Leaves curling up on my auto-flowers.

Hi guys, first time posting here and first time grower.

I have a few Northern Lights Autoflower and a few photo periods, Skunk#1 and few unknown strains. All my autoflowering plant leaves are starting to curl up quite badly with some curl on the photo period plants. The photo period plants are a week older and were under a crappy light for the first four days of their lives.

Setup:
600w Dual spectrum HPS.
75% 3 week fertilized soil 25% perlite. No added nutes currently.
18/6 light cycle.
Watered every 2-3 days.
Temps are a tad high at times 80-85f.
Humidity is killing me. Struggle to get higher than 40% when lights on (thinking this could be the issue).

Here's a few of the NL...



As you can see starting to curl up pretty bad.

Here's a PP plant in the same pots..



Some curl but not too bad.

Here's the whole setup..




My thoughts....

Heat: It looks to me that the pots that are less filled with soil are creating some sort of heat trap as ones that are more filled show less signs of curling. You can see a few more photo period plants there in smaller pots that seem to be doing OK. That don't seemed to have the same problem.

Humidity: Is the low humidity (probably coupled with the high heat) to blame?

Does anyone have any suggestions of what it could be?

I'm an autoflower grower myself and I've seen all kinds of weird leaves on them and the plants turn out different every time - sometimes it's just one main cola really nice and thick together, other times it has a lot of branches out. It could be heat or a number of other things. Right now my plants are growing in an environment hotter than ever and there is no leaf curling like that (CFL lights on 24/7 and up close), but some of my bottom leaves look similar to yours (odd shapes). I'd say humidity and temperatures are the least of your worries. If I had to guess... Maybe leaves "curl up" to reach the light better? My plants turn their leaves towards the lights (when it doesn't shine right above them) and it could alter the leaf structure or something. Don't take my word on it, I'm a new grower too, but I wanted to let you know you are not alone with your problems. Your plants will yield something in the end if you let them be, just try not to kill them yourself (been there, done that). Here's an older thread with the same question: https://www.rollitup.org/general-marijuana-growing/437099-my-leaves-curling-up.htm

look like heat stress.... 80's is high for them babies. that temp is more suitable but not even ideal for older vegging plants

Too hot. Because its too hot the 600w is stressing them.

I have same issue. Plants look extremely similar. My humidity is 20-30%, temp 75F, fox farm soil, perlite and some cocotek. Led light blue and red spectrum. Have good air flow and ventilation. No nutes yet just distilled water. Water every 1-3 days.

Would post a pic but not sure how yet on this..

Anyone know what my problem is?