How to Cool a Grow Tent: Most Exclusive Cooling Solutions EVER!

Lately, we’ve been publishing a number of articles that answer specific questions regarding grow space chilling. There are guides on high temperature controlling, cooling grow spaces with ice, and whatnot.

But what we eventually felt is, there should be a piece that touches everything on how to cool a grow tent, and the questions followed by. And when we say EVERYTHING, we mean it. It should be the one-stop article that every grower would be benefited from.

And we decided to do it right away!

It took a week to do the research, to collect every issue faced by growers regarding grow tent cooling, to provide the most real-time answers to every question found, and to wrap the whole thing up.

 finally, the best guide on grow tent cooling solution is live now.

So, grab a cup of coffee, and give yourself 10 minutes to read the whole article. We promise that every part of it will be helpful to you sooner or later.

Glide through the entire piece, and let’s meet at the end again.

Reasons for A Rise in Grow Room Temperature

If you’ve yet to build your grow space, that’s cool. But in case you already have one, then a high temperature might be troubling you badly. So, before proceeding further, take a look at the most possible reasons for it-

Improper Ventilation

Take a look at the outdoor garden or the local park. What’re the other things that mother nature is providing them apart from the sunlight? You’re right, it’s the natural air flow. Which is termed as Ventilation in case of indoor growing. Lack of proper ventilation comes with several discomforts for the plants. And a higher temperature is the #1 of them.

Too Many Heat Producers

Lights are the greatest heat source in a grow room. But there are items that emit heat that circulates around the space. Examples- Light Ballasts, Large Pumps, etc.

Not-so-Insulated Location of the Grow Tent

I’ve been a grower for past 2 years. And from the very beginning, I grew plants in my basement. Growing in such an insulated area helped me to get at least 5°F less temperature than the same setup planted anywhere in the house.

And when the plants get overheated from one or many of these reasons, that begin to show signs of stress. Which results in a low yield of flower or fruit. Go through the next sections of the article, if you’ve to know some real-time ways to beat the heat in your grow space-

7 Grow Room Cooling Solutions That Actually Work

Condition The Air with An Air Conditioner

Nothing can beat an air conditioner when it comes to cooling a confined space like your grow room. It not only cools the environment but also takes the heat away that’s generated from equipment like blowers, generators, pumps, ballasts etc.

Growers are likely to use ACs of various sizes. Sometimes, these are labeled in terms of BTU(8,000 BTU, 10,000 BTU, 12,000 BTU, 24,000 BTU, 36,000 BTU, 48,000 BTU), and sometimes on the weight(1 Ton, 2 Ton, 3 Ton, 4 Ton). We’ve got a complete guide on grow room cooling calculator that can help you pick the right size.

Take a note that, while many growers use portable AC units, and window AC units and so on, the best option is to use a ductless mini split system.

However, AC’s are likely to consume a lot of energy. So you can’t always be depended on an AC unit to carry all of the cooling tasks. For more cost-effective ways, keep reading rest of this article.

Take Care of The Ventilation

Ventilation or air exchange of a grow space is the most important environmental factor that directly affects its temperature. Lack of proper air flow will result in a constant increase in temperature, as the heat generated inside will just accumulate.

The next question popping up in your mind is- what it takes to have a proper ventilation?

Long story short- it means to have the same airflow that ‘mother nature’ would do if the plants were grown outside.

To have an optimal coolness for the ventilation system, do these-

First, Ensure a proper, and regulated air flow inside the grow space. To do the job, there are two kinds of fans available- Oscillating Fans and Extractor Fans. One is appointed to blow air above, under and around the plants. While the other fan cycles out old air and brings on new air from outside.

In both of the fans, there are variations in types, sizes, numbers, and position. Based on the size of grow space, a number of plants, and other environmental condition, you’ve chosen the best combination.

Second, maximize the effectiveness of the grow fans. Start with placing input ductwork in the coolest place nearby. Next on, invest some bucks after an automated controller that raises and lowers the fan speeds, based on the temperature.

Structurize The Grow Room

Number of Plants

An overcrowded tent is never ideal. Every tent has a maximum number of plants that it can house. Too many plants can cause many issues, the high temperature is one of them.

