How to Minimize the Heat in Your Grow Tent? 2021 Updated
If there is the one thing just about every indoor cannabis grower struggles with, it’s heat.
During the summer months, the combination of hot weather, growing in a confined space, and heat generated from grow lights and other equipment drives temperatures far beyond what is healthy for marijuana plants.
If you want your plants to make it to harvest, you need to do something about the heat.
Luckily, there’s a lot you can do. Growers have been successfully dealing with heat problems for decades. And so can you.
During the summer months, the combination of hot weather, growing in a confined space, and heat generated from grow lights and other equipment drives temperatures far beyond what is healthy for marijuana plants.
If you want your plants to make it to harvest, you need to do something about the heat.
Luckily, there’s a lot you can do. Growers have been successfully dealing with heat problems for decades. And so can you.
How do I know that my grow tent is hot?
The simplest way to tell whether your marijuana grow tent is too hot is to use a high-quality thermometer and hydrometer.
Although you could get a sense for your grow tent’s temp by walking inside every day, the only way to accurately gauge temp and humidity is to monitor levels on these devices.
Beyond using a thermometer and hydrometer, there are a few other warning signs your grow room is getting too hot.
For instance, if you notice your cannabis plant’s leaves curving upwards, then you should think about reducing your grow tent’s heat levels.
Other warning signs of excessive heat include a “rotting” smell, dry soil, bud burn, and a slower-than-average flowering period.
Plants are like children. They respond best to a consistent environment. What constitutes the best growroom environment can vary from plant variety to plant variety, but will often conform to a temperature range of between 70 and 80°F for aerial growth, and around 66°F for root growth.
When plants become overheated, they begin to show signs of stress. Heat stress can result in spindly young plants and mature plants that fail to flower or fruit properly. Excessive heat also makes plants more susceptible to disease. Beat the heat with these 9 proven strategies to keep things cool in your growroom.
The simplest way to tell whether your marijuana grow tent is too hot is to use a high-quality thermometer and hydrometer.
Although you could get a sense for your grow tent’s temp by walking inside every day, the only way to accurately gauge temp and humidity is to monitor levels on these devices.
Beyond using a thermometer and hydrometer, there are a few other warning signs your grow room is getting too hot.
For instance, if you notice your cannabis plant’s leaves curving upwards, then you should think about reducing your grow tent’s heat levels.
Other warning signs of excessive heat include a “rotting” smell, dry soil, bud burn, and a slower-than-average flowering period.
Plants are like children. They respond best to a consistent environment. What constitutes the best growroom environment can vary from plant variety to plant variety, but will often conform to a temperature range of between 70 and 80°F for aerial growth, and around 66°F for root growth.
When plants become overheated, they begin to show signs of stress. Heat stress can result in spindly young plants and mature plants that fail to flower or fruit properly. Excessive heat also makes plants more susceptible to disease. Beat the heat with these 9 proven strategies to keep things cool in your growroom.
How to Minimize the Heat in Your Grow Tent?
Choose LED Grow Lights
Your choice of grow light has a major influence on the environment inside your grow tent. Most growers opt for either HID bulbs or LED lamps.
HID bulbs can be either HPS (high-pressure sodium) or MH (metal halide) lights. Growers who use HIDs typically use MH for the vegetative phase and HPS for flower. This has been the traditional approach to grow tent lighting.
But it’s no longer the preferred option. Now, even home growers are choosing LEDs over HIDs with increasing frequency.
While LED technology is still fairly new and comes with a somewhat higher initial investment, the benefits are many. They consume about half the energy of HIDs, high-quality LEDs last around 10-15 years, and they yield a better product.
They also emit significantly less heat.
It’s true that you will have to manage heat in a grow tent no matter what type of light you choose. But LED grow lights make the task much easier. You require far less supplemental cooling when you use LEDs.
Install a Quality Ventilation System
If you don’t have a ventilation system, you need one. If you have one, make sure it’s hooked up property and has enough power to meet your needs.
A ventilation system controls heat in a grow tent by expelling hot air and ushering cooler air in from outside the tent. A typical system includes an exhaust fan, ducting, and a carbon filter to neutralize plant-related smells.
