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Heating for tents and propagators through cold nights
UK grow rooms lose heat fast once the lights switch off, and a cold snap overnight can drop veg temperatures below where roots want to work. A 45W propagation heat mat (from £29.95) sits under trays of cuttings or seedlings and lifts medium temperature by a few degrees — the difference between clones rooting in a week and clones sulking for two. Pair it with a thermostat if you're propagating through winter, since a mat left running flat out can cook a tray of rockwool cubes dry.
For the wider room, a Lighthouse 2KW grow room heater (£39.95) with its own thermostat holds ambient temperature in an unheated space, while Hailea water heaters (from £14.95) go into reservoirs and tanks to keep root-zone water warm — cold feed water is an underrated cause of slow uptake in winter hydro setups. Tube heaters are also worth considering for tents where a fan heater's airflow would disturb the canopy.
Getting the target right
Seedlings and cuttings want 22–26°C, established plants in veg 24–28°C — see the full stage-by-stage table in our grow tent setup guide. Overheating a propagator is as common a mistake as underheating one, so always run a heat mat through a thermostat rather than straight to the mains. Free UK delivery over £99, Express Delivery available on most heaters.