. At that point, daytime is exactly 12 hours long.
An electrical cord for devices too far from the power source.
The pistillate, ovule or seed producing part of the plant.
When too much fertilizer is used, the tips of the leaves curl and turn brown.
The electric fittings that hold the electrical components.
A shallow container, usually three inches deep that has good drainage and is used to start cuttings or seedlings.
The most reflective white paint available.
A electrical lamp tube that is coated with fluorescent materials. It is low in heat and power consumption, generally used to grow root cuttings.
The leaves or green part of the plant.
A misting fertilizer solution that is absorbed by the foliage.
This is fused in glass particles. A fritted trace element (FTE) is durable and does not leach out very easily.
A substance that destroys or inhibits the growth of fungus
A substance that prevents fungus from growing
A plant without chlorophyll which often attacks green plants. Bacteria, mildew, mold, mushrooms and rust are types of fungus.
The safety device found in electrical appliances which melts when too much electricity is passed through, thus protecting the electronics of the device itself.
The box that contains the fuses which controls electrical circuits.
Gallons Per Minute
General Purpose Fertilizer:
See All-Purpose Fertilizer
The part of the chromosome that influences the development of the plant itself. The genes are inherited properties of sexual propagation.
The totality of genes that are inherited from parent plants. The genetic make-up of a plant is the most important factor in its vigor, potency and vitality.
The binary compound of halogen or halogens that contain electro-positive elements.
Astatine, bromine, chlorine, fluorine or iodine that exists in a free state or the halogens arc found in the arc tube of a halide lamp.
A single plant with both male and female properties.
This is an electrical unit that cycles roughly once per second. For example, a home with a 60 hertz AC will cycle 60 times per second.
High Intensity Discharge
This is a sticky, honey-like substance that is secreted onto foliage by mealy bugs, scale and aphids.
The reflective cover of HID hydroponic lamps.
This is an abbreviation on many HID bulbs which indicates that they can burn in the horizontal position.
A chemical substance that controls the development and growth of a plant.
The water outlet which contains the on/off valve.
The ratio of the true amount of moisture in the air to the greatest amount that the air can hold at that temperature.
A dark, fertile organic part of the soil formed by decomposed plant or animal matter.
The offspring of different plants of different breeds, genetic make-up or variety.
Used to change pH balance, it is an instantly soluble lime.
The lightest of all gasses, hydrogen combines with oxygen to form water.
The instrument that measures the relative humidity in the air.
Also known as “True Breed”, this is the offspring of plants of the same breed or ancestry.
A chemically non-reactive material or medium used in hydroponics. It does not interfere with nutrient solutions.
This is the magnitude of light energy per unit. Generally speaking, it means the further away from the light source, the less intense the light overall.
The protective outer bulb or shell of a lamp
Jiffy 7 Pellet:
This is compressed peat moss wrapped in an expandable casing of plastic. Adding water will expand a Jiffy 7 Pellet into a small pot for seeds of cuttings.
The measurement of electricity that is used each hour. For example, a 1000-watt HID lamp uses a single kilowatt per hour.
To wash out soluble components of soil through heavy watering. This is used in hydroponics to flush out excesses of fertilizer salts.
This is the malformation of a leaf caused by over fertilization, over watering, lack of magnesium or damage by insects, negative tropism or fungal infection.
This is a small, immature leaf
An abnormally tall plant usually with sparse foliage, a condition generally caused by the lack of light.
The total amount of growth stages which a plant experiences in its natural lifetime from seed, seedling, vegetative and floral.
This device moves the light source back and forth across the ceiling in the grow room for more even distribution of the light.
Used to raise and stabilize pH in soil, often in the form of hydrated lime or dolomite.
A chemically sensitive paper used for testing pH balance.
The organic soil mixture consisting of silt, sand and crumbing clay.
The measurement of the output of light. For example, a single lumen is equivalent to the amount of light emitted by a single candle that strikes one square foot of surface located one foot away.
A single or all of the primary nutrients known as N-P-K or the secondary nutrients known as calcium and magnesium.
The average throughout the lifespan. For example, HID’s are rated in “mean” lumens.
Also called “Trace Elements:, micronutrients include the following substances;
A one-thousandth of a meter.
A device that measures the moisture content of the soil.
Producing only a single color, such as LP sodium lamps are monochromatic.
