15 Ways How to lower temp in grow tent?

You are here, which means you must be suffering from the increased temperature inside your grow room. How to lower temp in grow tent- if this question scares you, then relax! We at 420expertadviser have come up with several solutions through which you can save your plants from heat stress.

Stay with us till the end!

I recommend you try #7, Using Dry Ice, mentioned in this article. It’s a DIY and very easy method. Learn how to do it.

Growing cannabis plants indoors is fun. But let me admit it is much more challenging, though. When growing cannabis outside, a grower has to face several weather conditions; on the other hand, growing weed inside also has problems like a proper light schedule and finding the best grow lights, and after that dealing with high temperatures.

The good news is that you can reduce the heat generated by the grow lights. And here you will find everything.

First of all, let me tell you about the right temperature inside your grow space and what happens to your plants during heat stress.

Rising temperature in your grow tent


Why temp rises inside a grow tent?

Certainly, our primary heat source – the grow lights we are using are responsible for the hot air traveling inside the tent.

All the grow lights, whether HPS, HID or MH or even LED grow lights, all emit excessive heat along with the light. Our plants are kept under the heaters inside any grow tent. The plants cool themselves by throwing water in the air through their stomata.

But when the temp rises, especially in summer, the entire tent starts suffering from more heat, and plants won’t be able to cool down. Hence, the temperature rises more!

What should be the right temperature inside the grow tent?

Every grower faces the issue of increasing heat at some point in his journey of growing marijuana. If you are a new grower and trying your hands on growing cannabis plants indoors, then you must know about the ideal temperature of the grow space.

Well, according to the most accepted generalized temperature is 70-80°F or 21.1-26.6°C. This temperature is the ideal temperature of the grow tent. Here, you must understand that the whole growing space should have a uniform temperature.

However, in a few cases, temp may get higher and still, plants do well.

What are the symptoms that your plants are facing heat stress?

Usually, it is recommended to keep a thermometer inside the tent. But you don’t have them also, you can identify that your plants are facing excess heat as they would show various signs.

These symptoms include:

  • Plant leaves become pale, burnt.
  • Plants stop growing like their height stops increasing.
  • Either the fruiting stage reaches early or it doesn’t come.
  • Also, if you see your flowers have not grown properly or fruits are not as expected, then it is easy to understand that the light is too hot for your plants.

Not to mention how badly the temperature fluctuations affect photosynthesis, germination, flowering, fruiting stages, and plant yields.

As of now, you must have understood the cons of excess hot temperatures.

Let’s now discuss how to suppress the excess heat inside your grow room.

Methods to Combat Heat inside the Grow room

After discussing all the problems of the hot air inside the grow room, Finally, we can discuss the solutions.

There are various easy ways to cool down your grow tent. Some of them don’t need to invest the money.

1) Using an Oscillating fan inside the grow tent:

This is probably the easiest way to maintain good air circulation inside the grow room. Adding oscillation fans helps in moving air and thus help in optimum airflow.

Air circulation helps distribute the heat uniformly and stagnant air moves all around the tent to disperse heat.

Using Oscillating fans have several benefits:

  • These fans don’t take up much space.
  • They disperse heat uniformly and help higher temperatures lower down.
  • You can control fan speed manually anytime as you need.
  • Installing Oscillating fans is not a costly deal.

If using these fans would help you in lowering the temperature to a few degrees.

2) Use air conditioner in grow room:

Indeed, the Air conditioner is the fastest way to keep your grow room cool. It is quite an effective way, though. Yet using an air conditioner inside requires space inside grow tent. Also. Using these would result in adding more burden to your pocket.

That’s why I recommend that if you have ample grow space and you can go easy with the heavy electric bills, then only use the air conditioner.

3) Using Swamp cooler:

A swamp cooler is an excellent option if you are looking to increase the humidity levels of the tent. These coolers are very different from the traditional coolers because they use the evaporation of water to cool air.

Interestingly, using a swamp cooler could lower the temperature by 100.

These coolers are very effective and consume less electricity. Hence, using a swamp cooler is a more cost-effective option than air conditioning.

However, don’t use these coolers if the humidity level in the grow tent is already high.

4) Using exhaust fan:

An exhaust fan helps to keep throwing the blowing air outside the window. Hence keeps airflow properly. Continuously moving the air would not let increase heat stress. Exhaust fans should be placed on the outside window.

The proper exhaust system doesn’t let the outside air heat much and thus, the air around the grow room remains cool. The intake air thus remains cool.

Again you don’t need to invest a large sum of money in fitting the exhaust fan.

5) By increasing CO2 levels:

Adding a bag of CO2 would be a great relief from high temperatures. This is a proven and famous technique among most growers,

The benefits include-

  • Adding CO2 is easy, you just need to put a bag inside the grow room.
  • It is not only helpful in combating high temperatures but also increase you yield by many folds.
  • You will find your buds are getting heavier and healthier.

In contrast, using excessive Co2 could be harmful to your health if you are growing in your home. So, stay cautious.

Buy your CO2 Pack from here.

6) Consider changing your grow light to LED grow light:

Replacing your traditional HPS/ HID or Metal Halide lamps with a good quality LED grow light can dramatically resolve your heat issues.

I know what you will say, that all lamps emit heat. Yes, that’s true.

Heat rises whatever lamp we use. But LED grow lights emits less heat output than any other lamps. Also, if you consider lights with proper veg and bloom modes, then you can save your plants from having too much heat stress.

Remember, too much light is equally harmful, and by using LED grow lights, you can have control of both heat and light.