The exhaust fan—also called an inline duct fan—is responsible for the exchange of air. It releases the hot air that would otherwise be trapped inside your tent and brings in fresh air from outside your grow space.
Ducting manages the directional flow of the hot, stagnant air your exhaust fan expels. It’s important that you route your duct out a window or into a hole in the ceiling leading towards the attic.
You don’t want to push that old air into the space surrounding your tent… otherwise, it all comes right back inside.
Your choice of grow light has a major influence on the environment inside your grow tent. Most growers opt for either HID bulbs or LED lamps.
HID bulbs can be either HPS (high-pressure sodium) or MH (metal halide) lights. Growers who use HIDs typically use MH for the vegetative phase and HPS for flower. This has been the traditional approach to grow tent lighting.
But it’s no longer the preferred option. Now, even home growers are choosing LEDs over HIDs with increasing frequency.
While LED technology is still fairly new and comes with a somewhat higher initial investment, the benefits are many. They consume about half the energy of HIDs, high-quality LEDs last around 10-15 years, and they yield a better product.
They also emit significantly less heat.
It’s true that you will have to manage heat in a grow tent no matter what type of light you choose. But LED grow lights make the task much easier. You require far less supplemental cooling when you use LEDs.
Install a Quality Ventilation System
If you don’t have a ventilation system, you need one. If you have one, make sure it’s hooked up property and has enough power to meet your needs.
A ventilation system controls heat in a grow tent by expelling hot air and ushering cooler air in from outside the tent. A typical system includes an exhaust fan, ducting, and a carbon filter to neutralize plant-related smells.
The exhaust fan—also called an inline duct fan—is responsible for the exchange of air. It releases the hot air that would otherwise be trapped inside your tent and brings in fresh air from outside your grow space.
Ducting manages the directional flow of the hot, stagnant air your exhaust fan expels. It’s important that you route your duct out a window or into a hole in the ceiling leading towards the attic.
You don’t want to push that old air into the space surrounding your tent… otherwise, it all comes right back inside.
Grow Room & Tent Air Conditioners
If high temperatures are wrecking your indoor garden, there is no better way to quickly bring the temperature down than an air conditioner.
You can easily place them either in the grow tent or some models allow you to have them outside the tent while ducting the cool air in.
For more information on air conditioners, read our guide on choosing and sizing the best one for your growing space.
If high temperatures are wrecking your indoor garden, there is no better way to quickly bring the temperature down than an air conditioner.
You can easily place them either in the grow tent or some models allow you to have them outside the tent while ducting the cool air in.
For more information on air conditioners, read our guide on choosing and sizing the best one for your growing space.
Add CO2
The addition of CO2 is proven to fatten up buds and boost marijuana yields. This heavy harvest technique is best suited to commercial grow ops and very popular with the more experienced grower.
Moreover, higher levels of CO2 allow for a higher temperature in the grow show and it is a way to capitalise on higher temps.
However, for the home grower probably sleeping in the bedroom next door, exercise caution and stick to a simple passive system rather than dabbling with CO2 tanks.
The addition of CO2 is proven to fatten up buds and boost marijuana yields. This heavy harvest technique is best suited to commercial grow ops and very popular with the more experienced grower.
Moreover, higher levels of CO2 allow for a higher temperature in the grow show and it is a way to capitalise on higher temps.
However, for the home grower probably sleeping in the bedroom next door, exercise caution and stick to a simple passive system rather than dabbling with CO2 tanks.
Look After Your Nutrients
When mixing nutrient solutions, especially in larger volumes and storing it in a water tank over several days, it's vitally important that the temperature should be kept between 18-21°C. If the temperature drops too low, the plants' roots will go into shock, slow down absorption and impede growth. Whereas too warm, the oxygen levels will decrease, plant growth will again slow, but also make them more susceptible to diseases like Pythium, aka Root Rot.
To combat this and keep pre-mixed nutrient solutions at the perfect temperature, a Water Heater should be used. Being fully submersible, they sit in the water tank and keep the solution at the pre-set temperature at all times.