This is a protective covering of organic compost materials such as old leaves and so forth. Mulch is not needed indoors as it produces too much moisture.
The scale used to measure electromagnet waves lengths of light. The color and light spectrums are measured in nanometers.
The localized death of a part of a plant.
The glass end of the HID bulb which is attached to the threads.
The food of the plant, such as N-P-K along with secondary and trace elements
Ohm’s Power Law:
Volts time Amperes equals Watts. This law expresses the strength of an electric current.
This is substances created from matter that was formally living.
To load to excess. For example, a 20 amp circuit that draws 17 amps is overloaded.
The egg of a plant which is found within the calyx. It contains all the female genes and when fertilized will grow into a seed.
A gas in the soil necessary to sustain life.
An organism that lives off another host organism, such as fungus.
This is partially decomposed vegetation, such as moss, with a slow rate of decay due to extreme moisture and cold conditions.
A plant that completes its life cycle over a number of years, such as a tree or shrub.
A scale the measures the acid or alkaline balance for a growing medium. For hydroponics, a pH balance of 5 to 6.5 is generally ideal.
This is an electronic instrument that measures the pH balance in soil or water.
The internal bulb coating that diffuses the light and is responsible for the various outputs of color.
The relationship between the amount of light and dark in a 24 hour period.
The construction of chemical compounds or carbohydrates from light energy, water and CO2.
The movement of the plant towards the light source.
The substance that absorbs light and produces the same color as the pigment.
Microspores that contain the male genes of a plant, usually a fine, dust-type particle
A dry calyx which contains a mature seed
A plant that is bound or inhibited from normal growth by a container. A pot will contain the roots of the plant.
This is an overflow of the amount of electricity.
Either sexual propagation which uses seeds from different male and female flowers or asexual propagation which uses the cuttings of plants.
To alter the shape of the plant through cutting
A plyvinyl chroide pipe that is commonly used, easy to reshape and readily available for gardens.
This is a natural insecticide created from the blossoms of Chrysanthemums.
To restore to a state of youthfulness. A plant that has completed its life cycle may be stimulated by a new photoperiod to rejuvenate or produce new vegetative growth.
See Pot Bound
Crystalline compound that will result from improper pH balance or a fatal buildup of fertilizer. The salt will burn plants and prevent them from absorbing any nutrients.
They are calcium and magnesium
When electrical wires cross and form a additional circuit which can blow fuses.
The threaded holder for a bulb
The ability to dissolve in water
The seed-like offspring of fungus
A small, new growth of stems or leaves or a recently germinated seed.
The length in feet times the width equals square feet of the space.
The male, pollen producing part of the plant.
A complex carbohydrate, the start of the plant stores the food.
To remove the dirt, bacteria and germs. Using a water solution with 10% bleach can effectively sterilize hydroponic equipment.
The pulsating or flashing of light.
The exertion of a plant. A stressed plant will not grow as well as a plant without stress.
A small mouth-like opening or pore on the underside of leaves. The stomata are responsible for many of the life functions of the plant.
The food of a plant
A common name for a fertilizer rich in phosphorus that produces the growth and formation of flowers.
The production of a substance that units the energy of light, chemicals and other elements.
The reservoir that acts as a drain for hydroponic nutrient solutions.
The primary root that grows from the seed. Lateral roots branch off from the tap or main root.
Used to seal off pipe joints and the life, Teflon tape is very strong and durable.
Warm water, usually around 70F to 80F that is used to water plants.
The bud which grows at the end of the stem
To cull out weak or slow growing seedlings
The amount of time pesticides remain viable or active
A device that transformed electrical current from one voltage to another voltage.
To give off water vapor and other by products though the stomata.
A frame of PCV, lattice or small boards that supports the plants.
A hard, heavy metal with a high melting point that conducts electricity. Tungsten is used as filaments for many halogen lamps.
Very short wavelengths of light, it lies outside the visible spectrum.
The strain or phenotype
A opening, such as a door or window that allows in fresh air.
The circulation of fresh air, vital for healthy indoor gardens.
Up and down, it is perpendicular to horizontal which is side to side.
The compound that reduces the size of droplets and the surface tension of water, which makes it “wetter”. For example, soap is a wetting agent.
Used in a passive hydroponic system, the wick is suspended in the nutrient solution and passes the nutrients to the plant.