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What's worse? High temp or high humidity?

Discussion in 'Growing Marijuana Indoors' started by Bubbleheadslbc, Apr 6, 2010.

  1. #1 Bubbleheadslbc, Apr 6, 2010
    We're 5 days into our first grow. We have a 31" x 31" x 71" grow tent, 6 plants in a bubbleponics setup, 250HPS, 2 x 42CFL and 125CFL. The temps and humidity fluctuate a lot.

    Daytime with lights on and 4" exhaust fan running at full, the temp inside the tent ranges from 80 to 87 degrees with the humidity ranging from 30 to 35%. The ambient temp in the room where the tent is located was 77 degrees.

    Evening with lights on and 4" exhaust fan running at 60%, the temp ranges from 70 to 75 degrees (perfect) with the humidity at 40% to 45% (50% to 60% would be ideal?)

    We have been hanging damp towels and it seems to help. We also placed a cup of wet paper towels on the floor by the air intake vents.

    Is there anything else we can do? What's worse, high temps or low humidity?
     
  2. #2 thelizardking, Apr 6, 2010
    High temps are an issue, but low humidity can cause explosive growth if you keep them well watered. The most healthy plants ive seen were in a 15% humidity room...
     
  3. #3 Bubbleheadslbc, Apr 6, 2010
    we thought so. we're going to try placing a big bowl with ice in front of the fan to try and control the heat in the daytime. thinking about changing the light cycle for flowering to have the lights run at night and the dark period during the day. hopefully this will help too.
     
  4. #4 TearDownGod, Apr 6, 2010
    Can you at all elaborate on the grow box issue? there could be better ways of dealing with this seedling then a fan and ice ;) haha.
     
  5. #5 newbhydrogrower, Apr 6, 2010
    At the very start of my grow (from clones) till about 20 days into veg my RH was always low, as more of the plants grew my RH increased from 40 to 70 and my temp got close to 90 degrees. I am in flower now but my humidity is high, sticking around 75%.. I need to get a de-humidifier since in flower I heard high humidity is not so good for the buds. With high heat though, you will heat stress the plants if you do not have fans blowing inside with lots of ventilation. I know since it happened to me :(. To me heat is the greater foe. Good luck.
     
  6. #6 OD420, Apr 6, 2010
    yea humitity that high your just asking for mold and mildue
     
  7. #7 colestoned, Apr 6, 2010
    high temps are definitely much worse than humidity..if you keep under 80 you shouldnt have a problem with powdery mildew at all. low humidity is fine..your plants will get the water they need when you actually water them so how dry the air is really doesnt matter too much compared to the temp
     
  8. #8 Bubbleheadslbc, Apr 6, 2010
    So far today, the temp in the tent was at 84 degrees and humidity was down to 30%. We keep the grow tent inside of a PVC shed (7' x 6') outside the house. I currently have the exhaust venting out a dryer vent on the side of the shed. I cut out a couple of vent on the shed to try and lower the temp inside. I think this the why we are having such high temps in the tent. I assume I'm that same problem an attic grower would encounter.

    Would it be better to have the air intakes on the tent pull air from outside the shed?
     
  9. #9 colestoned, Apr 6, 2010
    outside air will have alot more co2 which your plants need..but you also need to make sure your intake air is clean and filtered or you'll end up having a shitload more problems than just your temp being too high
     
  10. #10 joe_fresh, Apr 7, 2010

    i agree, high humidity can cause pm, mold, bud rot, ect....

    high heat can cause the plant to drink more water than ferts, so you wanna water down the fert solution a bit, heat stress, but this can be avoided by moving your light up, and by high heat i mean more that 35C, i keep my room at 28C but it fluctuates up to 32C, if i want i can get it down to 20C but i got pm from having the temps too low and the rh too high
     
  11. #11 5thgear, Jun 1, 2010
    how have your grows been at these temps?
    my room stays at the same temperature, but I read from some here that its too hot.
     
  12. #12 skiweeds, Jun 2, 2010
    high temps are worse for sure. stronger ventilation can help with both high temp and high humidity. you shouldnt have a mold problem if you keep ventilation strong.
     

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