Say a plant is 6 weeks into flowering and used to 50 RH. What happens when it drops to 30 RH overnight?
I’m trying to figure out why both of my plants have went limp.
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Depending on your setup, could be a few things. But the simple answer is not enough water in the air.
The humidity level will change if the grow space climate changed. Heaters will dry the air. Colder winter temps = less moisture. You may need a humidifier to bring it higher.
If you are using fabric pots or regular plastic (or terra cotta?) The soil may need a good soaking.
Wilting could be due to under watering. Is the soil dry and hard to push into?
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Could be a few things. Usually it’s over or underwater. Your RH will play a big role in that if it’s too humid the plant will retain moisture and same on the inverse. I live in a humid climate until a cold front blows through. Using a tent creates a sealed (somewhat) micro climate that is more manageable. It’s a matter of watching your numbers and having equipment to manage the variables.
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These are in a 4x4 room(closet). One is DWC and one is coco/perlite/soil mixed with a wicking pot in a fabric pot.
I use a cover over the doorway and adjust the gap at the bottom for air to enter the room from my conditioned living space. (2) 4” ac infinity exhaust fans. I keep it in a negative pressure.
I have a humidifier and dehumidifier, watch the VPD and overall temps.
When this problem occurs is when a cold front comes in and during lights off. The humidifier goes off at night because the humidity rises during lights off. I’m keeping that range in between 35-55 percent( typically 45-55). They are deep into flowering so I’m keeping it 55 and below to help prevent mold issues.
It stays between 68F and 78F roughly, it’s that humidity swing that gets me and the only thing I can think of.
Imagine your plant normal, reaching for the light and is in the bud fattening stage, the final few weeks.
Overnight when this cold front moves in the humidity drops to around 35 and the next morning all of those heavy buds are laying over and the stems feel weak, not stiff like wood anymore. Flexible, to a degree.
This happened with both plants. One plant, the soil one, has a branch that goes from near the base to the top with a large cola on top. This one fell over and literally split from the main stalk.
I know a net or yoyo would definitely help or fix the situation, it’s just odd to happen overnight. I haven’t experienced this before and trying to figure out if it’s the humidity swing or something else.
So when I found the room at 35 RH and the plants wilting like that I turned the humidifying on max to get it back into range, which may have been too much too fast.
I know seedlings and clones need dampened off and think maybe something like that happened here.
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I’m fighting similar issues with the weather swings. I was having sagging and at one point I was getting droplets one the leaf edges. I got on here and was suggested to get a dehumidifier. That seemed to rectify everything. Stay pretty dry and just allow lung room intake to increase humidity.
Might reduce the humidifier usage and let them dry out pretty well then try to slowly introduce humidity?
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Does the humidifier put out hot, wet air?
Or are you using a cool mist humidifier?
If it’s the hot air version, you may be steam-cooking the plants. If it goes out at night but you’re intake is pulling the dry air from the outside room space, A possible solution would be to ensure the entire room, not just the grow space has more moisture and then have a cool mist (sometimes a reptile humidifier, but many types out there) for inside the space. So put the hot humidifier into the open space, near the tent with a smaller, cool mist in the grow space. Most Pharmacies, Walmart, etc. have small ones that last up to 6 hours. AC infinity has a few that can do 1 to 3 gallons, but are more costly.
If the limbs are too thin, they may just not be strong enough, they can droop with the weight of the bud, which will only get worse. If that is already happening, I’d suggest getting a net or string one together.
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Thanks. It’s one of those cool mist humidifiers. While the lung room has a low RH at night, the room itself was staying a minimum of 45 at night. I have the fans lower when the RH Drops so it keeps air moving, but enough to moderate it.
So you think the RH swing is doing it then? I have the humidifier humidify the room where the 4x4 get’s it’s air from and turns off at 55. It’s a 2,000 Sq ft humidifier in a 140 square foot area. I typically just run it on a lower setting.
Yea it’s like the whole plant went from stiff to flexible. The limbs with more weight and longer stems are the worst. I’ve tied her up the best I can, but all they want to do is lay down even after adjusting the RH and keeping it right the last couple days.
That’s the only thing that changed though, so you agree it’s probably the RH? I think It’s fine they are close to harvest but next time around I would like to avoid this.
I’m trying to get one of my plants to go 50/50 amber to see what that feels like but it seems something usually happens that won’t let me harvest it late, haha.
If it’s the RH though, it seems changing that they would perk back up in a few days right? They are less “flexible” now and it has kind of “locked” in the droop in the stems so I can’t put them back where they should go without breaking them. I’m not sure if that is to be expected or not.
it could also be the soil in the pots. with air that dry, my guess is the soil is not able to stay moist and the dry air is pulling too much too fast, especially if you’re using fabric pots. when you water them, does the water sit on top for a while before draining down into the dirt? that’s an easy sign of soil that’s way too dry. I sometimes have to put some water on top, wait until it passes through, then give smaller “sips” until I see the water drain into the saucer under it. Then I know she’s had a decent drink.
I would make sure the soil is naturally damp without being too oversaturated. that would likely raise the overall humidity in the space as well. As more of that water in the soil seeps away from the dry air and the plant’s needs, you may need to start watering more, or just more frequently. This could really help keep the plant healthy while not letting the soil get muddy.
Are the leaves going crispy? Not just the ones being cannibalized as flower demands more nutrients, but is the whole plant looking like it’s thirsty? do the leaves curl up on the edges? Or is the biggest issue the drooping?
Technically, the Humidifier goes “silent, passive, or enters the off stage”.
The humidifier should activate or turn on, during the Lights ON cycle or dry atmospheric conditions…
I use one tent humidity increases during lights off to provide humidity and heated air to the second tent (connected). Clearly changes the numbers Temp and RH.
Sudden temp change (-20F) froze off all leaves in 20 seconds one night, while moving the plant between heated buildings (never did that again).
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