leaves curling under

Hey i got a problem. im using a 400watt HPS and my temps are about 78-81 F and my plants have been doing fine upp till about 5 days ago.. the leaves are very skinny and are curling under and become dry and crispy.. but only some of them.. the bottom leaves are still very nice and n problems.. my babies are in MG soil with no NUTEs so far except tomatoes alive from Gardens Alive idk what to do so can someone help me out.. ive been searching but cant find a good answer

Was also thinking maybe a N deffeciency slightly.. cuase the leaves look like the leaves of a plant thats in its last week of flowering all curled under and stuff.. but no yellow spots or anything

That could be a couple things.
Suffocation... when your plant is in a badly-ventilated grow space you will start to see those 'canoe leaves'.
pH issue... is that PEAT I see in your soil? Looks peaty. Flush the crap out of it. Check your runoff. Adjust your pH if it needs it... and by the looks of things it REALLY needs it.
Good news is that you are not past the point of no return. That plant can be saved.

Stinky is always right about everything.... SO I would listen to her words and take them well.

Since you mentioned you are using MG soil Chances are its a PH thing. You should search for the Thread made by GKnowm about a whole grow he did in MG soil. he had to Ph his water up to 8 for watering (most Tap city wate ris 7)

The Ph of MG soil is very low. So I bet judging by the age of your plant. i bet the Ph is really out of Wack. Since Mg soil has nutrient fertilizer in it already a Flush may help but Im not sure if you'll get it back to where you want to be Ph 6.8

Check out that Thread dude,, And do the things Stinky suggests...

Good Luck

kd

I dont think its my temperature because its about 78-81 with a thermometer and i have a fan blowing fresh air in and a fan blowing air out.. so i dont think the air is a problem and i got rid of the MG soil and i transplanted them into some plain soil that has worm castings and bat guano and perlite.. figured that would be the best... see how theyre doing in the morning.. but i think my one plant the sicker of the two is showing its sex.. im pretty sure those are pistils.. let me know what you think and thanks for all the responses guys

that is nute burn...whenever you see tips burning up...your nute s trenght is too high. bad ph can lead to similar problem, but you wouoldn't see the burnt tips. you could've just flushed with ph6.5 water 3x the amount of the pot. i.e. 1 gallon=flush with 3 gallons

personally. I think you ar ein a dangerous area, and better watch them closely.

To accurately check ph from a potted plant...water thoroughly, then check the runoff after 10-15 minutes. I have never had to adjust my water much for soil plants. I also do not believe that miracle gro potting soil ph is way off. If that were true, no-one would be able to grow anything with miracle gro; and although I wouldn't grow pot in miracle gro soil...that just isn't so. peace