Acidic - Acidic soil has a low pH level under 6.5.
Aeration - A hydroponics system that suspends plants' roots in the air and supplies the best air and oxygen.
Alkaline - Alkaline soil with a high pH level over 7.
Color Spectrum - the rainbow band of colors (ranging from red to indigo-blue) emitted by a light source.
Compost - A miss-mash of decayed organic matter, high in nutrients and ideal as a natural plant fertilizer.
Drip System - A hydroponic system that drips water from emitters onto plants.
Fluorescent Lights - used in hydroponic growing to sprout seedlings and to initiate rooting. Fluorescent lights have a minimal effect compared to HID lights, but they are more energy efficient.
Ebb and Flow - a hydroponic system that temporarily floods plants with nutrient solution then drains it.
Fungicide - A product that destroys or inhibits fungus.
Fungus - A plant that totally lacks chlorophyll such as mold, rust, mildew, mushrooms and bacteria. Fungi attacks and kills green plants.
Grow Medium - supports the plant roots and absorbs nutrients.
HID Lights - or high intensity discharge lights are the most effective artificial light source available to hydroponic plants. HID lights are most comparable to sunlight.
Humidity - the amount of moisture in the air.
Hydroponics - a method of growing plants without soil.
Leach - to remove substances by percolating liquid, through a grow medium in the case of hydroponics.
L.E.C.A - or Light Expanded Clay Aggregate - is a grow medium formed from natural clay baked into pellets.
Light Mover - like an oscillating fan, this device moves a lamp across the ceiling of a garden room in order to distribute light evenly.
Litmus Paper - reads pH levels when dipped in water or nutrient solution.
Lumen - the measurement of a light's output.
Nutrient Film Technique (or NFT) - grows plants under a constant flow of nutrients and water.
Nutrient - essential elements for plant life include nitrogen, phosphorous and potassium (N-P-K) as well as trace elements (which are specific to the plant).
Organic - matter that comes from living organisms.
pH - a measurement of the acid to alkaline balance of a growing medium. pH is measured on a scale from 1.0 to 14.0. A pH of 7.0 is totally neutral.
Perlite - is mined volcanic glass heated to extreme temperatures and used as a grow medium. Perlite is often combined with vermiculite.
Photosynthesis - the process by which plants convert light energy (carbon dioxide and water) into chemical energy or carbohydrates (sugar and starch) and the release of oxygen. Photosynthesis occurs when light affects the chlorophyll of green plants.
Primary Nutrients - N (nitrogen), P (phosphorus, K (potassium) - often seen as N-P-K.
Rockwool - a grow medium made from basalt rock and chalk and baked.
Sugar - food source of a plant.
Trellis - a wooden frame or lattice that fixes plants in rows or supports plants.
Ultraviolet - light emitted in extremely short wave lengths, so blue that humans can't see it.
Ventilation - the process of expelling stale air and circulating fresh air. Hydroponics growers use exhaust fans for ventilation.
Vermiculite - a mined material of golden flecks that can soak up to 3 to 4 times its weight in water. Vermiculite is often combined with perlite as a grow medium.