Northern lights auto

High, you do not need to do a test! of course it is safe to use, cannabis plants need phosphorus (P) and potassium (K) during the entire flowering phase. Check your bloom nutrients it will say the minerals inside the bottle, it will contain a certain ratio with phosphorus (P) and potassium (K) and Calcium & Magnesium. Cannabis plants need phosphorus (P) during early flowering (first 4 weeks) and from when the buds really start to swell till harvest (last 4 weeks) they need potassium (K), calcium and magnesium. So when you want really good results it is better to use 3 products instead of just using a pk booster like pk 13/14 it is better to use a P booster during the early flowering phase and K booster during the late flowering phase and a Cal-Mag supplement to harden up those buds. When you only want to use a pk booster like pk 13/14 then keep the dosage low because otherwise you will create nutrient lockout due to minerals that the plant will not use and end up as build up salts running up the EC value in the soil. With autoflowers keep the EC around 1.5 from early flower till harvest. Enjoy your grow!