supergrowplants banner

N-P-K Fertilizer Guide


NPK means Nitrogen-Phosphorous-Potash (Potassium). For example 20-20-20 would be the numbers you see on a package of fertilizer. Thats 20% N, 20% P and 20% K. 5-5-5 would be 5% of each etc. Sometimes you see 30-10-10 which is 30% Nitrogen with only 10% of both Phosphorous and Potash. Something with more Nitrogen is great for the beginning of plant growth. Something with more Phosphorous and Potash is good for the flower or budding stage of plant growth.

N means Nitrogen.
Nitrogen will make your plant green and increase the growth speed. Nitrogen is the most important nutrient at the beginning “vegetative” stage of marijuana plant growth. So when starting your plants choose a fertilizer with more N than P or K.

P means Phosphorus.
Phosphorous helps your plant grow a strong root base, it helps the immune system resist decease. It aids in growing seeds, buds and fruits. So it’s important during the blooming or the “flowering” phase. When you bud your plants choose a fertilizer with more P and K and less N.

K means Potash (Potassium). (its K and not P to avoid confusion)
Potash also aids in root development and growth, it can help a plant during droughts. The immune system is boosted as well. This nutrient goes well with Phosphorus during the “Flowering” phase of marijuana growth. The reason why it’s a K and not a P is because two PP’s in a row would be very confusing. What makes more sense NPK or NPP? NPK can be understood much better right? Yes it can, which is why its NPK and not NPP. Check out some examples of nutrient labels.


This organic natural Alfalfa meal fertilizer contains: 2.5% Nitrogen and 1% of both Phosphorus and Potash


This Miracle Grow contains 20%-20%-20% (N-P-K).



This Advanced Nutrients Bloom bottle contains 0-5-4 NPK and is designed for growing Marijuana.




When selecting the nutrients you want to use for your indoor grow. Keep in mind the meaning of NPK and choose according to your plant and stage of growth. I recommend for better taste and less trouble to grow with ORGANIC fertilizers. When growing with chemical nutrients you can easily overdo it and ruin the taste of the bud. I learned this from experience. Bat Guano, Kelp, Alfalfa Meal, Blood Meal are some examples of ORGANIC nutrients. Visit a hydroponics shop or website for ideas on what is being used for Marijuana growth. Always avoid nutrients from Wal-Mart, Lowes and Home Depot etc. (unless organic) The type of fertilizers they sell are not made for Marijuana but for common flowers or grass.