fan leaves curling

my fan leaves on my plants (which is three weeks into flowering) are being to start to wilt however the small ones around the budding sites are fine - is this a normal part of the plant cycle

are the leaves curling up or down? if there curlin down, they either need more water or it is too hot in the grow room.

curling down however the smaller ones on the bud sites are fine

The fan leaves do turn yellow and die during the flowering stage .... If the bud leaves look good I would be too concerned ...