Hydroponic Glossary

Hydroponic Glossary


  • Absorption – Substance uptake into plants. This can be liquids i.e Nutrients or gases such as oxygen.
  • Adsorption – When substances attach to a surface. Such as foliar sprays etc.
  • Adult – A plant capable of forming flowering tissues.
  • Antiseptics – Micro-organism deterring substance that reduce risk of infection when applied to plants.
  • Aeration – Supplying soil and roots with air or oxygen. Some hydroponic systems create an aerated nutrient solution with the use of an aquarium pump and air stones.
  • Aeroponic – Such as our Amazon system, roots are consistently or intermittently misted with nutrient solution. See also X-Stream Aeroponic Propagators.
  • Acid – Media or nutrient solution with low pH, below 7.
  • Alkaline – Media or nutrient solution with a high pH, over 7.


  • Bloom phase – The period of growth when plants flower.
  • Buffering – Reducing dramatic pH level variation in a solution.
  • Bloom / Blossom Booster – Nutrients that are high in phosphorus (P) which increases flower yield.
  • Burn – Leaf tips brown due to excess nutrients and salt. Causing the plants to burn.


  • Capillary action – The method in which fibres to soak up water.
  • Carbon Filters – Are used to scrub the air in a grow room of  VOC’s before it leaves the grow room. The absorbency of the carbon draws V.O.C’s in and traps them in its porous body.
  • Cell – Smallest living organism able to live independently.
  • Chelate  – Organic structure containing metal element preventing oxydation.
  • Chlorophyll  – A plants green pigment. Essential to photosynthesis as it captures the photon of light
  • Clay pellets  – Growing medium of small hard baked clay pellets. See Clay Pebbles.
  • Coco / Coir – Growing media created from the natural fiber of coconut husks. See Coco / Coir.
  • Combination Day Plants – A plant requiring exposure to short day conditions and long day conditions in a particular order to encourage flowering.
  • Contactor / Relay – Units with the purpose of controlling electrical surges so as to protect electrics from fusing. See Green Power Contactors.
  • Cutting – Asexual propagation of plants taken from the tip containing a meristem as either a terminal or auxillary bud.
  • Carbon Dioxide (CO2) – A colorless, odorless, tasteless gas in the air, essential for plant life. Occurs naturally in the atmosphere.
  • Chlorosis – Sick plant with yellowing leaves caused by a nutrient deficiency, usually iron or nitrogen.


  • Dilution – When nutrient solutions are made less concentrated by adding water.
  • DNA – A structure containing the characteristics of a living organism.
  • Drainage – Waste water that is removed from a system or re-circulated.
  • Dampening Off – Overwatering is the main cause of damping-off. This is a disease that effects seedlings and cuttings, causing stems to rot.
  • Drip Aeration – Watering method that utilises air pressure from an air pump to filter nutrient solution out of a ring of circular feeding ring.
  • Dripper System – Watering system using a main hose with small water drippers. Water is released from the drippers, one drop at a time. See Dripper Systems.


  • EC – Electric conductivity. Used to measure ion concentration (concentration of salt) in water. See EC Meters.
  • Enzyme – Protein molecules of a very specific function. A catalyst for biochemical reactions.
  • Ebb and Flood – A system where media is periodically flooded with nutrient solution and then drained, feeding and aerating the media and roots. See Ebb & Flood Systems.


  • Fans and Air movement – Fans are a vital tool in maintaining a desirable environment for plants. They can be used to maintain negative pressure in a grow room.
  • Fertigation – Nutrient, or other water-soluble product application through an irrigation system.
  • Flood and Drain – A system where media is periodically flooded with nutrient solution and then drained, feeding and aerating the media and roots. See Flood & Drain Systems.
  • Floral Phase – The period when plants is put on floral structures.
  • Fructification – When a plant forms fruits.
  • Foliar Feeding – Spraying plants with nutrient solution, absorbed by the foliage.
  • Fungicide – A formulation that destroys fungus.


