I'm still suffering from the same issue, but they seem slightly better after a few days. I noticed that some of the stems had purple veins on them which I had never noticed before. The veins where not uniform across the plants and since I am using bag seed from maybe 4 or 5 different bags, there is no way that it is a genetic issue with respect to showing purple veins. It would seem that floppy wrinkled leaves, soft stems and purple veins would be a Phosphorus issue. As I was reading up on phosphorus lock out it started to fit more and more. Apparently P gets locked out at ph's of 6+ and I regularly check my ph to find it at 6.5 or so. Then I bring it back down to about 5.8 max before stopping. I think that since my water tends to regularly sit at 6+ ph that it was enabling a P lockout when the cold hit. Apparently P gets locked out in other ways as well including temps in the 50's. Since my grow is in the garage closet the temps can jump around when the lights are out. With lights on, temps are easy to control with fans and such, but when light go out, those same fans are on when they don't need to be in terms of temp. The temps are lowering and several times I have discovered the temps around the plants to be in the 50's. There must have been at least one occasion or more, that the temps dipped low enough during lights out to lock out the P with the addition of the PH being a little too high.

I chanced across a pic that showed a dried up leaf with the last 1/4 of the tips still plush and green while the beginning and middle part of the leaf are completely dried up. This according to that site was a sure sign of P lock out and as I mentioned in other posts, I have one plants with 1 set of leaves that look like that.

Additionally, I have been debating back and forth on whether or not to use my fogger still. I developed some mold on several stems which told me that the humidity was out of control. I turned the fogger off a few days ago and raised the water level significantly in an effort to meet the lower roots on my younger plants. When my older plants finally grew enough roots to touch the res, they shot up like monsters, which is why I raised the water level. So for a few days at least the plants did not have access to fog. No biggie really, except that if I'm not going to use fog, my ppm's need to be much much higher. Apparently somebody forgot to tell me that I needed to be raising ppm's each week. Several months ago I had such an issue with burning tips since I was using nothing but fog, that it scared me off of high ppm's. This also led to P deficiency I think.

On at least one occasion last week, I saw a nice bloom of leaves that all came in yellow. For some reason that didn't register like it should have with me and tell me my ppm's were way to low. With the mix of 3 week and 8 week old plants, I cant seem to keep one set of plants happy while not pissing off another set. All of this leads me to the realization that it's a terrible idea to have different aged plants in the same res especially when they are aged so far apart like mine are.

So last night I dumped in a bunch of fresh ferts and added in a little bit of the bloom nutes as well to help bring P up. I am starting to see a difference. I doubt I will be able to recover the damaged leaves as they are so twisted, dried and still green oddly enough. The newer growth is starting to stand mighty tall again which is encouraging.

I know to some degree cold is causing me issues, but I am still confident that they can survive 55 degree weather. I have other plants in my garage that are handling the colder weather fine. I get this is a different plant though and may not be able to handle 50+ degree weather or at the very least these unknown strains cant handle it. I need to figure out how to put a small heater triggered by a thermometer somehow.

Currently, my ph is under 6, ppm's are at about 450 and I am using my fogger now for 1 minute out of 10 and my misters are 15 on and 15 off. I also dumped in a little extra bloom ferts for the P increase.

Sound like I'm on the right track finally?