Leave edges curling up

Eric Farley

Eric Farley

Active Member
I noticed tonight that the edges on my leaves are starting to curl upwards. I did a search and the common cause for this is heat stress. However I keep my canopy temperature at 75-78 degrees during the day and around 65 at night. Since my temps are in the butter zone I have trouble believing I'm having an issue with heat stress.

Does anyone have any ideas what might be causing this?

I'm growing under LED lights in a DWC system. My lights are 8-14 inches from the plants but I can't raise them any higher. The plants are in week 10 since switching to 12/12.

Some leaves are worse than this, some are better, this is somewhere in the middle.
 
DirtyMcCurdy

DirtyMcCurdy

Well-Known Member
Whats your humidity? I'm guessing its a little on the low side however, you say they're at 10 weeks so I wouldn't worry that much.
 
Eric Farley

Eric Farley

Active Member
DirtyMcCurdy said:
Whats your humidity? I'm guessing its a little on the low side however, you say they're at 10 weeks so I wouldn't worry that much.
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Yes it's intentionally low, I had heard that lowering the humidity late in flower increases THC production. I'm running 36% RH currently, I'd actually like to get it down to 20% but I haven't been able to get it below 35% as that's the lowest setting on my dehumidifier.
 
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Alienwidow

Alienwidow

Well-Known Member
Temps are good. Id say no heat stress. Upcurl is common when your at the end. Sugar leaves like to curl upwards especially at the end. Its a sign of finnishing. No worries there.
 
Eric Farley

Eric Farley

Active Member
Alienwidow said:
Temps are good. Id say no heat stress. Upcurl is common when your at the end. Sugar leaves like to curl upwards especially at the end. Its a sign of finnishing. No worries there.
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Ah great, yes they have about a week and a half left before I chop them.
 
DirtyMcCurdy

DirtyMcCurdy

Well-Known Member
Eric Farley said:
Yes it's intentionally low, I had heard that lowering the humidity late in flower increases THC production. I'm running 36% RH currently, I'd actually like to get it down to 20% but I haven't been able to get it below 35% as that's the lowest setting on my dehumidifier.
Click to expand...
The main reason to lower humidity late in flower is to help prevent mold growing in the buds. You are fine because you are about to harvest but normally you don't just run the humidity as low as you can get it. Look up "vapor pressure deficit" to see what I am talking about.
I don't know if there is any proof that it increases thc production, maybe there is? Idk. A lot of others do the same.
 
Eric Farley

Eric Farley

Active Member
DirtyMcCurdy said:
The main reason to lower humidity late in flower is to help prevent mold growing in the buds. You are fine because you are about to harvest but normally you don't just run the humidity as low as you can get it. Look up "vapor pressure deficit" to see what I am talking about.
I don't know if there is any proof that it increases thc production, maybe there is? Idk. A lot of others do the same.
Click to expand...
I'll look into that, I run my humidity at 60-70% for veg, 50-60% for flower and I try to drop it down as low as I can go for the final couple weeks. Since I'm still learning this strains timing I started dropping my humidity earlier than I would next time.
 
Moldy

Moldy

Well-Known Member
Eric Farley said:
I noticed tonight that the edges on my leaves are starting to curl upwards. I did a search and the common cause for this is heat stress. However I keep my canopy temperature at 75-78 degrees during the day and around 65 at night. Since my temps are in the butter zone I have trouble believing I'm having an issue with heat stress.

Does anyone have any ideas what might be causing this?

I'm growing under LED lights in a DWC system. My lights are 8-14 inches from the plants but I can't raise them any higher. The plants are in week 10 since switching to 12/12.

Some leaves are worse than this, some are better, this is somewhere in the middle.
Click to expand...
I had the same issue when it was 100F+ outside. It's 20% RH here in the desert but I usually grow indoors. This was an experiment on a skunkberry and my leaves really curled up when it was that hot and very little breeze. I can't say if that's your issue but it I'm pretty sure the heat caused my curling.
 
Eric Farley

Eric Farley

Active Member
Moldy said:
I had the same issue when it was 100F+ outside. It's 20% RH here in the desert but I usually grow indoors. This was an experiment on a skunkberry and my leaves really curled up when it was that hot and very little breeze. I can't say if that's your issue but it I'm pretty sure the heat caused my curling.
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I said my temps are 75-78, if my temps were 100+ I would already know what's causing it. 75 is a long ways from 100...
 
W

wiethe20

Well-Known Member
Eric Farley said:
I'll look into that, I run my humidity at 60-70% for veg, 50-60% for flower and I try to drop it down as low as I can go for the final couple weeks. Since I'm still learning this strains timing I started dropping my humidity earlier than I would next time.
Click to expand...
Ok sooo I believe what you believe as wel, and I'll explain to you how I got told...when keeping RH as low as possible to create more gland heads...as you are in the "butter" temperature and a low rh makes the plant think it's way more dry then it actually is, and mj pushes these glands heads of to "protect" it's water...so I lower mine as much as possible too! I'm sure people will go ape shit and say I'm wrong butttttt to each his own...just what was passed down to me
 
Moldy

Moldy

Well-Known Member
Eric Farley said:
I said my temps are 75-78, if my temps were 100+ I would already know what's causing it. 75 is a long ways from 100...
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Sorry I wasted my fucking time. I said it was 100F that caused MY issue just for a reference point. I didn't say that heat was your issue.
 
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