Storing the nutrients effectively is imperative as poor storage can lead to damaged nutrients. If storage is too cold, the dissolved salts that make up your nutrients may crystallise and become solid. In this form, they are no longer part of the nutrient solution and remain unavailable to your plants.
In order to prevent this, make sure to store nutrients in a cool, dark place, out of direct sunlight, where temperatures sit between 10 Degrees and 19 Degrees. As a rule, never allow your nutrients to be stored at temperatures below 5 Degrees.
Top Tip: Keep an eye on your nutrient temperatures by using a waterproof Bath Thermometer that can permanently sit in the solution and give an accurate reading.
When mixing nutrient solutions, especially in larger volumes and storing it in a water tank over several days, it's vitally important that the temperature should be kept between 18-21°C. If the temperature drops too low, the plants' roots will go into shock, slow down absorption and impede growth. Whereas too warm, the oxygen levels will decrease, plant growth will again slow, but also make them more susceptible to diseases like Pythium, aka Root Rot.
To combat this and keep pre-mixed nutrient solutions at the perfect temperature, a Water Heater should be used. Being fully submersible, they sit in the water tank and keep the solution at the pre-set temperature at all times.
Storing the nutrients effectively is imperative as poor storage can lead to damaged nutrients. If storage is too cold, the dissolved salts that make up your nutrients may crystallise and become solid. In this form, they are no longer part of the nutrient solution and remain unavailable to your plants.
In order to prevent this, make sure to store nutrients in a cool, dark place, out of direct sunlight, where temperatures sit between 10 Degrees and 19 Degrees. As a rule, never allow your nutrients to be stored at temperatures below 5 Degrees.
Top Tip: Keep an eye on your nutrient temperatures by using a waterproof Bath Thermometer that can permanently sit in the solution and give an accurate reading.
Keep Those Ballasts Outside The Grow Tent
It’s advisable to mount your ballasts, control boards and other electrical contacts outside of the grow tent on a wall. Good housekeeping when it comes to electronics won’t just shave a few degrees off temps it might just save your life.
All ballasts and grow equipment build up heat and keeping them outside of the grow area and off the floor is the smart setup.
It’s advisable to mount your ballasts, control boards and other electrical contacts outside of the grow tent on a wall. Good housekeeping when it comes to electronics won’t just shave a few degrees off temps it might just save your life.
All ballasts and grow equipment build up heat and keeping them outside of the grow area and off the floor is the smart setup.
Final thoughts
If you want your crop to grow healthily, you must ventilate your grow room adequately, as proper air circulation can help you to regulate humidity, temperature and CO2 levels within your grow room. You must set up an air extractor fan system that can provide both passive and active ways to ensure entry of air into your grow room.
You must find the optimal CO2 level for your plant and rely on a carbon filtration system to help avoid odors. You can use ducts to connect your fans and filters. You must also regulate the humidity level within the grow tent, as it is crucial to the health of your crop. Too much or little humidity can both be harmful.
You must also regulate the temperature inside your grow area. You must especially ensure that the canopy (leaf) level temperature is roughly equal to the ambient (room) temperature. Thus, your success as an indoor gardener could depend on how well you ventilate your grow room. Also, a best grow lights for indoor plants can help you more.
If you want your crop to grow healthily, you must ventilate your grow room adequately, as proper air circulation can help you to regulate humidity, temperature and CO2 levels within your grow room. You must set up an air extractor fan system that can provide both passive and active ways to ensure entry of air into your grow room.
You must find the optimal CO2 level for your plant and rely on a carbon filtration system to help avoid odors. You can use ducts to connect your fans and filters. You must also regulate the humidity level within the grow tent, as it is crucial to the health of your crop. Too much or little humidity can both be harmful.
You must also regulate the temperature inside your grow area. You must especially ensure that the canopy (leaf) level temperature is roughly equal to the ambient (room) temperature. Thus, your success as an indoor gardener could depend on how well you ventilate your grow room. Also, a best grow lights for indoor plants can help you more.
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