Growing indoors opens up a whole world of terminology, from lighting metrics to soil biology to irrigation systems. This glossary covers the key terms you'll encounter when setting up and running an indoor hydroponic or organic garden. It's written for growers of all experience levels, from first-time seed starters to seasoned enthusiasts looking to fine-tune their setup.
- AC Infinity
- A popular brand of inline fans, grow tents, and environmental controllers designed for indoor growing. AC Infinity products are known for their quiet operation and programmable climate controls, making them a go-to choice for managing airflow and temperature inside grow tents.
- Air pruning
- A natural root-management process that occurs in breathable containers like fabric pots. When a root tip reaches the air-permeable wall of the pot, it dries out and stops elongating, which encourages the plant to produce a denser, more fibrous root system instead of circling the container.
- AQUAvalve
- The patented gravity-fed float valve at the heart of every AutoPot system. It sits in the base of each pot tray and automatically controls water and nutrient delivery without electricity or timers, opening when the tray is dry and closing when it refills to the correct level.
- AutoPot
- A gravity-fed hydroponic growing system that uses the AQUAvalve to deliver water and nutrients from a reservoir without pumps, timers, or electricity. AutoPot systems are valued for their simplicity and low maintenance, making them a strong option for growers who want a hands-off watering solution.
- Ballast
- An electrical device required to regulate the current flowing to HID bulbs such as HPS and Metal Halide lamps. Without a compatible ballast, an HID bulb cannot ignite or operate safely. Modern digital ballasts are dimmable and can often run both HPS and MH bulbs.
- Bluelab
- A New Zealand-based brand that manufactures precision pH and EC meters, monitors, and controllers for hydroponic growers. Bluelab instruments are widely trusted for their accuracy and durability, helping growers keep nutrient solutions within optimal ranges.
- Blumat
- A gravity-fed, ceramic-sensor irrigation system that waters plants automatically based on soil moisture levels. Each Blumat "carrot" is buried in the growing medium and releases water through a thin supply line only when the substrate dries out, making it ideal for living soil and organic setups.
- Carbon filter
- An activated-carbon air scrubber connected to an inline fan inside a grow tent to neutralise odours before air is exhausted. Carbon filters trap volatile organic compounds as air passes through the carbon bed, and they typically need replacing every 12 to 18 months depending on use.
- Clay pebbles (LECA)
- Lightweight Expanded Clay Aggregate, a reusable inert growing medium made by firing clay at high temperatures until it forms round, porous pellets. Clay pebbles provide excellent drainage and oxygen to the root zone, making them a standard substrate in Deep Water Culture and other hydroponic systems.
- Clone / cutting
- A new plant produced by taking a stem or branch from a mother plant and rooting it, rather than growing from seed. Clones are genetically identical to the parent, which allows growers to preserve desirable traits. Propagation domes, heat mats, and rooting gels are commonly used to get cuttings started.
- CO2 supplementation
- The practice of raising carbon dioxide levels inside a grow tent or room above the ambient concentration of roughly 400 ppm, typically to between 1,000 and 1,500 ppm. When paired with high-intensity lighting and proper ventilation, added CO2 can significantly accelerate photosynthesis and plant growth.
- Coco coir
- A growing medium made from the processed husk fibres of coconuts. Coco coir is naturally pH-neutral, holds moisture well while still allowing good aeration, and is considered an inert substrate, meaning it contains no inherent nutrition. Growers feed plants through a nutrient solution, much like in a hydroponic system.
- Deep Water Culture (DWC)
- A hydroponic method in which plant roots are suspended directly in an aerated nutrient solution. An air pump and air stone keep dissolved oxygen levels high, promoting rapid root growth. DWC systems are popular for their simplicity and fast growth rates.
- EC (Electrical Conductivity)
- A measurement of the concentration of dissolved nutrient salts in a water or feed solution, expressed in milliSiemens per centimetre (mS/cm) or parts per million (ppm). Monitoring EC helps growers avoid overfeeding or underfeeding their plants and is essential for managing hydroponic and coco nutrient programs.
