What Humidity % for during flower???

plantz

Well-Known Member
My tent is at about 80 degrees with 35-45% humidity. im 2 weeks into flower and im wondering what my humidity levels should be.
 

Heads Up

Well-Known Member
Here in florida it is very common for humidity to be above ninety percent in the mornings. It's ten minutes to eight in the morning right now, the temp is sixty three and the humidity is ninety percent. Personally I think people make to much of an issue about humidity. I use a dehumidifier in my grow room. I'm into my second week of flowering and my temp is seventy six and my humidity is fifty four percent. Humidity really only becomes a problem during flowering if you have really high humidity and really thick buds, say above seventy five percent. Than you have the potential for bud mold. Air movement also plays a part. I also run an air conditioner and two fans in my room. With higher humidity levels your plants will need less water. With low levels your plants will need more water. Also during flowering with low levels of humidity such as yours, your plants will throw out more thc crystals to try to protect itself from drying out. I think that is why people shoot for lower levels when flowering. I have two buddies who also grow. One grows outside and one inside. The bud grown outside is way better than what we have managed to grow inside and those plants lived through many a night of super high humidity.
 

robert 14617

Well-Known Member
What range should I maintain for my growroom humidity and temperature?

What range should I maintain for my growroom humidity and temperature?


A humidity and temperature gauge are essential in any growroom. Daytime conditions should be 70-80 degrees without co2, 80-90 degrees with co2 until the last two weeks when daytime temps should be kept between 70-80 and co2 can be reduced to adjust for the lower metabolism. Night temperatures should be kept above 60 degrees to prevent stress. It is preferrable during flowering to have a night temperature drop of 10-20 degrees to stimulate flowering hormones and reduce stem elongation.

I find that low humidity causes stress on plants. I recommend 50-60% humidity until the final 2 weeks of flowering. At this point, the humidity should be lowered as much as possible to encourage the plant to seal and protect itself with additional resin. (I am able to get the humidity to go as low as 31%) I have been able to frost things up considerably this way. The higher humidity levels prior to final ripening reduce salt levels within the plant tissue and encourage healthy, more lush growth.
Added on: Tuesday, May 1, 2007 Viewed: 14894 times
 

pixils

Member
I noticed when I use co2 the temp inside the tent goes up 5 degrees, but the humidty goes from 40 pct up to 70, I am still vegging, butI hope 2more weeks and I can go from 24 hours down to 12 and12, and I will put the humidifier inside the tent and drop it lower.
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Ou8aCracker2

Well-Known Member
For veg and up to the end of intial stretch in flowering...50% to 65% (read up on vapor pressure deficit).

For the rest of flowering,no more than 50%.

The last 2 weeks you can try dropping it to about 30% to see if it makes your buds pack on a few more trichomes.
 

mrgreen2015

Well-Known Member
For veg and up to the end of intial stretch in flowering...50% to 65% (read up on vapor pressure deficit).
For the rest of flowering,no more than 50%.
The last 2 weeks you can try dropping it to about 30% to see if it makes your buds pack on a few more trichomes.
I agree. Did a lot of research when entering the flowering stage. On week 6 now. Was battling humidity. Hopefully you have an AC in the room. Leave the AC & dehumidifier on. Set whatever temp best suites your plants. Humidity should be at 50% or below until final 2 weeks. Then drop it low as possible to produce more resin. :)
 

KidKnicky

New Member
Keep in mind that there is no set rule for every grow, these values are merely guidelines for the grower to work with.
Your environment, how it behaves, what is interacting with, will have a lot to do with how things are set.
Also, your equipment is important as well. All that hardware adds to heat...
Different strains will also behave differently under set rules, you have to be flexible or "dynamic" as needed...
I'm working a 1200 plant GG with 10 rooms. Some of our biggest challenges are with equipment. As we add dehu's, heat is an issue and the a/c's can't keep up, things like that. Also, PM. Keeping things cool and dry enough at night to limit outbreaks...

But on topic, we run veg @65-75 rh
week 1 flowr @ 60ish
Week 2/3 is where we begin to work this down, 55ish
You can run this through week 5/6 around 45-55. your plants(strain) will show you what they prefer...Watch Them Closely.
With our feed program, we are getting massive bud swell late in week 6 into week 7. Dropping RH at this time and adjusting temps down in the last week is huge. The problem here is the DP(Dew Point). We do not have heaters in our rooms and temps are still dropping (outside) to -8C.
As the temps drop, so does the DP and the Dehu's are icing up trying to keep up. We are forced to increase day temps and RH just so we can get through the night before lights on. For instance, I have to keep my night temps above 70 and rh above 40, just to stay a step above DP so the equipment keeps running and reduce mold risk.
Sometimes, it's not so much what you want to do, but what can you do...
 

Mmcary82

Well-Known Member
My tent is at about 80 degrees with 35-45% humidity. im 2 weeks into flower and im wondering what my humidity levels should be.
I start off at 55% after the stretch is over I lower it 5% a week and hold it at 35% humidity the last few weeks before the slaughter.
 

Mmcary82

Well-Known Member
I start off at 55% after the stretch is over I lower it 5% a week and hold it at 35% humidity the last few weeks before the slaughter.
Really any lower then 35% has no added benefits and only potentially negative benefits as it stresses the plants too much. The main reason I like to have the humidity low is to mitigate bud rot and mold/mildew, there is a strong correlation with resin production better with 35-45% humidity vs higher humidity levels..In veg I like to keep no higher then 70%..But I grow multi strains and have a happy medium. When you work with particular cultivar intimately you begin to find the sweet spots in the parameters to keep her thriving. But as a general guideline high humidity from clone/seedling 70% veg and then start ramping down the humidity by 5 degrees or so every week.
 
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