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.

Too humid marijuana grow room
Humidity too high

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.

Heat stress curling marijuana leaves
Heat stress curling marijuana leaves

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.

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    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:

    Marijuana leaves burned
    Marijuana leaves burned
    • 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 during 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.

    Also read Ideal temperature for marijuana plants

    • Any heat-producing equipment should be taken out of the grow room if 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. 

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    For any growing related questions please visit the marijuana support page.

    Robert

    Avatar for Robert Bergman

    Robert Bergman

    Robert Bergman is an Amsterdam-based marijuana grow expert who has years of experience from small grows to massive operations. His passion for growing led him to develop his own Gold Leaf strain. Now, Robert is dedicated to sharing his knowledge with the world.... [Read full bio]

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      27 comments on “What To Do When Your Marijuana Grow Room Gets Too Hot Or Humid?”

      1. Im Growing strawberry cough in a grow tent i kept it in Veggie stage for 11 weeks and turned light to 12/12 last week but still not seeing signs of flowering, How many weeks until I see the first stage of flower?

        Reply
        • Hi Scott,

          Thanks for your comment. You should see flowers forming within about a week. If you are not even seeing preflowers, make sure to check for any light leaks as this could be keeping your plant from flowering.

          I hope this helps!
          Alex,
          ILGM

          Reply
      2. Just had a look at your site quickly, appreciate everything you do. Will get back to it soon. Thanks bro. Well done. Wal. From down Under.

        Reply
      3. My harlequin strain is curling very strangely the Bergman gold is fine. Plants are 10inches high. Nice color.

        Reply
      4. Hi all,
        I have a particularly difficult climate where i am. i have a grow room with 3 white widow plants, after almost 3 months I have changed from hd to cfl and 12/12, as my room easily gets to 38deg c. i have introduced an air conditioner to cool, i have a carbon filter fan to exhaust heat/ smell but am still struggling to keep temps low. CO2 is 400-600 humidity below 40%.
        is there anything else i can do and what can i expect in the flowering stage.

        Reply
        • Hi all,
          I have a particularly difficult climate where i am. i have a grow room with 3 white widow plants, after almost 3 months I have changed from hd to cfl and 12/12, as my room easily gets to 38deg c. i have introduced an air conditioner to cool, i have a carbon filter fan to exhaust heat/ smell but am still struggling to keep temps low. CO2 is 400-600 humidity below 40%.
          is there anything else i can do and what can i expect in the flowering stage.
          OK, my room is far too hot for flowering, have changed to led’s and the temp is coming down. its hard to cool a 2M x 2.4M x 2.5M room with outside temps 38-40deg C. Air con still on 17deg C

          Reply
          • Join us here: support.ilovegrowingmarijuana.com so we can go back and forth with you in order to attempt to help you out. We cannot do an aggressive Q & A here in the blog. I do not see how with an AC, you cannot get temps in line. See you in the forum. tag: @latewood to find me there and please be patient. Lots going on. 🙂 Staff and educated members will probably help you some before I get there. Peace

      5. 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

        Reply
        • Robert,

          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 🙂

          Reply
      6. 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 🙂

        Reply
      7. Iripplipps,

        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! 🙂

        Reply
      8. 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?

        Reply
      9. 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.

        Reply
      10. 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

        Reply
      11. 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. 🙂

        Reply
      12. 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?

        Reply
        • The picture above on the right where the text says “curling leaves”. It doesnt mention anywhere what that is a symptom of. I’m in the need of advice regarding that one, help is appreciated.
          Thanks!

          Reply
      13. […] When it comes to temperature, cannabis plants like it hot, but there is a point at which it can become too hot. Anything over 80 degrees Fahrenheit is likely to be less than beneficial for most varieties. If your grow room is too hot, you can use air conditioners to help cool it down. Alternatively, you can cycle cool water through the root systems to allow the plant to cool itself. Read more on what do to when your marijuana grow room gets too hot or humid. […]

        Reply
        • Bottom leaves are stating to turn purple is a dry out white widow 3 weeks old what causes this and how do I fix it?

          Reply
          • Probably phosphorus-deficiency. Check the amount of “P” in your nutrients, if it has enough then your pH might be off (if you’re new to this, pH is often the cause of problems).
            As a tip for next time, just google “cannabis purple leaves” 😉
            Peace!