Humidity levels, How low is too low?

I have seen posts on here that said anything over 55% will show negative results. Wat if the humidity is around 20 - 30% during flower stages? Is there such a thing as too low?

From what i was told since i too have a low humidity during flowering is that its not a problem. The High humidty is bad because it can increase the chance of mold and other bad things. i was told that lower humidity might make you have to water plants more often and some other things but its nothing to worry about i dont think.

i have heard that lower humidity during flowering is good and promotes plants to produce more resin to protect plant from drying out

hansolo33 said:

Wat if the humidity is around 20 - 30% during flower stages?

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that's right were you want it, too low haven't heard of that ever being a problem but it's cheap to raise compared to lowering it with a dehumidifier.

I have a dehumidifier in my grow room and I set it to 35% when flowering and my plants seem to love it.

I actually have to empty my resevoir everyday and it holds 2 gallons! I have also heard that the low humidity will promote more resin in the buds. I think you will be fine

I agree. The lower the humidity, the more water loss the plants experience. A tricome is far more efficient at water retention than open leaf. The plant responds to dryness by producing more trichomes (and more resin) to "seal" up the plant. It is clear to allow light thru while keeping moisture in. Pretty smart of the plant, but even smarter is the gorwer who uses this to their advantage!

In veg, 60-70% is desired as it aids in stomata opening (the skin of plant material, the more open, the more photsynthesis). In flower, lower as much as you can. I do not believe you can get too low. 35% is the lowest setting on a lot of units, and this is below the min recommended of 40-45%.

It makes a huge difference.

Think about it this way. Humidity is like the economy. When living costs more money, we tend to try to conserve as much money as we can. Likewise the plant conserves as much water as it can. The drier you get it, the better the result.

Take a look at this girl 3 1/2 weeks in 12/12, veg was 70% RH, 35% RH in flower. You will rarely see furry-ness of this nature so early or so intense without low RH. Worthy to note, even the larger leaves surrounding these flowers are loaded up with tris.

passerbye said:

I agree. The lower the humidity, the more water loss the plants experience. A tricome is far more efficient at water retention than open leaf. The plant responds to dryness by producing more trichomes (and more resin) to "seal" up the plant. It is clear to allow light thru while keeping moisture in. Pretty smart of the plant, but even smarter is the gorwer who uses this to their advantage!

In veg, 60-70% is desired as it aids in stomata opening (the skin of plant material, the more open, the more photsynthesis). In flower, lower as much as you can. I do not believe you can get too low. 35% is the lowest setting on a lot of units, and this is below the min recommended of 40-45%.

It makes a huge difference.

Think about it this way. Humidity is like the economy. When living costs more money, we tend to try to conserve as much money as we can. Likewise the plant conserves as much water as it can. The drier you get it, the better the result.

Take a look at this girl 3 1/2 weeks in 12/12, veg was 70% RH, 35% RH in flower. You will rarely see furry-ness of this nature so early or so intense without low RH. Worthy to note, even the larger leaves surrounding these flowers are loaded up with tris.

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looks tasty.
What's the strain if you don't mind me asking?

i always thought 50-60% humidity during flower was ok until the final 2 weeks when you want to get it down as low as possible?

are you guys keeping humidity to about 35% for the whole flowering period?

when the plant doesn't have many roots I like to keep the humidity as high as possible- around 90%. Of course it still needs some air flow so 100% isn't really practical.
That way the plant can feed off the leaves.

Then when the plant have some root system I lower the humidity to around 50-60% in veg as the plant still wouldn't mind some feeding from the leaves.

In flowering they should already have enough roots to take enough nutrients from the soil alone. Buds don't like humidity - it promotes loads of problems.
But humidity of 5-10% isn't that good either - the plants will be weaker as they can barely absorb anything from the leaves, the medium will dry out really quick and so on.

If you live in somewhere that you can get 5-10% in your grow room I advise you to get it up to at least 20%. Thats pretty easy to do - just lower the venting a bit or add a bucket of water to your grow room.

