How To Cool A Grow Tent

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Brad Smith
Written By Brad Smith

How do you maintain optimal temperatures when growing plants indoors? This is probably the biggest challenge many cannabis growers face when maintaining the right temperatures for their plants. Nonetheless, there are several ways to grow fresh produce year-round in your basement or even that empty closet in your house.

A grow tent is your best bet to cultivate your marijuana indoors.

But the temperature in your grow room gets high since they are tightly sealed. So how do you ensure that the grow tent maintains the right temperature for your plants to grow healthily?

This article tackles the various ways you can lower the temperature in your grow tent. It also answers most of the questions indoor marijuana growers are curious about regarding indoor growing.

What Is A Grow Tent?

A grow tent is a collapsible tent that allows you to grow your plants indoors in places that ideally wouldn’t be used to grow plants. The best grow tents are made of reflective material to prevent hot spots. They are ideally lightproof, waterproof, and have airtight vents. A grow tent should also include fans, lights, and a carbon filter.

With grow tents, you can have a whole garden ecosystem in your house where you can grow and yield healthy marijuana plants. The best part about grow tents is since they are relatively small and are located away from other plants, they are mostly pest and disease-free. Nevertheless, you should control be keen on controlling the air circulation in the tent to ensure that your plants do not get mold or fungus.

What Should The Temperature Be In My Grow Tent?

Temperature is a critical variable when you are growing marijuana. When your grow tent is too warm, your plant could kill your plants. Conversely, when the temperature drops too low, your plant’s growth gets stunted, and it eventually dies.

It is best to aim for temperatures between 70-85°F (20-30°C).

During the vegetative state, do well in this maximum temperature. However, at the flowering stage, the grow room can be cooler at 65-80°F (18-26ºC).

How Hot Is Too Hot For Grow Tent?

excess heat

Most gardeners argue that they can grow their plant at 33°C comfortably with no negative effect on the marijuana. Others claim that this temperature kills their beloved plants. So, how hot is too hot?

Ideally, any temperature beyond 86 °F (30°C) should be avoided. Some strains thrive in slightly higher temperatures, but you want to maintain the optimal temperature in the grow tents to get the best yield out of your plant.

What Turns a Grow Tent Hot?

Before you understand how to cool a grow tent, it is necessary to learn what makes it turn hot. Here are several factors that make your grow tents heat up :

  • Lights: Growing lights are the largest contributor to heat in your grow room. You can solve this problem by situating the lights a little further from your plants. Alternatively, find lights that are air or water-cooled to protect your plant from heat.
  • Lack of proper ventilation could raise the temperature inside the grow. When plants are outdoor under the sunlight, what prevents them from withering is fresh air circulation. You should have a ventilation system that will ensure proper airflow in the grow to retain the same optimal environment.
  • If your grow space is located in an area with hot surroundings, it can make it hard for the air conditioning to bring down the temperature to an optimal level.
  • Improper insulation can also cause your tent to turn too hot. This is especially true in areas that experience summer climates.

How Can I Cool My Grow Room In Summer?

The high temperature outside during the summer can negatively affect the plants in your growing space if it is not well ventilated. But there are practical ways to lower the temperatures in your indoor garden space. First, place the grow tent in a cooler part of your house. Secondly, switch your HID lights or HPS to LED lights. LEDs produce less heat. Thirdly, keep the room cool by having your fan blow the air out of the window and not into the room where the marijuana garden is located.

Also, depending on the size of your grow, you can be smart about fan placement to harness the most cooling power for your plants.

These steps will keep the ambient temperature in your indoor garden cool enough for your plants to thrive.

The Best Ways To Keep Your Grow Tent Cool

grow light

1. Switch to LED Grow Lights

As previously mentioned, lighting plays a major role in heating a grow room. LED lights are the best to install if you want to cool a grow. They produce less heat and use less power to give you the same amount of light you would get from an HID. They are also more efficient.

It is important to add that some LED grow lights come with removable drivers. If you purchase this kind of grow lights, ensure you place these drivers outside your grow tents to reduce the amount of heat inside.

