Its 100% normal. The plant is maturing and dying.

Dont worry, it means the plant is getting ready to die, which it would do in normal outdoor natural life.

Dont cut any off though, it'll just shock the plant, let them drop off.
LIP Reviewed by LIP on . yellowing leaves durring flowering??? i started 3 plants on 4-1 two from clones i aquired from buddys and one seed all were started in oasis cubes and then i moved them into a 80% super soil 20% perilite mixture in one gal nursery pots and then vegged at 18/6 light cycle under cfl lights and given no nutes for three and a half weeks then they were given some 1/2 diluted plant food 24-8-16 twice when they were 12-15 inches i changed the lights to 12/12 to flower they have been flowering for about 2 1/2 weeks and comeing along Rating: 5