I havnt measured it but having Gas heat will drop the humidity big time. Shit my nose is bleeding every morning due to the boogers being air dried to the insides of my nasal passages. I routinely wake and put water up my nose like I had to back working concrete and then blow the warm water out and see the globs of blood. I was wondering myself if this was helping my girls in flower

My RH levels have been running 60 to 70% (and spiking up around 80% after watering). I'm just one week into flowering and in an effort to bring that down with out running my vent fan a lot (because I'm adding CO2 to the space) I went and bought an EVA-DRY 1100 mini dehumidifier at Ace Hardware for $50. Since the space is only 7x7x8 I figured that would be big enough and that a full sized dehumidifier would be over kill.

I've had it for a week now and while it's pulling some water out of the air in the space it hasn't made any real difference in the RH levels. Maybe it would be sufficent for a cabinet sized grow space but it's definetly not enough dehumidifier for a 7x7x8 closet grow space. So it looks like I'll be shopping for a full sized dehumidifier this coming week.

Does any one here have any recommendations as to make and model of a dehumidifier they've been using and liking?

Im the same - after reading this thread you realise how important they are... i was using something similar to the eva dry called a moisture trap and whilst it removes moisture it doesnt remove nearly enough to get that hygrometer reading down enough... I definitely want one with a humidistat but i have very limited room so i guess ill need to go with whatever fits my grow cupboard lol

Ive also noticed that they may say that they drain 10L per day but the tanks can only hold say 1.5L before they need changing

can anyone give us some advice on what we should be looking for when purchasing a new dehumidifier?....

what size tank do you think i would need for a small cupboard grow with 5 plants?

This is a 4 way mutt strain. Mom was a Skunk#1/SilverHaze Dad was Granddaddy purple/pineapple express. GDE hit our area as a designer strain last year. pretty good stuff. He crossed it with an old school girl he has grown for a while.

The offspring were interesting. This ones in the pic were more sativish....others were squat and more kushlike. The best girl grew strong and tall and looked like a 1976 Skunk#1 throwback. bottom cola as fat as your fist. See one of the latest picvs in the middle is that cola. It weighed more than 1oz cured.

I spared no expense and these girls got the maximum love possible. LED and UVB lights mixed with HPS produced crystals like I have never seen before. It's not god's vagina, but the trich count was off the scale. Pure water last 2 1/2 weeks. Got them bone dry and wilty 3 times during grow. RH was 20-35%. Once the girls had coated themselves, the dehumid had a much harder time pulling moisture from the air. For some reason, at the end I let the temp go to 105 20% RH. It happened by accident. lights on at 7. fell asleep and at 10am it was 105. I opened the door expecting all wilting and not one girl was affected. We let the temp build the last week and they took 104-105. Leaves finally turned yellow exhausted at 9 1/2 weeks. These girls were stubborn! But worth the wait. Each day it built a layer of new flowers. amazing.

so trust me. GET A DEHUMIDIFIER! it also helps during drying. I bought 70 pint from Sears for $350 planning to return it. It justified its cost the first time used.

These pics were at 6 1/2 weeks. they put on some serious weight in the home stretch.

Mine is a 70 pint unit. but the most it ever pulled out on one day was 5 gallons. thats only 20 pints. But I think the pint rating is more an indication of its power. they also produce heat. I have a big space so i got a big one. its 3 feet tall and rolls. better too big than too small. mine never got below 20 in the room even on continuous.

If you are watering your plants enough, I would go to 20 if you can in flower from day1.

Here is one for $175. For a closet, I dunno. u would want to prolly duct it as the units tend to be big. In a small area, you have limited choices sometimes.

http://www.rainbowappliance.com/FDFxx1.html?utm_medium=shoppingengine&utm_source=googlebase&cvsfa=673&cvsfe=2&cvsfhu=464446787831

you can also hook a hose up and have it drain automatically. I collect my water and reuse it. Mine 70 pint kenmore also have a built in pump. neat feature.

i saw a mini one for £50 which extracts 350ml per day but im guessing thats nowhere near enough...

space is a major issue for me - im gonna have to rethink all of this once i get some cash together

more than likely ill need to buy a few large grow tents and then i can sit a dehumidifier on the floor where it belongs, it would just be too big and bulky and too heavy for me to mount it in my cupboard just now (its only 0.5m x 0.8m x 1.7m) - i know i need one, but maybe im best to wait til i get myself a bigger growing area?

so if i was to get one, how many litres a day do you think it would pull out my growroom?

I only have 5 plants at the moment