If u r a meticulous grower then u can flush at the beginning of the bloom with a gallon of water mixed with something like clearex. 90% run off. Then a week b4 harvest quit fertilizing and flush again until run off is clear. Leave alone. Pistil color is not the most effective way to tell if your plant is ready, personally I think it is a combo of things like the swelling of the pistils pods and color. But your plants still have time left....feed dem girls.