A grow tent is a lightweight frame covered in light-proof fabric with a reflective inner lining, zip doors and sealable ports for ducting and power. Tents are sized by footprint, in feet (2x2, 2x4, 4x4, 5x5) or centimetres (60x60, 120x120).
In practice
Size the light and fan to the footprint. A 4x4 ft (1.2x1.2 m) tent in flower typically runs about 600-1,000 µmol/m²/s at the canopy, and an inline fan exchanges the tent's air roughly once a minute through a carbon filter. Keep negative pressure (fabric slightly sucked in) so smell exits through the filter, and check for light leaks with the lights off inside the tent in a dark room, especially at zips and ports, because leaks during the dark period can stress photoperiod plants in flower.
Don't confuse with
- Grow room: a room built or converted for growing; usually larger and harder to seal.
- Grow cabinet: a rigid box, often with built-in light and fans.
Photosynthetic photon flux density: the number of PAR photons landing on one square metre each second, in µmol/m²/s; the standard measure of light intensity at the canopy.An exhaust fan pulls air out of the grow space through ducting, removing heat, humidity and odour and drawing in fresh air.A carbon filter scrubs odour from exhaust air by passing it through activated carbon, which adsorbs aroma compounds such as terpenes.Negative pressure means the grow space is held slightly below surrounding air pressure by exhausting more air than comes in, so air and odour leak inwards, not out.A light leak is unwanted light entering the grow space during the dark period; in flower it can delay or disrupt flowering in photoperiod cannabis.The daily length of light versus dark; photoperiod cannabis flowers when nights grow long enough, rather than at a fixed age.A large palmate cannabis leaf with several long leaflets on a long petiole; fan leaves do most of the plant's photosynthesis and carry few trichomes.Airflow is the movement of air through and around the canopy; it thins the still boundary layer on leaves, evens out temperature and humidity, and lowers mould risk.Vapour pressure deficit: how much more water vapour the air could hold at its temperature, in kPa; it is the main environmental driver of transpiration.
