humidity ????

Discussion in 'Growing Marijuana Indoors' started by joshterese, May 26, 2010.

  1. HI-
    I am on my first grow. Using an Aeroflo system. We live in Colorado were there is about 30-35% humidity. We have started our seedlings they are about 2 weeks old. I think we need more humidity. Have tried a regular household humidifier which doesn't seem to do much. A tray of water doesn't help. Our hi-lo sensor shows room humidity between 30-50%. It seems like it is usually around 35-40%. We only run the exhaust fan for about 15 minutes per hour so that a little bit of humidity remains.
    So my question is how do I increase the humidity. I think I would like to run the fan more often. My room is 7x12x8. Temp 70-82.
    Also where should I have my air thermometer? Should it be right with the plants under the lights? Or just off to the side.
  2. #2 I have this, May 26, 2010
    Last edited by a moderator: May 26, 2010
    I keep my thermometer equal to the closest portion of a plant to the light, so basically, the hottest spot.

    As far humidity, I think you will hear a lot of different opinions on ideal numbers. I have heard people say that low is good. Others will tell you you need to get it up to 50-60. Where I live it's not an issue so I dont know what some good solutions people have come up with are, intuitively I would think a humidifier..

  3. 2 weeks old.. 60% is what i do. works great. no lower
  4. You need to run the exhaust fan at all times. Plants should receive new air constantly. I live in the desert and the humidity is usually 0% except before sun rise when it climbs up to 10% sometimes 15%. None of my plants have issues.

    Letting a grow space gain humidity by stagnating respired air from plants is inviting mold even at low humidity because the plants become sources of food and moisture. To avoid this constantly exhauast respired air. 35% humidity is perfect for flowering plants.
  5. But hes not flowering yet so 35% humidity is not what you want i dont care what ppl say.for veg you want 60-80% for flower anything below 55% is usually good.seedlings need 80-100% humidity.thats why i use a propagation green house with a tall dome for the first 2 weeks when seedlings are fragile..the high humidity helps them in the most fragile part of the whole life of the plant.after 2 weeks or the seedling stage is over i take out of dome and into 1 gal pots with humidity not below 60%

    thats why i have 2 different sections..a veg room with a humidifier and a flower room with dehumidifier.your not gonna get mold a veg plant.idc if the humidity is high as balls..mold is caused by not enough air circulation and high humidity around the bud sights.seedlings are prone to infection and disease so high humidity helps them fight it off.
  6. 35-40% is alright. High humidity creates a habitat for insects and mold iwhen in flowering. High humidity(80%)is best for seedlings seedling.
    I live in desert climate and around 16%h and my GR is 20-30%. I been taking plants outdoors in higher heat and lower humidity and the plants are just loving it. Has a lot to do with what part of the country your stain originated as to humidity and temp.
  7. Afganistan is a desert. The Hindu Kush is an arid mountain range. Yes plants in veg do well in 60% humidity as do plants in jungles with high humidity, but air circulation is more important. The only way to raise humidity is to decrease air flow in an arid climate. Most plants do fine in low humidity during veg. You just have to water more often. Do not sacrifice air circulation to raise humidity to an optimum level the benefits do not out weigh the negatives which are mold and insects.
  8. I wouldn't worry about it.
    Optimum R/H for veg is 60-70%, light on or off
    flowering 30-50%, there alot more resistant to mold & disease
    during vegging than flowering, the only time I've had a mold issue was
    high R/H & a temp swing causing condensation during veg, also a 14* temp
    swing in 24 hours can trigger a mold outbreak.
    If you feel the need to increase it I would suggest getting a humidifier,
    2nd hand stores are great for them, clean it well with bleach & water.
  9. grow them in a non ventalated room like a bathroom i did and grew amazing never below 50% humidity and also water them and have less air circulation. this creates more humidity mist them not water the soil.
  10. Thanks for all the advice. I just turned the fan on constantly and ordered an evaporative humidifier. I already have one humidifier but I guess one just isn't enough. Maybe the evaporative is the key. P5260298.jpg

    P5260302.jpg Here they are -2 week old seedlings

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