Leaves curling upwards??? Heat Stress??

The first pic is my garden which seems to be growing fine..36 days into flower..My problem is that on the taller plants closer to the light, Im getting what looks like nute burn/hot spot? I'm also thinking heat stress. Only about a month or so left until I chop em, Im worried though. temp stays betwen 68 and 82 depending on time of day, mostly between 60-70. RH stays between 35-50. Lights are only about 15 inches away from the tallest branches though. 2 Hortilux 600wBLUE. no HPS. ppm between 900 and 100...ph between 5.8 and 6.1 Any Ideas?

I've had that with a few plants so it might just be heat stress and to be honest you should be done in a few weeks so no worries.

Should be 18" minimum.

Why are you using metal halide for flowering?.

Tips curling upward is more often heat stress while tips down more often over-feeding. I'd do some LST and pinching next grow if you can't raise lights anymore.

Bugeye said:

Tips curling upward is more often heat stress while tips down more often over-feeding. I'd do some LST and pinching next grow if you can't raise lights anymore.

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Yeah for sure. I did some low stress training on all of them with soft tie during veg, but not enough, Im using the scrog method next time. Pretty sure they're not gonna get any taller. Would slightly tying them over be bad for them? Or should I just grow them out? the buds look fine, but I'm worried about bleaching.

Oh and Google Hortilux BLUE MH(the spectrum is way different then regular MH) for the poster asking about MH for flowering. Really good lights. I have more tricombs, I vegged MUCH faster, and I can't see any downside so far. Flowering is coming along as it usually does. My heat issue would be worse also if I was running HPS. 1st time using them and I believe what they say about the BLUEs' spectrum is absolutely true. Better overall. HPS certainly does the trick though Oh,btw, here is a pic of a White Fire nug 34 days into flower under these lights.

Here's my garden(day 37 of 12/12) under the BLUE MH. Anyway, I posted this to give you an idea of how close they are to the lights and to see if there are any suggestions for improvement in my grow.

You could tie them down a little if you think heat is an issue. They look good!

Bugeye said:

You could tie them down a little if you think heat is an issue. They look good!

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Thanks the compliment. Lots of time and effort.