HighTVanswered grow question 6 years ago Hey there Farmermo! You should flush your plants whenever they show signs of toxicity, Nutrient lockout or right before harvest for a smoother smoke! For best results highly recommend a PH between 6-6.3 when flushing your plants. If you are flushing plants from an toxicity then 3-6 days of flush depending on the severity of the nutrient toxicity will suffice. If you are flushing your plants before harvest I recommend a full week to allow time for the plant to work out all those excess nutrients to make your smoke much much smoother! I hope this helps with your question Farmermo! Feel free to ask anything else you may need 😎