DrGanjanswered grow question 4 years ago You've burned out your chlorophyll most likely mate. Not much chance of getting it back now. However, if it's your whole plant yellowing, it could be a nitrogen deficiency which can be quickly amended using a foliar feed. (can use some veg nutes at 1/5th the dosage you would usually use or can buy special stress treatments such as Madame Grow Lavacal Stress Treatment)