A to Z of Urban Farming Techniques

An authoritative glossary of urban farming terms β€” from hydroponics to vertical farming.

A

AeroponicsAeroponics is a soilless growing method where plant roots are suspended in air and misted with a nutrient solution at regular intervals.Air PumpAn air pump (aquarium or diaphragm pump) is a device that forces air through airline tubing and air stones submerged in a hydroponic nutrient reservoir, producing fine bubbles that increase dissolved oxygen levels in the solution.AquaponicsAquaponics combines fish farming (aquaculture) with soilless plant cultivation (hydroponics) in a closed-loop ecosystem.

B

Beneficial BacteriaBeneficial bacteria are microorganisms that, when introduced to the root zone or growing medium, actively improve plant health, nutrient availability, and disease resistance.BoltingBolting is the premature transition of a vegetable plant from vegetative growth to flowering and seed production, triggered by environmental stresses such as high temperatures, long day-length, or drought.

C

Cal-MagCal-Mag is a liquid hydroponic supplement combining Calcium (Ca) and Magnesium (Mg), two secondary macronutrients that are frequently deficient when growing in soft water, coco coir, or with certain base nutrient formulas.Carbon FilterA carbon filter (also called a charcoal filter or carbon scrubber) is an odour control device used in indoor growing spaces.Chelated IronChelated iron is iron (Fe) that has been chemically bonded to an organic molecule (a chelate) to keep it soluble and plant-available in nutrient solutions.Clay PebblesClay pebbles (also called hydroton, LECA β€” Lightweight Expanded Clay Aggregate, or clay balls) are small, porous balls made by firing clay in a rotary kiln.Coco CoirCoco coir is a natural growing medium made from the fibrous husk of coconut shells.CompostingComposting is the controlled biological decomposition of organic matter β€” such as food scraps, garden waste, and paper β€” into a nutrient-rich soil amendment called compost.

D

Deep Water CultureDeep Water Culture (DWC) is a hydroponic system where plant roots are suspended directly in a reservoir of aerated, nutrient-rich water.Dissolved OxygenDissolved oxygen (DO) refers to the concentration of oxygen gas (Oβ‚‚) dissolved in the nutrient solution and available to plant roots.Drip SystemA hydroponic drip system delivers nutrient solution to individual plants through thin tubes fitted with slow-release drip emitters.

E

Ebb and FlowEbb and flow (also called flood and drain) is a hydroponic system where a grow tray is periodically flooded with nutrient solution from a reservoir below, then allowed to drain completely.

F

FogponicsFogponics is an advanced variation of aeroponics where ultrasonic foggers or humidifiers create an ultra-fine nutrient mist (fog) with droplet sizes of 5–30 microns β€” far smaller than standard aeroponic nozzles.

G

GerminationGermination is the process by which a seed emerges from dormancy and begins active growth, producing a radicle (embryonic root) and a shoot.Grow TentA grow tent is a portable, enclosed indoor growing space made from a metal frame covered with lightproof, reflective fabric.

H

Hydroponic TowerA hydroponic tower is a vertical growing system where plants are inserted into ports arranged in a column, and a nutrient solution is pumped to the top and cascades down through the root zone of each plant in turn.HydroponicsHydroponics is a method of growing plants in nutrient-rich water solutions without soil.

I

IPMIPM (Integrated Pest Management) is a systematic, multi-layered approach to managing plant pests and diseases that minimises the use of chemical pesticides.

K

Kratky MethodThe Kratky method is a passive, non-circulating hydroponic technique where plants grow above a reservoir of nutrient solution without pumps or electricity.

L

LED Grow LightsLED grow lights are energy-efficient artificial lighting fixtures designed to emit specific light spectra that drive plant photosynthesis.Light CycleA light cycle (or photoperiod schedule) is the programmed on/off timing of grow lights in an indoor growing environment, expressed as hours of light followed by hours of darkness (e.Light SpectrumLight spectrum refers to the distribution of wavelengths emitted by a grow light source.LumensLumens are a unit measuring the total amount of visible light emitted by a source as perceived by the human eye.

