whats mean when leaf turn up

same as title

The answer to your question will most likely be found here...

not much info always willing to help but dam some pics or something more than your title would be nice but anyway most likely heat stress but couldnt tell you for sure.

fairly impossible to tell u without any pics or more info, BUT having said that, the most common reason would be a lack of magnesium (common in indoor plants) & the plants turning up signal they r "praying for magnesium". supplement about 2 tsps epsom salts per gallon to ur watering schedule or go to ur hydro store & get calmag or similar which is a dual calcium/magnesium supplement.

or, depending on the light ur using, it could be ur plants r "reaching" for the light, if it is not close enough. for instance cfl lights u should have less then 2 inches above ur plant the entire grow.

Too much heat.
Your light may be too close to plant