How hot is TOO hot? (grow tent temps)

Discussion in 'Grow Room Design/Setup' started by Nomadik, Aug 4, 2017.

  1. Hello all;

    I recently got into growing, after being gifted a bunch of what I told were purple kush seeds. I have never grown anything before, I don't smoke pot, I'm not a seller, I'm just... curious. So, I decided to learn.

    Since the end of April, I have been vegging 3 plants outdoors, just growing them on the deck. 2 of the three seem fairly average, but the third is a BEAST. It grew taller, faster, thicker and fuller than the other two, with stalks that are like metal rods. When I started supercropping, it took pliers to crush the fibers enough to bend them, and the thing has been sporting 11 point leaves since the 4th node.

    Anyways, 2 days ago, I bought a 5x5 heavy duty grow tent and set it up inside an old weedshed, since the shed had a concrete floor and was fairly cool inside - about 5 degrees cooler inside than out - and because the shed served to hide the tent.

    So, I'm all set up, with my lights (LED's, because i was really worried about heat), a fan, a really high quality 400 cfm fan and a carbon filter, which vents to outside the shed, and draws it's intake air from inside of the shed. (both of the intakes are via ducting that bends 180 degrees twice, to keep light from leaking into the tent through the ducting) I just finished 36 hours of dark (though, the tent did get opened at night and there was some flashlights and setup stuff involved before I learned anything about the hazards of light leaks. oops!)

    So, my question is, how hot is too hot for inside the tent? Right now, the Island I live on is undergoing a massive heat wave, with temperatures approaching 104 degrees at the peak of day. (40C) No matter how hard I try, I can't get the tent temperature to get any lower during the day than 95, give or take a degree. (35). Also, I can't get the humidity to come up above 35%. Putting in an air conditioner isn't an option, and the best I can do for the humidity is spray the tent with a mister several times a day during the light hours. I'm thinking of soaking an entire tray of rockwool in water and leaving it in the tent to try to bring up the humidity a bit, but not sure if that will work or not.

    Anyways. Right now, it's HOT here, with forest fires burning out of control in every direction, smoke so thick you have to chew the air before you inhale, and windy like you wouldn't believe. It's just SUPER hot, with no end in sight, and I can't get my tent to where I want it - about 84 degrees. (29C). I wanted to do the light on cycle during the day to keep the lights from adding to the heat in the tent, but my wife pointed out that plants like cool at night, and having lights on at night and off during the day wouldn't give much heat relief during the dark cycle. And, I want to avoid having the lights on at night because if I need to open the tent to water, trim, maintenance, etc, I didn't want a big purple halo around the yard, as it's a bit of a heat score.. (I live in a very urban sprawl)

    The plants themselves seem to be fine. Healthy, no wilting, the tops are all starting to shift in color to that pale green/yellow indicating flowering is starting, holding water ok (IE, not drying out right after watering) and are growing and stretching. I'm just concerned with the heat and low humidity. Is 95 (35C) going to stress them to the point of them going hermie on me? As a first time grower, I am learning a lot, but still a little bit of a helicopter parent!)

    Relative info: Plants all came from unknown seeds, given to me by a friend. The 2 average ones were germinated with a paper towel and grown indoors for a month, then moved outdoors, the "beast" was germinated in soil, and grown outdoors since before it popped. It's the one with giant 11 point leaves and seems bulletproof.

    I live in the Pacific Northwest, 7B, 8A hardiness zone,

    Thanks for any tips!

