It is a heat and or air related issue. The leaves are having trouble breathing. It's kind of like a air in air out thing, and the plant is having trouble due to haat(maybe from the light too close or temps too high), and this can also be caused by lack of air movement. This will get worse if not fixed, and you will end up with taco leaves.

Cheers,
niles007 Reviewed by niles007 on . more problem pics. ok folks, these pics are of my train wreck plant with leaf curling. so far ive got four answers for this problem. 1- heat from lite. 2- PH problem. 3-magnesium defishontcy. 4-roots exposed to lite. i am very thankfull for all replys. but who is right? the problem started at the top of the plant and spreading downward,also spreading to new growth:confused: thanks again. Rating: 5