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Leaves curling inwards. Light stress?


New Member
Hello all,

I'm running a small hydro set up in a grow tent. I am using LED lights, and General hydroponics nutrients (the Flora series). I monitor the Ph and don't let it get above 5.8. The nutrient solution is fairly week (less than half strength) and the TDS reading hasn't gotten higher than 700.

The root system is growing like mad. However, the leaves are doing something interesting. They are curling in on themselves. I think I've narrowed the problem down to: Humidity (maybe I need higher humidity?), Ph (though, I don't let it get higher than 5.8, it averages at 5.5), or light stress (I've moved my lights higher already), or a magnesium deficiency.

here is a picture of one of the leaves:


Any advice?
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New Member
Yeah, my temps don't go above 80, and the fan isn't pointing at them but off to an oblique angle. Temps hit about 80 on a regular basis, but I try and keep it cooler.


New Member
For sure it is not light burn, with that will get the eagle claw leaves showing up and it will bleach the leaves and bud.


New Member
Hey all,

I'm taking the temp readings at the top of the tent. I'll move the probe down to the foliage tonight. I'm certain that once it isn't near the light it will be a lower temp. The LEDs are very cool (I can touch them), so I wasn't really convinced it was heat stress.

When I first started the grow, I had the LED on 24 hours a day and noticed some bleaching as well as the curling. I thought that was light stress and dropped the lighting to a 20 on/4 off. The bleaching went away, but the curling didn't.

I'll get some epsom salts tonight, do a full nute change (it's due for one) and keep you updated.

Thanks for the help.


New Member
i had this problem several times and i finally figured out (in my case), it was do to a fan blowing dry warm air over the top 1/3 of the plant. does you have any leaf curl below the half way point? i would up the humidity level to at least 60% and maybe move your light up and check room ventilation. good luck
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