2. Optimize Your Grow Lights

Optimizing your grow lights will lessen the impact lighting has on your growers. Some of the ways you can do this include:

  • Raise the grow lights. It helps prevent direct heat impact to your plants. Keep your lights a fair distance away from our plants.
  • Run the lights at night . Temperatures are generally cooler at night, thus offsetting the heat being emitted by the grow lights. What’s more, this option could be cost-effective for you since some power companies lower their electricity rates at night.
  • Install a grow light mover. Having the lights on one spot could create hot spots in the grow tent. Additionally, when there is no uniform distribution of light in the grow tent, some plants could die as there is no photosynthesis taking place. Having uniform light distribution in the room also reduces canopy overgrowth.
  • Use water-cooled or air-cooled grow lights: These types of grow lights reduce the hot air emitted by standard lights. Water-cooled lights are designed to use water to transfer the heat from the LEDs efficiently, thus not allowing any hot air into the grow room. When installed in a perfectly sealed grow space, they can serve the purpose of an air conditioning system.

Another great way to cool a grow tent is by using air-cooled lights. To have them working effectively, install them along the duct lines to pass the hot air from the bulbs out of the growing room. Ensure you have properly insulated your grow tent to boost the cooling process.

3. Proper Ducting and Insulation

proper ventilation

When setting up your ventilation system, ensure your ducting is done perfectly. Ducting ensures that you insulate the airflow inside to cool a grow tent. Experts state that right-angle bends can reduce the function of fans inside your garden by 5%. This means the more turns you have, the harder the fans have to work. So, if possible, avoid many right-angle bends in your grow tent to allow better air transfer and less heating.

Another issue you need to address when ducting is lighting. Your grow tent should be lightproof. There should be no light entering through the ducts. This is critical, especially during the flowering stage of your marijuana, because at this stage, it needs 12 hours of darkness every day. Lightproof ducting can help deal with this.

As you insulate the interior of your grow tent, how about the area where it sits? It is important that you place it in a place where the warm air from outside will not impact it in any way. An ideal location may include a basement since it is not under a hot roof. Similarly, don’t locate your tent in the south-facing exterior wall.

If you have central air conditioning, you should consider placing your grow tent near the air vents. Alternatively, you could place it near an open window. This will allow you to directly route your ducting from the tent to the outside environment via the window.

4. Add Carbon Dioxide (CO2) To your Tent

While this method does not cool your grow tents, it could boost the CO2 levels for your plants. Your marijuana may be able to withstand higher temperatures. If you find it challenging to maintain the optimum temperature within your grow space, these CO2 bags will be your best bet at getting healthy plants. What’s more, they will last the entire grow and will not have you breaking the bank.

5. Turn on The AC

air conditioner

To cool a grow tent, get a portable air conditioner and place it in the room where your tent is situated to control the cool air circulating. If cooling the room does not help, try placing it inside the grow tent to lower the temperature inside. However, this will work if you have a bigger grow tent.

How To Cool Grow Tent Without AC?

Using air conditioners to cool your grow tent can be an expensive affair, especially if you are growing your marijuana for personal use. Here are other available options for cooling that do not require using an AC:

1. Fans

Marijuana growers know the importance of having regular cool airflow in the grow tent. Fans are a less expensive way of cooling your grow tent than having air conditioners installed. There are three types of fans for grow spaces:

  • Inline Fans: These are fans in the ducting to take care of the air intake and air exhaust. They exhale the hot air and intake the fresh, cooler air. Ideally, the inline fans should replace the air inside your grow tent once per minute.
  • Oscillating fans: They constantly circulate cool air inside the grow tent. Depending on the size of your grow, you may need more than one oscillating fan for even air exchange within the tent. This prevents mold from growing on your plants.
  • Exhaust Fans: These are perfect for pulling excess moisture, and unpleasant odors out of your grow tent. You can place your exhaust fan by venting it into the room if it is well air-conditioned. If this does not work for you, consider ducting the air out of the tent through a window or away from the location of the grow tent.

You may also need to attach a carbon filter to the exhaust fan to trap the odor of the weed before letting it out to the outside world.

One major factor you may need to consider is how you place the fans in the grow tent. The wrong placement could lead to the same hot air within the tent circulating instead of fresh, cooler air.

2. Use A Swamp Cooler

A swamp cooler is an alternative way to cool a grow tent. It is a more efficient cooling system than a standard air conditioner. If you need to increase the humidity level in your growing environment, these coolers will come in handy. They cool the air through the evaporation of water.

3. Reservoir Chillers

When using a hydroponic set up to grow marijuana in a grow tent, most gardeners use reservoir chillers inside the tent. However, one way to cool your grow tent is to consider relocating them outside the tent to eliminate excess heat inside the tent. Additionally, when they are placed inside the growing environment, dangerous algae can grow in the water when temperatures go beyond 70 degrees.

4. Use Dry Ice

This method does not require you to buy any equipment. It also requires less maintenance. This is the easiest way to keep the temperature in your tent low. You can make your box of ice using DIY materials in your home like a bucket.

