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May 11, 2011
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I need to know what the effects are of a dehumidifier and when do I start using it. I hear that the last 2 weeks of budding is the time. I have a dh but dont know how and when and why.
I have not read anywhere about the last 2 weeks being a particular time for dehumidification. I assume it is something to do with powedery mildue or budrot or ane of the other humid nightmares that can occur. If so, I would think you need to keep your rh below 40% but I could be wrong.
In my experience, the plants are happiest when 40% to 60% humidity is maintained throuout the life of the plant. However, the seedlings and clones do better at about 75% for the first 7-10 days, and a lot of people like to reduce the humidity to 40-45% max during flower to avoid the nasties that accompany high humidity. I discovered that when the room gets above 75%rh, the plants will actually slow down their growth as they aren't able to "sweat" transpire in the warmth. Also the higher yer heat in yer grow room the more they will drink and "sweat" causing the humidiy to quickly jump up. I run my DH all the time but it has a setting that maintains the percentage that I want. right now I am really recycling a lot of water from my DH as all are in flower and its quite warm here. If yu don't have one, get a good digital hygrometer (not expensive) so that you can maintain yer RH for better results. good grow mojo
I use a DH during flowering as well- it has the doubly nice effect of lowering the humidity and raising the temp just a bit in my small, cold, humid growspace. My book suggests that higher humidity is best for veg and especially young clones with lower H good for flowering. I don't have the book in front of me to quote you the exact numbers, sorry!
agree with hushpuppy. in early flower i wouldnt let your room get any higher than 60%.
i always turn the DH on 2 weeks into flower

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