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What To Do When Your Marijuana Grow Room Gets Too Hot Or Humid?

What To Do When Your Marijuana Grow Room Gets Too Hot Or Humid?

What to do when your marijuana grow room is very humid? The grow space will naturally be humid because the marijuana plants emanate moisture that collects in the garden space. To get rid of that moisture, the easiest thing you can do is ventilate the room and replace the moisture with drier air.

For gardens that are closed systems, a dehumidifier must be used. Dehumidifiers have cold tubing that will condense the moisture in the air and make it less humid. Of course, they do release heat and can make the grow space too hot if you’re not careful. To avoid overheating, just affix some air vent tubing to the dehumidifier’s exhaust so that the heat is pointed outside the grow space.

If the room is both hot and humid, an air conditioner could work toward removing the moisture while cooling the garden. Make sure to download my free marijuana grow bible at this link and learn how to create perfect conditions in your marijuana grow room.

Hot grow room

What to do when your marijuana room is too hot? There are plenty of ways to cool down an overheated grow room. See what suits you best:

-It can be ventilated to remove the heat.

-An air conditioner can replace the hot air with cool air.

-Prior to flowering, an air cooler that evaporates water to lower the temperature can be beneficial. These coolers won’t add too much moisture to the air and are ideal and extremely efficient during vegetative growth. They are, however, not good for plants in the flowering stage because they create too much moisture.

-If the temperature drops drastically at night, you could solve the heat issues by running the garden’s lights at night instead of the day.

-Hydroponically-grown plants can shift temperatures based on how hot or cold the water is. You can keep the plants cool even if it’s technically hot outside. If the room temperature is somewhere in the 80’s (27-30*C), try to keep the water temperature in the 60’s (15-20*C). Growers can install aquarium water coolers to keep the water cool automatically.

-Any heat producing equipment should be taken out of the grow room is at all possible (e.g. light ballasts and large pumps).

-Avoiding heat starts from the beginning. Take preventative measures to ensure that heat will not be an issue with your crop. Air- or water-cooled lights keep the lamp’s heat from entering the garden. A series of tubes takes the heat from the lamps to the outside without affecting the temperature in the grow room itself.

Download my free grow guide and order some high quality seeds at this link here. We ship seeds to the US, CA and many other countries. For any growing related question please visit the marijuana support page.


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Comment Section

14 thoughts on “What To Do When Your Marijuana Grow Room Gets Too Hot Or Humid?

By G A on 30 August 2015

I received some of Mr. Bergman's 'GOLD' seeds, germinated them, all sprouted and are growing. At 22 days since poking their little heads above ground they are about 8 inches tall with 8 sets of leaves. I think I should top now. Is that a good idea now?

By latewood on 2 September 2015

The simple answer is; Yes. However;

Whether or not you want to top at this point is a matter for discussion.

Are you topping for lack of headroom in your grow space? Or; Topping to produce more bud sites?

It is time to start the plants on a nutrient schedule. I would probably frow them to 12-18" tall before topping. 🙂

By Kevin on 27 November 2015

First week's of flowering, what nutrients do I need to get potent big buds. I have earth juice bloom but what do I need to use from week one throughout flowering

By latewood.ILGM on 27 November 2015

You have a bloom nutrient. That alone will do the job. You could research additives to the EJ Bloom. I would see what Earth juice offers, 1st.

By Iripplipps on 14 April 2016

My plants are 3 weeks old and are doing well. I'm now starting to increase nutrients accordingly. When is it time to remove large fan leaves?

By latewood.ILGM on 16 April 2016


You never want to remove big fan leaves. They are the heart and soul of the plant. If the plant has issues; it is the Fan leaves that provide the balance to keep the plant healthy. Fan leaves will fall off in mid to late flowering period, naturally indicating that the plant is finishing! 🙂

By Steph on 30 September 2016

What's the optimum temp & humidity for indoor plants?

By latewood.ILGM on 3 October 2016

Optimum temps are 70-80f and humidity 50-60% in veg, and 40% in bloom. I suggest you download and read our free Grow Bible, then join our support forum
Happy growing 🙂

By mark genanatti on 9 April 2017

so in veg no hotter than 60 degrees

By Robert Toth on 18 July 2017

I am a first time hydroponics grower, I thank you for the Grow bible. My infant plants look vary good, nice leaf production & root production. I use the H2O to grow 5Gal bubbler Bucket w/ Advanced Nutrients 2 part (part A 3-0-0, part B 1-2-6) food source. My concern is my nutrient base might be inefficient for marijuana. Do you have a better suggestion? I have spared no expense & I desire to get this right the first time. Thank You, Robert

By latewood.ILGM on 21 July 2017


After using An, then GH, then Dutchmaster, and Foxfarm, I did a grow with Roberts ilovegrowingmarijuana Flower power starter pack. This is the easiest nutrients I have used considering you do not need to add anything else and can yield 4-10 oz. per plant, depending on strain and grow methods (expertise)

Join us at the ILGM support forum, and we will make sure you are "right", the 1st time.

See you there, lw 🙂

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