M

MacronutrientsMacronutrients are the mineral elements that plants require in large quantities for healthy growth.MicrogreensMicrogreens are the seedling stage of vegetables, herbs, and grains, harvested 7–21 days after germination when the first true leaves appear.MicronutrientsMicronutrients (also called trace elements or minor nutrients) are mineral elements that plants need in very small quantities but that are nonetheless essential for healthy growth.

N

Net PotA net pot (also called a net cup or mesh pot) is a small plastic container with an open lattice or mesh wall structure, used in hydroponic systems to support plant roots while allowing nutrient solution to flow freely through the sides and base.NPKNPK refers to the three primary macronutrients in any fertiliser or nutrient solution: Nitrogen (N), Phosphorus (P), and Potassium (K).Nutrient Film TechniqueNutrient Film Technique (NFT) is a hydroponic method where a thin, continuous stream of nutrient solution flows along the bottom of sloped channels over bare plant roots.Nutrient LockoutNutrient lockout occurs when plants are unable to absorb one or more minerals from the growing medium or nutrient solution, despite those nutrients being physically present.Nutrient SolutionA nutrient solution is the water-based mixture of dissolved mineral salts that delivers all essential plant nutrients directly to roots in hydroponic systems.

P

PARPAR (Photosynthetically Active Radiation) is the range of light wavelengths β€” from 400 nm (violet) to 700 nm (red) β€” that plants can use for photosynthesis.PerlitePerlite is a lightweight, porous volcanic glass that has been heated to extremely high temperatures until it expands into white, popcorn-like granules.pHpH is a measure of the acidity or alkalinity of a solution on a scale from 0 to 14, where 7 is neutral.PhotoperiodPhotoperiod refers to the daily duration of light exposure a plant receives.PPFDPPFD (Photosynthetic Photon Flux Density) measures the amount of photosynthetically active light (400–700 nm) delivered to a plant's surface per second, expressed in micromoles per square metre per second (Β΅mol/mΒ²/s).PruningPruning is the deliberate removal of plant parts β€” leaves, shoots, stems, or flowers β€” to direct the plant's energy, improve air circulation, manage plant size, and increase yield quality.

R

Recirculating SystemA recirculating hydroponic system (also called a re-circ or closed-loop system) is one in which nutrient solution is continuously or periodically pumped from a central reservoir to the plants and then drained back into the same reservoir for reuse.ReservoirIn hydroponics, a reservoir is the container that holds the mixed nutrient solution and supplies it to plant roots.Reverse OsmosisReverse osmosis (RO) is a water purification process that forces water through a semi-permeable membrane under pressure, removing up to 95–99% of dissolved salts, minerals, chlorine, chloramines, and other contaminants.RockwoolRockwool (also called stonewool or mineral wool) is an inert growing medium made by melting basalt rock and spinning it into fibres, then pressing it into cubes, slabs, or granules.Root RotRoot rot is a plant disease caused by pathogenic water moulds (primarily Pythium and Phytophthora species) that attack and decompose plant roots in waterlogged or poorly oxygenated conditions.RunoffRunoff (or drain-to-waste) refers to the nutrient solution that drains out of a growing medium after each irrigation cycle and is not recirculated.

T

Tip BurnTip burn is a physiological disorder in leafy crops β€” most commonly lettuce β€” where the edges and tips of inner leaves turn brown and die.TransplantingTransplanting is the process of moving a seedling or young plant from its initial propagation medium into the main growing system.

V

VermiculiteVermiculite is a naturally occurring mineral (hydrated magnesium aluminium silicate) that expands into accordion-like particles when heated to high temperatures.Vertical FarmingVertical farming is the practice of cultivating crops in stacked horizontal layers inside controlled indoor environments.VPDVPD (Vapour Pressure Deficit) is the difference between the amount of moisture in the air and the maximum moisture the air can hold at a given temperature.

W

Wicking SystemA wicking system is the simplest form of passive hydroponics, where an absorbent wick draws nutrient solution from a reservoir up into the growing medium by capillary action.
A to Z of Urban Farming Techniques | grow.food