How To Cool Down A Grow Tent Without AC

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So, the water in the soil is evaporating too quickly, your pot plants are wilting, and the temperature is just way too high. Yeah, it’s a problem that many people face when growing weed in a grow tent.

You need to cool things down to the appropriate level, but how to cool down a grow tent without AC is something you need to know how to do to.

Well, there are indeed various ways of controlling the temperature in your grow room without an AC.  These methods include;

  • Using normal air fans.
  • Increasing ventilation.
  • Reducing grow light strength.
  • Using intake and outtake fans.
  • Use air or water cooled lighting .
  • Better insulation.
  • Running your operation at night.

Below we cover each in a lot more detail;

Best Ways Of Cooling Down A Grow Tent Without AC

Here we want to discuss seven of the best way to help cool down your grow tent without using an air conditioning system.

There are actually quite a few solutions, and most of them are pretty darn simple too.

1. Use An Air Fan

The first thing that you can do to help decrease the temperature in a grow room without an air condition system is to use a simple air fan.

Now, an air fan will help move air around, and the simple movement of air should help the air cool down in of itself. The movement of air does lead to cooling.

No, an air fan won’t do the trick on its own, especially if the grow tent is way too hot, but it is a good start indeed.

What you need to pay attention to here is that you get a fan that is energy efficient and runs cool.

If you have a fan in your grow tent that runs hot and uses a lot of electricity, then it might actually do the opposite of what you are planning, or in other words, it can actually heat things up, so be careful with this.

We have reviewed our favorite clip on fans on this article.

2. Create More Ventilation

Another thing that will definitely help cool down a grow tent or grow room, even without an AC, is to create more ventilation.

Now, this does not have to be powered ventilation, such as with ducts and an intake and outtake system.

You can simply leave the door to the grow tent open a bit, cut a hole somewhere, or just leave the vent holes open instead of covering them.

Let’s remember that heat travels upwards, so the best places to leave open are near the top of the grow tent.

If you have a grow tent with top located ventilation holes, be sure to keep them open, and keep the zipper of the door partially undone too.

This will allow heat to escape the grow tent, plus it will let new and cooler air in as well, which will also help control humidity, plus it will provide your plants with more oxygen too.

3. Reduce Grow Light Strength – LED Lights

One of the biggest producers of heat in a grow tent are your grow lights. If you have a large tent with lots of lights, powerful lights, they will definitely work to substantially heat your tent, probably past the point of being ideal.

What you need to know here is that some grow lights run really hot and produce a heck of a lot of heat, whereas there are others which barely produce heat at all.

So, the bottom line here is that to keep the temperature at an ideal level for marijuana growth, you might want to use LED lights.

LED lights tend to run significantly cooler than all other kinds, and it can go a long way in decreasing grow room temperature by a few degrees.

If you have large HPS, Halide, or other such grow lights, it’s probably why your grow tent is way too hot.

4. Intake & Outtake Fans

Something else you can do to cool down your grow tent without an actual air conditioning system is to use intake and outtake fans.

So, we did already talk about normal air fans, as well as increasing the amount of ventilation in your grow room, but this is taking it one step further.

Here, you can use intake fans in the bottom of your tent, connected to the bottom located ventilation holes to suck in new air.

This cool air should help cool things down a bit, plus provide some new oxygen for your pot plants as well.

At the same time, you also want to have an outtake fan located at the top of the grow tent.

This will help suck out hot air from the top, and heat rises, so this is exactly what you want.

It’s like a super efficient air fan and ventilation system, one step down from a bonified air conditioning unit.

What’s cool about outtake fans is that you can also attach a carbon filter to help reduce airborne contaminants and to control odors as well.

5. Air Or Water Cooled Lighting

The next way to help keep things cool in the grow room is by using lights that are either air or water cooled.

This is what you need to do if you want better lights than basic LED lights.

Sure, LED lights are fine, and they do run cool, but they don’t produce the highest quality buds or the best yields.

There are other types of grow lights that produce much bigger and better yields, but of course, they run hot.

The solution here is to invest in high quality grow lights that have an integrated cooling system.

Air cooled is usually the better way to go, as it’s cheaper and more reliable over the long run.

However, water cooled systems usually do a better job at cooling and controlling temperature, but they are much pricier and require a lot more maintenance.

So, in other words, it might be time to replace your grow lights in the tent.

6. Better Insulation

Alright, so just beware that this insulation point can go both ways. If you live in a really cool climate, then having more insulation in your grow tent will actually cause it to be warmer.

However, on the other hand, if you live in a hot climate and need to cool things down, insulating your grow tent to keep heat out can make a big difference no doubt.

7. Run Your Operation At Night

The final way which you can keep your grow tent cool, and to help cool things down without air conditioning, is to run the grow lights during the night.

Of course, night time is a lot cooler, so if you run your grow lights at night, the heat from the lights won’t combine with daytime heat, so it won’t cause temperatures to skyrocket.

Of course, if your pot plants are vegging, you may have your lights running all day and night, but if you are flowering your plants, or even vegging them with an 18/6 light schedule, doing your best to run them when it is dark and cool out will definitely help cool things down a bit.


The fact of the matter is that sure, an AC is undoubtedly the best way to cool a grow room. However, they also take up a lot of space, use a lot of energy, they are noisy, and you might just not want one.

Yet, as you can see, there are several good ways of keeping a grow tent cool without an AC. If you really need to, use a combination of all of the methods we have listed here for the best results.


My passion for the sticky icky started nearly a decade ago, and it all began when I first laid my eyes on the beauty that is the marijuana plant.

I cover all aspects of growing from equipment recommendations to plant health/care tips to help both new and experienced growers.