Depending on the size of your indoor grow tent, you can place the box of dry ice in a container and place an oscillating fan near it to reduce the amount of heat in your tent. Dry ice produces enough CO2 to allow plants to thrive at a higher temperature than normal.

5. Water Chillers

Water chillers are another ideal option to maintain lower temperatures in your indoor garden. They are electric devices that serve a dual purpose. They keep the humidity in the grow tents high while absorbing moist vapors and leaving the cooler air for your plants. You can find water-cooled and air-cooled chillers in the market which perform the same function.

There are other products in the market that do not cool air themselves but work perfectly to avoid heat generation:

  • Smart Pots: They are fabric pots that are great at providing your plants’ oxygen from the roots. When you house your marijuana in smart pots, there is less evaporation, effectively decreasing the chance of overheating.
  • Supplements and Nutrients: Some supplements and nutrients help protect your marijuana by making them more heat resistant or recover more quickly from heat stress. However, given the various companies producing different supplements and nutrients, it is advisable to buy from one company to avoid confusion.
  • Use the light dimming function to reduce the amount of heat emitted by grow lights.
  • Reflector Hood Lights: Air-cooled reflectors are perfect for reducing heat in your growing space. They reduce the amount of heat in the garden by running a stream of air from a fan through the reflector via an air vent or an exhaust vent. Reflectors also focus the light emanating from the grow light to the plant. This process enables photosynthesis to take place.


What are the best tips and tricks for setting up a cooling grow tent?

For an effective tent setup, prioritize LED lighting to reduce heat, use proper ducting techniques, and employ strategic placement of oscillating fans. It’s also helpful to integrate an AC unit and ensure proper insulation, possibly with materials like aluminum foil, to maintain optimal air temperature.

Can you suggest any techniques for maintaining temps in a growing tent during drying and harvest?

During the drying and harvest stages, control temps by adjusting your AC unit, using a dehumidifier, and maintaining steady air circulation. Techniques like avoiding over-insulation and monitoring the tent’s internal temperature frequently are crucial.

How do I keep my tents cool without an AC unit?

Cooling a grow tent without an AC involves methods like using water chillers, positioning your tent away from heat sources, optimizing air circulation with fans, and possibly utilizing homemade cooling strategies like a DIY swamp cooler.

Are there any specific methods to manage air temperature and humidity in my tent growing space?

Managing air temperature and humidity can be achieved through a combination of proper ventilation, using ballasts that generate less heat, maintaining a consistent watering schedule, and using a hygrometer to monitor conditions. Employing these strategies is essential for a balanced growing environment.

Could you provide some strategies for beginners setting up their first growing tent?

For beginners, start with understanding the basics of your tent setup, including the placement and type of lights (LEDs are preferred), ensuring adequate ventilation, and understanding the role of components like ballasts. Tips like starting with a smaller tent and experimenting with different cooling methods can also be helpful.

Final Thoughts

This complete guide lists the options available to cool a grow tent to get the yield you want. With the information provided above, it is evident that marijuana does not do well with heat.

From costly options to the less expensive ones, you can find a solution that is well suited to your indoor garden.

Some options are also based on the size of your indoor garden.

In conclusion, it is important to realize that once you consider growing your marijuana, it will take a lot of time, money, and effort to maximize growth and produce the best yield.

Further Reading

  • For enthusiasts looking to optimize their grow space lighting while ensuring their setup remains cool and efficient, our latest guide on the ‘Best 5×5 LED Grow Lights: My Top Picks for Maximum Yield‘ offers invaluable insights and recommendations to elevate your indoor gardening. Explore our top picks to find the perfect lighting solution that balances intensity with energy efficiency, complementing your cooling strategies for a thriving grow tent.
  • To ensure your plants thrive in the perfect environment, explore our comprehensive guide on selecting the best humidifier for your grow tent, a crucial companion piece for maintaining optimal humidity levels alongside temperature control.
  • For enthusiasts aiming to optimize their grow tent’s lighting system for enhanced plant growth while maintaining ideal temperature levels, explore our comprehensive guide on the Best 4×4 Grow Tent LED Lights. This resource provides in-depth insights into selecting the right LED lighting solutions that complement your cooling strategies, ensuring your plants thrive in the perfect environment.
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Written by Brad Smith

CEO & Lead Interior Designer

Brad Smith is an experienced interior designer and the founder of With a Master's degree in Interior Design from Pratt Institute and a passion for creating safe and healthy living spaces, Brad shares his expert insights and innovative design ideas with our readers. His work is driven by the belief that home is where every story begins.