Keeping your grow tent cool in the summer can be a challenge. In this article we’ll cover our top tips on how to cool a grow tent or even a grow room.
Note: If you click some of the links in this article we may earn a small commission at no additional cost to you.
Why Is Your Grow Tent Heating Up?
Grow tents heat up for a variety of reason. It’s good to review your situation and compare them to these to see where your problem lies.
- Lack of proper ventilation or an optimized ventilation system
- Grow tent is located in a hot room (e.g. attic, too many windows, south facing room of house)
- Lights aren’t optimized or are too hot for the setup
- Ventilation system isn’t clear or is malfunctioning
- Inadequate growing space – ratio of lights to grow tent is too high
In the next section we’ll cover 27 ways to deal with overheating grow tents.
Top 27 Tips On How To Cool a Grow Tent or a Grow Room
Tip 1 – Know Your Temperatures
Ideal growing temperatures range from 70 – 80 Degrees Fahrenheit during the day and 65-70 Degrees F at night.
This is the temperature you should be aiming for. If possible install a thermometer both at plant level and another one at the top of the tent. This will help you check for proper ventilation and improve air movement.
Tip 2 – Use Air Cooled Grow Lights with Inline Ventilation Systems
Most grow lights have passive ventilation by cutting ventilation ports in the side of the light housing.
Some use active ventilation with inline fans and air ducts to air cool the grow lights. Consider switching to air cooled grow lights.
Tip 3 – Use Water Cooled Grow Lights
As with air cooled lights, you can also use water cooled grow lights. Water cooled lights have a smaller shadow footprint which works great for use in grow rooms utilizing natural sunlight in addition to LED lights.
Tip 4 – Don’t Grow in the Attic
Attics will pose serious heat risks. If you can move your grow tent to another room or the basement. This tip falls into the category of fixes where you try and cool the room around the grow tent.
Tip 5 – Insulate the Grow Room In Combination with Adding AC
If you can’t leave the attic consider insulating the grow tent or grow room and adding active air conditioning.
Tip 6 – Grow Rooms – Use Light Movers To Move Heat Around Room Evenly
For a larger grow room with uneven or high temperatures, consider using a light rail to move the lights around and distribute the heat.
Tip 7 – Add Hydroponics with Reservoir Chillers
Adding a hydroponic setup let’s you control the temperature of the water. Combined with a reservoir chiller, inline pumps, and water lines, this setup makes for an effective way to lower high temperatures in your grow room.
Tip 8 – Add Frozen Ice Bottles Daily
Fill up some gallon jugs with water and freeze them. Add them to the grow tent daily. Freeze them nightly.
It’s more work than an AC but cheaper!
Tip 9 – Check For Bends or Breaks in Ventilation Tubes
Each bend in ventilation tube can reduce efficiency by 5% or greater.
Also check that the tubes are clear of any debris (or dead animals).
Tip 10 – Add a Cooling Humidifier to Increase Relative Humidity
Top filling cooling humidifiers are somewhat cheaper than AC units. The top filling types are easier to refill and maintain. Increasing relative humidity can also be great for your plants in drier environments like Colorado and the arid west.
Tip 11 – Optimize the Lights
Check that your lights are optimized:
- Are the ventilation ports on the lights clear?
- Are they hanging low enough from the top of the grow tent to ensure adequate air movement?
- Are the lights too hot for the small space? Can you switch to colder LED lights?
Tip 12 – Use LED Lights Instead of Halogen Or Hotter Lamps
Tip 13 – Move the Grow Tent Into a Cooler Room or Basement
Can you move your small grow tent to another room?
Tip 14 – Move the Grow Tent Away from Windows
Can you move your grow tent away from the windows/
Tip 15 – Block the Windows In Your Grow Tent Room
If you can’t move the grow tent away from the windows consider using blackout blinds to block the windows and cool the room overall.
You can also open the windows to let in cool air at night.
Tip 16 – Open All the Ventilation Ports
Check that every light ventilation port is open and clear.
Check also that any ventilation ports or exhaust fans going in and out of the tent are also open and free flowing.
Are you using a carbon filter to reduce odors? Is it blocked?
Tip 17 – Add a Commercial Air Conditioning Unit
This is one of the easiest ways to solve it if you have the money and space. Simply buy a commercial air conditioning unit and install it.
You can use a large unit for the entire room like the unit below.
Or you can use a small unit inside the grow tent.
Tip 18 – Install a DIY Air Conditioning Unit
You can also build your own DIY air conditioning unit. These require daily maintenance though like the frozen bottles.
Tip 19 – Use Timers For the Minimum Light Time Needed
Are your lights on too long each day? Use timers and give your plants just what they need to keep them cool.
Tip 20 – Add a Intake and Exhaust Fans
This is one of the most common solutions. Simply actively push air into and out of the grow tent. It works best when you have both to help fully circulate air movement inside the grow tent.
Tip 21 – Optimize Air Flow – Are Your Fans Too Small?
If you already have air flow added, perhaps it’s not moving enough air?
Use multiple thermometers spread at the top of the tent, bottom of the tent, and around the room. Or simply use one thermometer and move it to these locations noting the temperature at each.
Tip 22 – Add Oscillating Clip-on Fans To Circulate Air Inside the Tent
This is a classic, easy trick to cool a tent. As in the tip above, you need to check that a small oscillating clip-on fan will move enough air to keep things cool.
Tip 23 – ADVANCED – Use a Carbon Dioxide Cooling System
Adding carbon dioxide gives plants more of what they need (CO2 and light) plus it can help cool the room down.
This is a more advanced method as you need to monitor the CO2 ppm levels both for your plant’s health and for your safety.
We find a good $40 air conditioner is an easier option.
Tip 24 – Add Fans to Grow Lights or Use Grow Lights With Working Fans
Do you have air cooled lights without any ventilation equipped?
Can you add ventilation to your existing lights?
Tip 25 – Check That Any Existing AC Units or Exhaust Fans are Working and Clean
Run this check every year, ideally a few times a year.
Tip 26 – Check That Any Glass Panels On Your Grow Lights Have Ventilation and That’s It’s Clean and Clear
This should be the case but it’s best to check this yearly.
Tip 27 – Operate Grow Lights At Night Instead of the Day
This last trick can save you the time of opening the windows at night and closing them during the day. It works best if you block the windows in the grow tent room with black out blinds as well.