Humidity

Discussion in 'First Time Marijuana Growers' started by realdozzy, Jan 30, 2013.

  1. I have just put the thermometer in my grow room for a dry run before i put the plants in there the temperature is 18oc and the humidity is 71% i know how to get the temperature up but could someone please tell me how to get the humidity down please.
     
  2. the humidity is fine for veg, you just need it to be lower in flowering to avoid mold. theres ventilation and theres electric dehumidifiers, though I havent used one yet and have no idea how they work.
     
  3. i have now got the humidity down to 66% it does not seem to want to go any lower will this be ok for growing autos.
     
  4. autos in general are no different from photos in this regard, just like any other except for the flowering trigger mechanism.
    Im no expert on this, but I believe for veg 60-80% humidity is good and for flower 40-60. so for an auto its gonna be completely fine like this for at least a month. personally I wouldnt worry about anything other than >70% in later stages of flowering.
    you can expect humidity to be higher with plants of considerable size vs no plants. the leaves transpirate much more water than the soil if pot and plant size are adequately matched.
     
  5. That humidity is fine. FOAF has kept flowering plants in a cold closet overnight during the winter (prime time for mold) with humidity reaching up to 90% without any mold. Just make sure they get well ventilated during the day and you'll be fine.
     
  6. i keep mine at 50% with a dehumidifier. without this it would keep rising until it suffocated the plants. higher heat will lower humidity. i wouldn't worry too much until it got to 70% or stayed over 60% for long periods of time. can you raise the ventilation? that should lower the humidity, on condition that the air coming in is lower
     
  7. I have no way of raising the ventilation as the room is totally air tight except for my extractor fan. I am going to try a home made dehumidifier that i have come up with. Its just 2 empty paint cans the first has a quarter inch hole drilled in the base and that just sits on the top of the other can. In the lid of the first can i have fitted a computer fan and filled the top can with rock salt. The computer fan should suck air into the salt and then any water in the air will be attracted by the salt after a couple of hours the water should then start to drip into the lower can so that i can just empty it as and when needed.
     
  8. Rice will work as a dehumidifier...just toss it out when it gets soft.Kinda ghetto I know.
     
  9. that isn't going to effect the air at all really. it won't drip water, if its fully saturated it won't take on more water. I take out 3 litres a day with my dehumidifier, every day. what about getting a bigger fan?
     
  10. sorry when i said rock salt i mean the type that they put on the roads it is slightly different to the rock salt that is used for cooking.
     
  11. proper ventilation of the grow space is the easiest way to lower humidity. i keep it at 30 percent for veg and flower. between 30-50 percent humidity is optimal for cannabis.
     
  12. salt will take on water but to become fully saturated it will take ages, and once saturated you will have to throw it out and replace with dry. but even then the amount of water it will take out will be pretty minimal.

    how about buying one of those boxes that you can attach a tumble dryer to. a condenser. I don't know how efficient they are or how they work but they only cost a tenner and you hook up a fan to it, blowing through the box
     
  13. I think that i am going to have to go down the fresh air route. I didn't really want to put a vent in with an extractor fan fitted sucking air in as when the plants get into the flowering stage the smell will go out through the vent., And as the grow room is in a seed storage shed on a farm that does not belong to us we need to keep the smell out of the shed. (we rent the seed storage shed for doing cars up in.)
     
  14. can't you just use a carbon filter?
     
  15. i have now got my humidity down to 53% and the temp is 23 degrees c. seedlings going in there pots 2moz. Then just a waiting game.
     
  16. that is actually too low.
     

  17. what is? the humidity or temperature? 53% and 23'c sounds spot on to me
     
  18. the humidity is slightly lower than optimal, so he shouldnt try to get it down any more. temperature is good.
     
  19. i find 50% is perfect, but im fully happy with anything between 40-60%. if it goes above 60% plant's respiration will start to slow so i would sort that out. it would never go below 40% where i am so thats never a concern
     
  20. ya you might be right xD
     
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