  • Granulates – The size of a dry solution that is not quite powder size as it is slightly larger.
  • Growing Phase – The period when plants grows. This usually pre-empts the flower stage.
  • Germination – The development of a plant from seed.


  • HID Lamps – High Intensity Discharge lamps encompasses a range of Hydroponic lighting such as HPS (high pressure sodium) and MH (metal halide). All produce light spectrums that create a natural environment for plants being grown indoors.
  • Hormone – A substance that acts on specific organs and cells to effect growth or change.
  • Hydroponics – Growing plants in nutrient solutions or inert material rather than soil. See Hydroponic Systems.
  • Harden Off – To gradually acclimatize plants harsher environments. Seedling and cuttings need to be hardened-off before going outdoors.
  • Hygrometer – A measuring tool to monitor humidity in the atmosphere. See Thermo/Hydgrometers.


  • Inert Medium – A media form that will not add or take nutrients from feeding solutions. See Grodan.
  • Irrigation – Application of water to soil.


  • Juvenile – The initial period when a plant is incapable of changing to a flowering form of tissue.


  • Long Day Plants – A plant that requires a certain length of time with no light that is shorter than the amount of time it is exposed to light, that induces flowers to form.


  • Metabolism – Biochemical processes that take place in cells in order to sustain life.
  • Mineral – an inorganic element, such as sodium, zinc, potassium, calcium, or iron, that is essential to the nutrition of plants.
  • Mycorrhiza – A group of symbiotic fungi that aid root cells in increasing uptake of water and nutrients.
  • Macronutrients – Primary nutrients N-P-K (nitrogen, phosphorus, and potassium) or the secondary nutrients magnesium and calcium.
  • Media –  The substrate or soilless material which supports the plant and absorbs and releases the nutrient solution in hydroponic horticulture. See Growing Media.
  • Micronutrients – Also known as Trace Elements, including Sulphur, Iron, Manganese, Boron and Copper.


  • NFT (Nutrient Film Technique) – Method in which nutrient is fed in a tray in a thin film where the roots take it up. Allowing roots constant contact with both the nutrient and the air layer above. See NFT.


  • Organic Nutrients – Nutrients bound to organic structure.


  • pH – Measures the acidity or alkalinity of a solution. Scale is 1-14. 1 is acidic, 14 is alkaline, and 7 is neutral. See pH Meters.
  • Photoperiod – The amount of time a plant is or isn’t exposed to light
  • Photosynthesis – A chemical process, created by light. Transforms carbon dioxide from the air into basic organic compounds and molecules used by plants to form sugars
  • Potting Mix – Media developed for Potting, consisting of organic and inorganic materials
  • Propagation Medium – Media specially developed for seedlings or cuttings. See Grodan.
  • Perlite – Sand or volcanic glass, expanded by heat. It holds water and nutrients on its irregular surfaces.


  • Reverse Osmosis – A process in which a very fine filter stops minerals of specific sizes from passing through. This process removes salts and minerals from the water.
  • R.H.P – A Dutch quality standard for Media. Richtlijn Hollandse Potgronden
  • Recirculating System – A system that re-uses drainage water. See Hydroponic Systems.
  • Rockwool – An inert media made of basaltic rock produced by a melting process into fibres. See Grodan.
  • Run to Waste – A system that does not re-use drainage water instead it flows away.
  • Reservoir – A hydroponic system container which holds nutrient solution.


  • Short Day Plants – A plant that requires a certain length of time with no light that is longer than the amount of time it is exposed to light, that induces flowers to form.
  • Substrate – Growing Media that enables roots to grow and the plant to stand up. See Growing Media.


  • Trace Element – Elements that must be in nutrients of an organism for growth. Only a small quantity of trace elements are required
  • Trichoderma – Group of related fungus. Good Trichoderma protect the plant against harmful fungi. There are also ‘bad’ Trichoderma that eat beneficial fungi.


  • V.O.C (Volatile Organic Compound) – are organic chemicals that have a high vapor pressure (scent) at ordinary room temperature.


  • Wick – Using a wick suspended in nutrient solution. Nutrients feed up through the wick and are absorbed by media and roots.