How to Reduce Heat Inside a Grow Tent

How to Reduce Heat Inside a Grow Tent

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Managing the ideal temperature for your cannabis plants can be a difficult task, when beginning to work in a new environment. Controlling the temperature inside a grow tent can be even harder, due to restricted airflow. Managing the heat levels can prove challenging, which is why we have written a guide to help you with the process.

Are High Temperatures Bad for Cannabis Plants?

If you are growing marijuana in an environment with high temperatures, or in an area where heat is unable to dissipate, the ambient temperatures may be much higher than the ~70 degrees Fahrenheit that your plants find comfortable, and lead to heat stress. An increased temperature can lead to slow growth, reduced harvest, and even eventual death of your cannabis plants. Heat is especially a concern during the flowering phase of the cannabis plants or for those who are growing hydroponically, where the roots are exposed (as opposed to being protected by a pot and layer of dirt). Fortunately there are a number of techniques, and supplements which can be used to control temperatures, and reduce heat damage to your cannabis plants.

Take a look at these simple steps to start reducing the heat temperatures inside of your growing area.

Using Oscillating Fans Inside Grow Tents

While fans will not eliminate the heat inside of your grow tent, it will help you to circulate the air. This is important, because you will traditionally want to keep your plants as close to the light as possible, where the most heat is being generated. The use of an oscillating fan can be used to disperse the heat created by your lights, and cool the plants.

oscillating fan in grow tent

Ceiling or Floor Vent for Grow Tent Exhaust?

Choosing whether to install your exhaust fan in the ceiling vent of your grow tent can make a tremendous difference, because of the way heat rises. The ceiling vent will allow the hot air to be sucked out, while passively pulling air from the floor vent, where the air is cooler. This simple configuration change can make a huge difference in the amount of effort required to control the temperatures inside your tent.

Use a Cooling Humidifier

The usage of a humidifier with a cooling effect, such as Vick's Cool Mist Ultrasonic inside your grow tent will help to reduce temperatures even further, while increasing the humidity to appropriate levels. However, you will want to be careful not to let the humidity get too high - which can inadvertently increase temperatures. For vegetative marijuana plants, a humidity level of around 40% is considered ideal - whereas seedlings will benefit from much higher humidity levels.

Use Buckets of Water, or Ice

Strategically placing buckets of water throughout your growing area will both help to increase humidity levels, and reduce the heat inside of your grow tent. Ideally the buckets should be filled with cold water - and you can even use ice, or frozen water bottles. The bucket of water will act as a heat-sink, and absorb the heat inside of your tent.

This technique compliments the usage of oscillating fans inside of your grow tent. By placing the buckets of water in front of the fan, the air being circulated will cooled by the bucket of water, and reduce temperatures throughout the grow room.

Control the Temperature Outside of the Grow Tent

The temperature inside of your grow tent will naturally be a few degrees higher than the ambient temperature outside. For this reason, you should always look to improve airflow in the surrounding areas - ensuring all of the heat generated by your grow tent is dispersed. For this reason, it is ideal to connect your exhaust fan directly to an outside window, preventing any heat build up from occurring near the growing area. The usage of even more oscillating fans, or air conditioning can also help to control temperatures outside of the grow tent.

exhaust system connected to the window

Optimize your Marijuana's Day and Night Cycle

Many growers will also choose to run their lights for a full 24 hour period, instead of the tradition 16 hours of light, followed by 8 hours of darkness. In running your light for a full 24 hours, you will be increasing the amount of power required and overall heat output by 30%. For many grows this may not be a huge concern, however it is important to realize the diminishing returns associated with this. In other words, your plants won't grow 30% faster than if they were provided only 18 hours of light.

Keeping your lights on for a full 24 hours will increase the period of time that your fans and humidifiers are operating promoting wear and tear as well as raising overall costs of electricity. Temperatures are typically the highest during the daylight hours. In order to help control temperatures, you can configure your plant's day and night cycle so that the light is only on during the night, when it is coolest. The added benefit of this technique, is that your electrical bills will also be reduced because of the lower power costs during non-peak hours.

lighting timer

Supplements to Protect Against Heat Stress

Surprisingly, a number of supplements are very effective for reducing the negative impact of high temperatures by helping your plants to handle heat stress. These supplements should be used as a last resort, in order to keep the number of moving parts as low as possible and reduce undue complexities with your garden. However, if you have tried all of the techniques above, and are still experiencing high temperatures inside of your grow tent, these supplements may be what you need to prevent further damage to your plants.

Silica for Cannabis Plants (Potassium Silicate)

Helpful for a number of different environmental factors that your plants will prefer to avoid, Silica supplementation can help your plants to deal with the stress associated with higher temperatures. This will allow your garden to flourish at above average temperatures and without the negative impacts, due to increased resistant to stress. Supplementing your cannabis plants with silica also have a number of other in-directs benefits, such as a mild corrosion to the leaves - which actually make it less desirable to pests (if you were growing outdoors). We encourage you to learn more about the many benefits silica could provide to your garden.

Use Supplements for Root Health

If you are growing hydroponically, the roots of your cannabis plants will be exposed and much more vulnerable to higher temperatures. When the temperatures are at uncomfortable levels, the health of the roots will begin to deteriorate. This will become visually noticeable, and if you touch the roots - they will feel like they are covered in slime. The application of a supplement meant for root health can drastically impact the vitality of your plant's roots, and bring them back to health.

Heat Resistant Strains

Believe it or not, some types of cannabis will actually be more tolerant to heat and can survive higher temperatures. Typically, the strains which favor higher temperatures tend to be Sativa - with this gene appearing in many popular breeds of marijuana. Choosing one of these strains can considered the last option, for users who have not been able to control the temperatures inside of their grow tent.