Heaters for controlling the temperature of the nutrient solution or for heating your greenhouses and propagation trays.
Heating mats & cables
Heating mats and cables are very good to heat vast surfaces. They are common as heating below cuttings to accelerate their growth.
Aquarium heaters or special tank heaters to heat up the nutrient solution.
Fan heaters and heater blowers for controlling the temperature in your growing room.
Thermostats to control the temperature in your growing space.