Humidity

Any advice would be grateful.... what should the ideal humidity in a tent be? I have 8 plants growing and I have just flicked them over to 12/12 but at night the humidity is reaching 90% and the leaves are wet by the morning, when the light is on the humidity is anywhere between 70-80%... if it is too high how can I bring it down??

The easy answer is a dehumidifier but I've never used one so I can't comment on those. I will say that more air movement in the tent for starters is very, very important. Perhaps two oscilating fans and a few smaller fans too on all the time. I have a 3x3 tent and I have one big oscilating fan and two smaller fans running all the time in flower. That's in addition to an intake fan and extraction fan. Also if it's warm in the area use an air conditioner. If it's cold use a portable heater. Technically RH actually goes up with cooler temps, but either an air conditioner or dry heat may help depending on the other variables. I've found combating humidity is more art than science. You have to experiment with what works for your grow area. There are little things you can do as well. For instance, I grow in soil, and after I irrigate in flower I spread a thin layer of dry soil on top of the wet soil. I also make sure to clean up all drips from the pots. You also want to irrigate as soon as you can when the lights come on. I also use 5 gallon buckets which mean I usually only have to irrigate once a week.
I will say that you can't expect miracles, in that if it's raining outside it's going to be humid, that's where the air flow comes in. Even in humid conditions if you have good air flow you can get away with it for a little bit.
I know this doesn't help your current situation but for next time you can also take a big picture approach in that you can avoid late flowering in months that it's really humid where you live. For example, august where I live is a bitch for humidity. I'm going to avoid late flowering in august by timing the grow around the more humid months. I'll veg in august but I've found flowering in august is too much of a pain in the ass.

yes get a dehumidifier it was take that problem away instantly. my question is can too little humidity harm a plant? for instance currently my humidity is at 25% and my leaves are wilting can this kill my plant?

yes lower humidity . is not a good thing . below 30 % you need to spray them with a mister . problem solved. I keep flower 45 . veg 55 . clones 60 to 70.

see i tried to spray with a mister before and it caused powdery mildew also is it ok that i mist i am three weeks from harvest is that ok?

OP, I agree to increase air movement in the tent and/or the intake and exhaust. Or get a dehumidifier. Humidity can fluctuate a lot depending on weather conditions as well. Around here it was running 60% ambient for a while, now it is running 30% due to a high pressure system in the area. Maybe check the forecast to see what weather is likely to move in in the near future.

Freedom35, Don't spray the buds if you are 3 weeks from harvest. If you must mist just hit the leaves, maybe try to add a bucket of water or a wet towel to the grow room as an alternative. 25% RH will not kill your plant though.

After getting bud rot on my first grow from "misting" during flowering I don't even allow a mister on my property.

Thank you everyone for the comments they are much appreciated and have helped me out a lot, so thank you all!

Thanks all .... I have increased the air movement in the tent and left window in room open 24hr and its dropped to 65 which is a lot better and no water droplets in the mornings phew !!

So yet again your knowledge is my saviour as probably will for years to come lol.

Edgar9 said:

After getting bud rot on my first grow from "misting" during flowering I don't even allow a mister on my property.

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You can spray your plants. It needs to be done when the lights come on @15-20 minutes after the girls wake up.
If your spraying in the dark cycle you can run into problems if you don't have good air-flow.

Good Luck on your Grow.

topfuel29 said:

You can spray your plants. It needs to be done when the lights come on @15-20 minutes after the girls wake up.
If your spraying in the dark cycle you can run into problems if you don't have good air-flow.

Good Luck on your Grow.

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You're right you can, but because getting bud rot was such a traumatic experience (I actually shed a tear) I don't even "go there".

this dehumidifier will bring humidity down around 20-30% it just runs off a fan hitting metal to create condisation and it drops down into a container. you can pretty much build yourself one with a computer fan and a box with a cpu heatsink ( copper or aluminum will work ) and a cup below the heatsink. i personally just bought the dehumidifier since i dont have time to build one.

My humitidy levels under my 250 HPS are near 40-45% . I am switching to flowering this Monday.Should i just let it be ?

45 is fine for flower, I agree with kind diesel with the range's he posted. if you are under 25 you will notice your leave's drying-getting crispy