Using Smart Pots

To help plants to fight the heat stress, an ingenious idea is to house them on smart pots. These can aid surge evaporation, which decreases the chance of overheating, and keeps the plants sound by providing oxygen from the sides.

Another smart pot hack that helps grows tent to cool down is to use Coco air. Your plants will be more heat resistant to it. There are some other supplements that help fighting heat stress. 

In case, If you are interested to know about the procedure of grow room setup, My Garden Plant is the best place to go.

Optimize The Lights

Lights are the main culprit behind the dangerous heat spikes. There can be a few ways when lights will act more like heat sources rather than light sources. The ways are-

  • Lowering the lights when plants are mature.
  • Excessive heat generation from low-quality lights.
  • Lack of airflow between the lights and plant canopy.
  • Keeping the light on while it’s unnecessary(daytime).

To optimize the lights to lessen their heat impacts, here are few things that you can do-

Raise The Lights

To prevent the direct heat impacts of lights on your plants, raising the light by 8-10″ can be a temporary measure.

Install A Light Mover

Light sources at a constant place may create some hot spots and uneven illumination throughout the space. Try occupying a motorized mover. They transport the lights back and forth, or through a curved track. What it benefits is, the light distribution becomes more uniform across a broad area. Also, it reduces the number of hotspots and issues with canopy overgrowth. Most importantly, it helps in reducing the negative effects of high temperature on the plants.

Run Lights At Night

The ambient temperature is a few degrees cooler at night, comparing to the daytime. Growers, especially those living in a hot climate, should never do the mistake of running lights in the daytime. Because the temperature then is already a few degrees higher. Instead, run lights at night. It’s will keep the temperature under control. And maybe it won’t let the electricity bill be soar. So, you’re saving both energy and money in a way.

Use Air Cooled Lights

One great way to prevent lights from generating heat is to use air cooled lights. They can be connected to the duct lines in order to pass the hot air from the bulbs away. A proper insulation will boost up the process even more.If you want to move one step further, you can go for water cooled lights. They contain a water reservoir and water pump to conserve water. In a perfectly sealed grow tent, a water cooled light may deduce the essence of an air conditioning unit also.

Ensure Proper Ducting and Insulation

It had been found that each additional right-angle bend of the ducting will lower the performance of fans by 5%. And same happens if you have an improper ducting. Sealing every part of it, with an insurance of the least number of bends is what it takes to be awesome. Also, avoid as many right angles bend as possible.

Ducting is about insulating the airflow inside. But about the entire grow space?

Well, insulating the grow space is essential as well. But it’s equally important to place the entire grow tent in a place which’s not influenced by the warm weather outside. If you’re growing in a place where your growing area is not cordoned off, you’re about to face a frequent rise in temperature.

Here are some ‘dont’s’ when it comes to relocating the grow room-

  • Don’t locate it n a south-facing exterior wall.
  • Don’t place a grow room under a hot roof. Try basement or something similar.

Optimize Plants & Nutrient

This is not a direct solution to the cooling problem of your grow tent. But this is the savior when your plants are about to get toxic. And what is that?

A rise in temperature will cause the plant roots to intake more water due to over-transpiration. And while roots are doing that, they’re not taking more water only, but more nutrients too. With over-consumption of nutrients like boron, copper, and manganese, the chance of toxicity will get even higher.

Solution? Reducing nutrient concentration by about 20%-40% by adding pure water to it. Also, air circulation in the reservoir may give you a hand.

Keep Humidity Under Control

Another strong catalyst behind your grow room’s temperature is a low level of humidity. As you know, low humidity causes a rise in temperature. And vice versa.

To beat with a high temperature, increase the relative humidity of the grow space. That will help plants to do exhale water vapor through leaves, resulting in coolness.

Now, how much increment would be needed? Or how to keep your grow tent cool with that?

A fine rule of thumb is to keep the humidity 60% or more for young plants, and 40% or more for mature, flowering plants.

Products Used in A Grow Room Cooling System

Growing indoor is a made up system. So there is a product available on the market for every possible problem you may face. And when it comes to cooling, there are a few more.

