leaves curling ?

hi my leaves are curling on up one down what is the plant asking for the leaves are dark i have watered quite a bit as the temp was high and drying them out too quick and some of the plants died off this , and i have watered and lowered the temp what should i do ?

What us your lighting system?
Watering schedule?

got da same prob but one of da plants fan leaves are really small and crystle looking in vegg and its dark green the fan leaves have 5 fingers too its weird im wondering about this too and i reduced the fert on all the others and give correct ph and room temp is at 80 and all the other plants had got better..but except that one plant ...