Can anyone tell me if this is heat stress? I'm using FF Growbig in FF Ocean Forest soil. I have a 1000 watt HPS light for 12 plants, they're still veging. Is this heat stress or have I not been watering them enough? When I've been watering them, I usually don't have run off go to the bottom. So I assume I've probably been under-watering them, I gave them a nice watering and made sure to see run off from each. Lights go off in an hour, hopefully they will be doing better tomorrow morning. Any advice would be nice. The leaves are dry and twisting.
Heat stress can cause that sort of leaf deformation, but so can Phosphorus deficiency. The GB fertilizer is just a little low in P. Whole-plant pics and pics of any other current leaf problems would be helpful in determining which.
I get my taxes next week and plan on ordering a carbon filter/fan and setting up the exhaust, I'll also get tiger bloom and big blossom, so I'll be able to see if it's the P then. I have my 1000 watt HPS light about 26" above the plants tops, since my ventilation isn't properly set up yet. I put my hand at the top of my plants, and my hand doesn't really feel the heat at all. So that's why I'm kind of confused. You said the yellow spotting on my plant before could be related to P.. I just don't have the money until next week, but now the symptoms are different than the spotting, so I'll try to get them some tiger bloom and get that ventilation set up. I have been keeping my growroom door open when the lights have been on, preventing it from getting too hot in there. I guess I've realized that I started the grow without having all the proper stuff I needed, now I got that in-over-my-head feeling. --
Just picked up some big blossom and tiger bloom. So after the soil dries out a little bit, I'll give them some of the tiger bloom, then I'll be able to know if it's the Phosphorus deficiency or not.
It looks like heat stress from the way the upper leaves are cupping and the fact that there aren't any of the tell-tale splotches of necrosis commonly associated with P-def. A little extra P is still a good thing and will prevent actual P-def. The stress is only mild and they look very good otherwise. There could be some of both issues but since more P is on the way, the temperature is the only one left to address.