How To Cool A Grow Tent Without AC (How To Cool A Grow Tent Without Wasting Tons Of Money)

A combination of lights, equipment, and confined spaces means your grow tent can quickly overheat during the summer. The easiest way to keep cool is with an AC unit, but if you don’t have one, there are a few low-cost solutions worth trying.

How To Cool A Grow Tent Without AC

The quickest and most effective way to cool a grow tent without AC is with an oscillating fan. But changing your lights — and changing when the lights come on — also make a difference.

Keep reading to find out how to keep your grow tent cool on a budget.

How Can I Cool My Tent Without AC? 

Cannabis is a relatively hardy plant, but the wrong conditions can massively impact your yield. If your grow tent gets too warm, you can expect smaller buds and overall lower growth.

If it’s very warm, you’ll probably need to use several methods to keep your grow tent at the right temperature. Invest in a digital thermometer, so you can accurately measure the temperature and the effects of your cooling efforts.

Check The Ventilation

A grow tent of good quality should come with built-in ventilation that you can close or open, depending on the temperature. If your grow tent is getting hot, the first step is to check that it’s ventilated properly.

You can also add your own ventilation to the grow tent. Try leaving the door open, or making a few strategic cuts at the top of the tent to let hot air out.

Use LED Bulbs

If you’re using HPS or MH grow lights in an already hot tent, these inefficient bulbs will only put out more heat. Instead, switch to LED lights. LED is a more efficient form of lighting that doesn’t give off the heat of older bulbs.

LED lights can be more expensive upfront, but nowadays, they’re readily available at a decent price. Plus, the switch to LED will lower your electricity bills.

Automate The Climate

Automating when the LEDs turn on and off ensures your cannabis plants get the light they need for healthy growth, and no more than that! 

Even energy-efficient LED bulbs will give out heat. If they’re left on for long hours of the day, you might be increasing the overall temperature of your grow tent.

If you aren’t around to turn the lights on and off every single day, automating can prevent accidental heat increases.

Add A Fan

Adding a fan is the quickest and easiest solution for quickly cooling down your grow tent. An ideal solution would be to combine an oscillating fan with an exhaust fan to get air circulating and pull hot air away.

But if you want to keep costs down, an oscillating fan is the best solution. Keep it in the grow tent if you can, where it will circulate the air to help keep it cool. If you have a particularly big tent, you might want to use several fans.

You might be working on a budget, but it’s better to spend a little more money to get a good fan. A low-quality fan will heat up as it works. While that might not be a problem in a big room, in a small grow tent, it’s an issue.

Use Buckets Of Ice

A low-tech solution, but one that works! Fill a bucket with ice, and put that bucket in the grow tent. Once it’s melted, switch the water to fresh ice, and start again! Buckets of ice will increase the humidity level in the tent, so keep that in mind if you use this method.

Add A Swamp Cooler

A swamp cooler is a fairly rudimentary form of air conditioning. The main advantage to a swamp cooler is that you can make a basic version at home with a fan, a bucket, a towel, and some ice, for a low-cost alternative to AC.

A swamp cooler will add more moisture to the air, so avoid this option if you have a good humidity level already.

How Hot Is Too Hot In Grow Tent? 

How To Cool A Grow Tent Without AC

Cannabis plants are relatively hardy, but the wrong conditions can lead to some seriously stunted growth and disappointing yields. Cannabis prefers different optimum temperatures throughout the growing stages, but as a general rule, avoid going above 85 degrees Fahrenheit. 

When you first plant your seeds, keep your plants at around 68 to 77 degrees Fahrenheit.

Younger plants in the vegetative stage prefer warmer temperatures. They should be around 70 to 85 degrees Fahrenheit.

During the flowering stage, lower temperatures are preferred. Aime for 65 to 80 degrees Fahrenheit.

How Do I Keep My Grow Tent Cool In A Hot Garage? 

Cannabis plants need a lot of light to grow healthy, but that doesn’t mean they need light the same times we do (Also check out What Is A Quantum Board LED Grow Light?). In a hot garage, try switching daytime to nighttime. Have your LED lights running during the cooler nights, and switch them off when the sun comes up.

You can combine this switching method with some other cooling options, such as ice and fans, to help lower the overall temperature of a hot garage.

How Do I Keep My Grow Room Cool In The Summer?

When the summer heat kicks in, you need to keep a close eye on the temperatures of your grow room.

If you tend to have hot days and cooler nights, consider using the grow lights overnight, and keeping the room dark during the day. And make sure you have LED lights installed.

The room needs to have good ventilation. If you have to keep doors and windows closed, use a fan and an extractor to keep the air cycling through.

Frequently Asked Questions

What Happens If My Grow Tent Is Too Hot?

High temperatures stress the plant, leading to early flowering, smaller flowers, smaller buds, and a lack of potency.

How Can I Make My Grow Room Cooler?

You can cool down a grow room with fans and ventilation, and switching to LED bulbs can also keep the temperatures low.


An overheated grow tent can slow down the growth of your cannabis plant, leading to disappointing yields. If you don’t have AC, try using an oscillating fan and improved ventilation to keep the heat down.

What cooling methods have worked for you?

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