- Fabric pot
- A breathable, soft-sided plant container made from geotextile or similar fabric. Fabric pots promote air pruning of roots, prevent root circling, and improve drainage compared to rigid plastic pots. They are widely used in both living soil and coco-based indoor gardens.
- Fertigation
- The practice of delivering dissolved nutrients to plants through an irrigation system rather than applying fertiliser separately. Fertigation is the standard feeding method in coco coir, AutoPot, and drip-irrigated setups, ensuring consistent nutrient delivery with every watering.
- Full-spectrum LED
- An LED grow light engineered to emit wavelengths across the full range of Photosynthetically Active Radiation, including red, blue, and white or green light. Full-spectrum LEDs can be used from seedling through harvest without swapping bulbs, and they run cooler and more efficiently than traditional HID lighting.
- Grow tent
- A portable, light-proof enclosure with a reflective interior lining, used to create a controlled indoor growing environment. Grow tents house lights, fans, filters, and plants in a self-contained space, making it easy to manage light cycles, temperature, and humidity without dedicating an entire room.
- HID grow light
- A High-Intensity Discharge lighting system that produces light by passing an electrical arc through a gas-filled bulb. HID lights include HPS (High Pressure Sodium) and MH (Metal Halide) types and require a ballast to operate. They remain popular for their high light output and proven performance in flowering.
- Inline fan
- A ducted exhaust fan installed inside or at the end of ducting to move air out of a grow tent. Inline fans remove excess heat, control humidity, and work with carbon filters to scrub odours. Variable-speed models allow growers to fine-tune airflow to match their tent size and climate needs.
- IPM (Integrated Pest Management)
- A systematic approach to pest and disease control that prioritises prevention and uses the least harmful intervention first. IPM strategies include maintaining a clean growing environment, introducing beneficial insects, and applying organic sprays only when necessary, rather than relying on a single chemical treatment.
- LED grow light
- A solid-state lighting fixture that uses light-emitting diodes to produce the wavelengths plants need for photosynthesis. LED grow lights are energy-efficient, produce less heat than HID alternatives, and have a long lifespan. They are available in a range of spectrums and intensities to suit different garden sizes and growth stages.
- Living soil
- A biologically active growing medium teeming with beneficial microbes, fungi, and organic matter that work together to break down nutrients and make them available to plant roots. Rather than feeding plants directly with bottled nutrients, growers feed the soil ecosystem, which in turn feeds the plant. Living soil is central to organic and no-till growing methods.
- No-till growing
- A sustainable cultivation method in which the same soil is reused cycle after cycle without being mixed, turned, or replaced. By leaving the soil structure intact, growers preserve the fungal networks and microbial colonies that drive nutrient cycling in a living soil system. Cover crops and top-dressed amendments replenish fertility between plantings.
- Nutrient solution
- A precisely mixed blend of water and dissolved mineral nutrients fed to plants in hydroponic, coco, or fertigation-based systems. A balanced nutrient solution supplies all the macro and micronutrients a plant needs, and its strength is monitored using EC meters while its acidity is tracked with pH meters.
- PAR (Photosynthetically Active Radiation)
- The range of light wavelengths, from 400 to 700 nanometres, that plants can use to drive photosynthesis. PAR is not a unit of measurement itself but defines the "useful" portion of the light spectrum. When comparing grow lights, PAR output is the starting point for understanding how much usable light a fixture actually produces.
- pH
- A scale from 0 to 14 that measures how acidic or alkaline a nutrient solution or growing medium is. Most plants grown indoors perform best in a slightly acidic range of about 5.5 to 6.5. Keeping pH in the correct window ensures nutrients remain available for root uptake rather than locking out.
- PPFD (Photosynthetic Photon Flux Density)
- The number of photosynthetically active photons landing on a given surface area per second, measured in micromoles per square metre per second (µmol/m²/s). PPFD is the most practical metric for comparing grow light intensity at canopy level, and target values vary by growth stage and plant species.