    Attached Files:

  2. Your plants will tell you when it's too hot. They tell you everything in their own way and, in time, you will understand their language. Personally, I don't feel comfortable above mid 80's in the flower cycle. The temp of environment plays a big role in the growth, or not, of the plant. I would go back to natural sunlight though..if that's an option because you'll never get the yield or growth under artificial light that you get from the sun. As far as being worried about the plant outside and a heat wave, as long as you keep it watered and taken care of, I doubt it would suffer much. They're weeds and much hardier than you would believe. But light is the most important element of growing period and each plant you flower needs the same strong high quality light...more plants going, more lights needed indoor. LEDs offer sparse coverage normally because of small bodied fixture and no reflectivity in fixtures. But you'll figure it out though. Just part of the learning curve. Best of luck.
  3. I grow inside of a very small dual tent all year round when summer comes with a 600 hps in a 2x2 it gets pretty heated in there. The only way I can over come the heat some summers is adding co2.
    I did learn in the first year to not run my lights during the day no matter what the night time temperatures are. Humidity is a great help high as you can get in veg without actually having it dripping from your plants or laying around. I've used dwc bubble bucket minus the net pot to raise it before. For bloom I would leave it without supplimentation.

    Sent from my SAMSUNG-SM-G870A using Tapatalk
  4. I would dearly love to go back to just growing outside in the sun. I'd kill to be able to just get some autoflower seeds and stick them in the back yard and grow to the end, but I felt I was forced to move to a tent so I could control the odor. Unfortunately, I live smack in the middle of an urban area, and while the neighbors on once side don't care (they grow their own too, and have a greenhouse full of various strains) the woman on the other side of me is an uber-religious bible thumping ultra conservative that would report me in a heartbeat. She's a little crazy, and a little fundamentalist. :/ If she got even a whiff, she'd be screaming over the fence at me. lol.

    But, I dream of one day being able to grow freely, when I finally buy an acreage. :D
  5. My temps were hovering around 81-88. This made my first grow have airy and fluffy buds. They did not dense up. Now I have an auto pounder growing lovely with temps consist at 77-79 which is the perfect range. I had to open up the flaps on the sides of the tent to create passive air flow.
  6. See, I had my tent vents open, on both sides of the tent. But, I freaked out a little bit after reading that even the tiniest light leak can cause hermies, and since my tent is in a shed with about a billion holes chewed in it, when the sun comes up at 5 am (the lights don't come on until 10 am) I was getting substantial light leaking through those vents for 5 hours before the lights come on. So, I covered the vent and put in aluminium ducting that has a 180 degree turn in it to keep light out. So. It seems like solving one problem just created another three. Lol.

    I just went out and checked the temps. It's not quite dark yet, but the sun set about a half hour ago, and it's 28 degrees Celsius in the tent right now. :)
  7. I find for my setup with the pink kush strain that 79-82F is the sweet spot. any higher and it subtly starts throwing big hints
  8. Mid 70s is best. Above mid 80s and you're gonna get fluffy larfy buds.
  9. mmk makes sense. last grow was 82f albeit 2 weeks premature it was fluffy
  10. If you run the lights at night instead of during the day it helps with the temps.
  11. So, it's starting to cool off a little bit.. yesterday, the peak temp was 87 (31c), with humidity at 50% overnight, the tent went down to about 69.8 (21c) or so. The rest of the week is calling for the same temps as yesterday, so I'm hoping I'm right on the outside edge of tolerances.

    Btw, burnpile, I can't really run the lights at night.. they're LEDs anyways, so they're not making any really appreciable heat. :/
  12. You know what I did when I was having heat issues about a month ago? I was opening up the tents at night. And I put a big box fan in the doorway and blasted the tents with outside air. For about 4 hours a day. And I swapped to a day off night on with the lights. Even leds you'll drop 3-5°. That could make the difference. It saved me a solid 5-8°f depending on the humidity mostly outside. Even for a short time I think it made a real difference. The plants showed signs of stress but the buds themselves were much less.
    Another thing you could do for veg (I don't think it'd be a good idea for flower) is less light if the heat is high. I have a couple males out in a sunroom that get nearly no direct sunlight. They are growing awesome. We push these plants for max yields in minimal time. Slow it all down if you have an issue you can't fix and it'll take longer but be healthier for the plants. But not in flower. That's timed.
    And one last thing. You can vent outdoors rather than in the room. That'll make a good difference too. Idk if you are or not but if not.
  13. But best option is ac. And it is worth it.
  14. My nitro express plant prefer 80 to 85 degrees no airy buds nice thick buds any cooler than that their growth really slows
  15. as temps rise so do pest probs

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