Combat Cold Temperatures in Your Grow Room or Greenhouse
How to Combat Cold Temperatures in Your Grow Room or Greenhouse
As temperatures start to drop, indoor growers and greenhouse gardeners face a new challenge: keeping plants happy, healthy, and productive in the cold. While many think greenhouses or grow rooms are naturally protected, low temperatures can sneak in and cause serious problems — from stunted growth to poor yields.
Here at GHEDirect, we know how crucial environmental stability is for plant success. Here’s what you need to know about the effects of cold on your plants, and how to protect your grow space when the temperature dips.
Why Cold Temperatures Are a Problem
Plants, like people, have an optimal temperature range. When it drops below this range, a lot can go wrong:
Slowed Growth: Cold conditions reduce metabolic activity, meaning plants take longer to grow and develop.
Nutrient Lockout: Chilly root zones can cause nutrient absorption issues — your plants might show signs of deficiency even when your feed is perfect.
Poor Germination: Seeds and young seedlings are especially sensitive to cold, often failing to sprout or develop properly.
- Humidity Imbalance: Cooler air holds less moisture, leading to low humidity levels that stress plants and cause leaf curling or crispy edges.
Condensation & Mould Risk: When warm, moist air meets cold surfaces, condensation forms — creating an ideal environment for mould and mildew.
How to Combat the Cold in Your Grow Room or Greenhouse
1. Use Efficient Heating
A grow room heater or greenhouse heater is your first line of defense. Use thermostats with your heaters to maintain consistent temperatures. For hydroponic systems, tank heaters keep root zones stable even when air temps drop.
ORA 2KW Fan Heater
Lighthouse EcoHeat Greenhouse Bar Heater
Hailea Tank Heaters
Biogreen Thermo 2 Digital Thermostat
GAS Day & Night 2KW Heater Controller
2. Insulate Your Space
Good insulation keeps warm air in and cold air out:
- Use thermal bubble wrap or insulating film on greenhouse panels.
- Be sure to seal gaps around doors, vents, and windows.
In grow rooms, use insulated foam board or reflective sheeting to retain heat.
Mylar – Silver White Lightite
3. Warm the Root Zone
Cold roots equal unhappy plants. Try:
Heating mats under propagation trays.
Tank heaters for hydro systems.
Ensuring pots aren’t sitting directly on cold floors — elevate them slightly using pallets or foam boards.
Heat Mat Propagator Bundle
Root!t Heat Mat Bundle
Root !T Hobby Heat Mats
4. Maintain Air Circulation
Warm air rises — so without fans, your canopy might stay cool while heat collects near the ceiling. Use oscillating fans to circulate air evenly and prevent cold spots.
RAM 18 Inch – 450mm Heavy Duty Wall Fan
RAM AirFLEX Rotating Grill Clip Fan
DiffuseAir Fan Diffusers
5. Monitor Temperature & Humidity
Biogreen Thermo 2 Digital Thermostat
ThermoPro TP358 Thermo-hygrometer
6. Climate Control
SMS Smart Fan Controller 6.5 Amp
GAS Enviro Controller V2
SMS Hybrid Pro Fan Controller
7. Adjust Lighting Schedules
If you are struggling to get your grow room warm enough during ‘lights on’, particularly if using LED’s only, consider adding in some HPS or Metal Halide lights as they will add not only extra light but also extra heat, especially radiant heat that can help prevent moisture build up in flowers.
Maxibright Maxiswitch Quad Plugin Timer 13A
LUMii Lighting Contactors
Seasonal Growing Tips
Feed Wisely: Cooler conditions mean slower nutrient uptake — consider slightly lighter feeding to prevent salt buildup.
Reduce Watering: Plants use less water in the cold. Overwatering can lead to root rot.
Pre-Warm Water: If you’re using hydroponics or watering from a tank, ensure water isn’t cold. Aim for around 20–22°C for best nutrient absorption.
Seasonal Growing Tips
Cold weather doesn’t have to slow you down. With proper insulation, heating, and monitoring, you can maintain a stable environment and keep your plants thriving through winter.
At GHE Direct, we supply professional growing equipment to help you maintain perfect conditions year-round — from heaters and insulation materials to climate controllers and sensors. Explore our full range of products designed to keep your grow room or greenhouse at peak performance, no matter the weather outside.