  • The benefits of using LED lights are many:
  • These lights require low maintenance.
  • Less energy consumption
  • Better light spectrum
  • Less danger of high temperatures.
  • Plants have healthy growing environment

So, what are you waiting for? Consider replacing now!

7) Creative way to decrease heat output by using Dry Ice:

If you don’t want to spend money on any CO2 yet expect maximum yield from your plants by keeping them safe from heat damage, then It’s time to show your creativity.

Take a thermocol box of any shape and size.

  1. Fill it with dry ice or homemade salted ice.
  2. Now seal it completely.
  3. Just make a hole in your lid of the box.
  4. Adjust your oscillating fan in a way that it faces towards the box.
  5. Now the heavy cool air would help in maintaining the temp of the grow tent.

There are several advantages of this technique:

  • It is Easy and fun to create such box.
  • It is almost a no money investment technique.
  • Plants will thrive in the cool CO2 levels
  • Would give you a better and maximum yield

If you don’t want to make such a box, you can place a bucket filled with ice or water.

8) Using a Dimmable Ballast or reducing the lights:

In scorching summers when high temperatures is a problem for every grower, considering using dimmable ballast would help.

If you are using LED grow lights with the dimmable option then you can put off some light resources by using them or you can decrease their intensity.

Even if you are using HPS or any other lamp, then also you can add a dimmable ballast to help you with the heat problems.

Or, you can manually turn off some light resources to cool the warm air inside your grow room.

This would surely help, but many indoor gardeners don’t recommend using this technique as plants will not get adequate light and thus will not flourish well.

But we say instead of losing your whole crop to heat, it’s better to save the half. Consider hanging them outside the grow space.

9) It’s time to reset your light schedule: Run lights at night

Marijuana in night

Surprised! But this technique works!

We all know that in summers, the daytime temps are crazily high, and using lights in the daytime would add on the heat inside the grow tent.

Fortunately, many plants need 12/ 12 lights schedule. Thus, if you run lights at night or turn them on in the late evening, you will still have ample lighting hours left. There is a massive difference between the day and night temperatures. And we can take advantage of that.

In night, the heat won’t rise due to environmental factors and here’s where we can win! Just make sure that there shouldn’t be any light leak else, your amount of the maximum yield would be affected.

I highly recommend using this method as it doesn’t need anything more from you!

10) Increase Humidity levels:

By increasing the relative humidity level, you can decrease the heat inside your grow room. Science says that when there is an increase in the heat levels inside a limited area, the relative humidity decreases.

Further such conditions lead to drying up the plants, and your whole hard work will go wasted. By using a good humidifier, you can get rid of the excess heat.

If you notice your humidity level is decreasing by 50-60% in the vegetative state then don’t delay and buy a good quality humidifier.

11) Move your grow tent to cooler place:

Try relocating your grow tent to a cool place.

Hey! I am not saying that you go to the mountains with your grow tent.

Everyone has some area in one’s house that is relatively cooler than the other parts of your house. These may be your basement or a place near a window.

This way, your plants cool themselves by adapting the natural insulation. You can place them near air vents too.

12) Add Micronutrients:

As the heat rises inside your indoor garden, plants need more water to combat heat through TranTranspirationus, the plants start taking more water from their roots. This way, they absorb more nutrients as well.

In such cases, the lack of nutrients in the soil would directly affect the maximum yield.

There is a solution!

You can add micronutrients like silica in potassium silicate to add to the plant health. So that plant can fight the increased levels of heat inside. So it is better to use it as a foliar spray.

13) Dilute the Nutrient Solution:

As I have mentioned, to perform tranTranspirationants are used to suck the nutrients more than they need from the soil. This practice ends up in increasing toxicity in the plants.

Therefore many experienced growers recommend using the low concentrated nutrient solution to cycle air and better circulation of the dissolved oxygen.

14) Choose Heat Resistant Strains to grow:

If you are a new grower and growing cannabis during summers, you must consider some heat resistant strains for growing.

These strains can live well in high heat and still result in high yields. So, without taking much effort, you will have a happy growing experience.

15) Make a Good Ducting inside your grow room:

You must take care of the Ducting inside you grow tents. Believe it or not but a good and clear ducting can maintain an adequate temperature while twisted or bents in ducts will lower the efficiency of your intake fan or oscillating fans.

Make sure that the duct should be firm enough else it will again be a reason for the heat rise inside the grow tent.

Honestly, I have told you about all I know about lowering the temperature in a grow tent. If your queries persist, then have a look at FAQs.

FAQs about How to lower temperature in your grow tent:

Q1. Will increasing humidity levels will always solve our heating problems in the growing tents?

Ans: No, Increasing humidity levels can lead to more problems. You can increase humidity to a certain level but stay aware as an increase in humidity is a welcoming sign to moulds, pests and diseases.

Q2. Is it possible that my plants will recover from the heat stress they’ve been through?

Ans: Unfortunately, no. There is no way your plants will recover. But don’t give up and try again! But this time with full preparation.

Wrapping Up:

While keeping all things together I must say that we have several options to answer how to lower temp inside the grow tent. But, no method will give you a perfect solution.

However, these methods will certainly help to some extent. I’ve put the easiest possible solutions here. Try any.

Hopefully, I could have helped you in some way.

“Nurture your mind every day, by looking at the weed you’re growing. Believe me, if you understand weed, you get everything right.”

Christopher Andrews
I am Christopher Andrew, the owner of 420 Expert Adviser. I have been in cannabis cultivation for more than ten years, and I'm sharing my experience with you guys using this blog!

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