Nice pic's that help's alot.

My first guess is going to be over-watering.You want the first inch or 2 of soil to be dry before re-watering.What over-watering causes is root rot,weak root's=weak plant.

Dive:stoned:
Divestoned Reviewed by Divestoned on . yellowing at tips then drying up hello im trying to help a freind out whos having problems growing. hes growing in coco soil using coco a and b, hes growing in a tent with 2 400w lamps with the temp at 26C with the lights on 18hrs a day, he used 30ml of coco a and b and 5 ml of bio - stimulant and and the plant started to yellow at the tips so hes been flushing it out for the last 2 weeks with ph water at 6.0 the new shoots are coming green then still yellowing at the tips some curling up then drying n falling of. can anyone Rating: 5