Inline and Oscillating Fans

Every grower knows that it’s a must to have a fan to maintain temperature and ventilation. Even after knowing that, they make mistakes in finding the right type and size of grow fans. There are two types of fans for grow spaces- Oscillating One, and Inline one.

Oscillating fans do provide air circulation around the plants inside, where inline fans exhale hot air and intake fresh one. However, getting a fan with proper CFM value is important. Proper selection of power, a number of fans, placement, and orientation will decide that how effectively they can help you to prevent heat issues.

Here are some of our recommendations-

– Best Inline Fan:Apollo Horticulture 6” Inch 440 CFM

– Best Oscillating Fan(Wall Mount): Hurricane 16″ Wall Mount Fan

– Best Oscillating Fan(Standby): WestPointe HP 16″ Stand Fan 

Mini AC Units

As you know, three types of AC’s are there- Portable, Split and Window AC. While these three kinds vary from size, use, features, and of course price. If you’re using a grow tent of something like 2X4 or 5X5, a portable ac within budget will do. But when you’re growing in a larger space, mostly in grow rooms, split AC’s are the best options.

And about the third one, we don’t think that a window AC would be a cost-effective fit for a growing space. However, you can have a look at our in-depth discussion of different types of grow room AC’s.

For now, here are our best picks of AC units for growing room and tent

Midea Portable Conditioner12,000 BTU300 Sq.ft.See Price
Whynter ARC-14S14,000 BTU500 sq ftSee Price
LG LP0817WSR8,000 BTU150 sq ftSee Price


This unique piece of kit has become the one-stop solution for many growers when they have to control the grow space climate. It’s basically an air-con, combined with a CO2 feeder, dehumidifier, and air filter.

There are two types of them- The Split Type and The Water-cooled type. Growers are more likely to use the second one. The best part of its features is, it automatically does the cooling and dehumidifying job, based on the temperature and humidity of the space. And the worse part? It’s too expensive.

Here is the Opticlimate Pro 3, in case you’re interested.

Water Chillers

Chillers are with a mission of absorbing the extra heat that builds up in a growing space. There are both water-cooled and air-cooled chillers. Growers prefer water chillers in most cases, although they cost higher.

In a hydroponics water chiller, a water in the reservoir and a nutrient solution is the heart of the system. The mixture of water and nutrient actively works to cool the temperature down. Again, water chillers are for indoor hydroponics only.

Our recommended models-
– JBJ Aquarium Arctica Titanium Chiller
Hydrofarm Active Aqua Chiller

Evaporative Cooling Systems

The name sounds bulky, but the process that ECS’s follow is pretty simple. It includes a solution that can provide mists into the air, and the mist is meant to be vaporized. There is also a swamp cooler fan that blows air into a wet media. As a combined action, the evaporation takes place and the grow tent environment starts to cool down.

Here is the one that we recommend-
SPT SF-614P Evaporative Air Cooler

Ice Box

If you want to spend a minimum amount of money to keep a small grow tent cool, the best way to prepare an icebox yourself. The process is super easy and it costs less than any other products mentioned above. Here is our recommended DIY Grow room icebox tutorial.

These are the products that cool directly cool air to keep the temperature low. But there are some other products on the market, that don’t supply cool air themselves but works great to avoid heat generation. Here is a short list- 

  • Light Dimming Function.
  • Reflector Hood Lights.
  • Plant nutrients and supplements.
  • Smart Pots.

To Be Noted: Using all these products works to control the temperature in pretty much every grow spaces. But the problem occurs when you’re not sure about ‘How Big’ or ‘What Kind’ of product you should spend your bucks after. Because, based on the size of your grow tent, the type and power of each of these products vary a lot.  

Be sure about that, whenever you purchase a product to deal with the heat issue.

Check If You’re Making These 4 Mistakes Or Not-

  • Unequal Ducting and Exhaust Hole Dimension
  • Too Many Bends in Ducting
  • Running Lights @ Daytime
  • Too much space above the lights.

Summary Line

So, guys, that was all of the posts. In case you’ve gone through each part of it, take a bow, man. And please let me know if I’ve missed any of the points.


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