What’s the Best NPK Ratio for Cannabis Nutrients?
This picture shows an example of a full nutrients lineup for growing cannabis. This shows nutrients and supplements by General Hydroponics. Although supplements are nice, you can get all the way to the end of your grow without using any! Your base nutrients is all you need!
If you’ve decided to start growing cannabis for the first time, trying to figure out the best nutrients for your setup can be very confusing. There are many nutrient companies, and each one creates multiple types of nutrients with different purposes.
The most important thing is to make sure you give your plants the right amounts of nutrients at the right time. There are two main life stages for cannabis plants, and each stage has different nutrient requirements.
For the best results, your cannabis needs the following nutrient ratios….
Chart diagram showing the optimal NPK nutrient ratios for growing cannabis or medical marijuana
Where is this information? Most nutrient bottles display 3 numbers, often called N-P-K, which stands for Nitrogen, Phosphorus and Potassium
Most cannabis nutrient bottles prominently display 3 numbers, called “NPK” which stands for Nitrogen, Phosphorus and Potassium. These numbers tell you the ratio between each of these nutrients in the bottle
Why “K” for Potassium? The atomic symbol of Potassium is “K” from Neo-Latin kalium.
In other words, you want to use a “Vegetative” (high Nitrogen) or “general purpose” nutrient formula for the first stage of life known as the vegetative stage. If using high-quality soil, you can skip vegetative nutrients for the first 3-4 weeks while your plant uses up the nutrients in the soil, otherwise you should start with vegetative nutrients around the time your plant opens its first leaves.
Example of healthy green cannabis plants in the vegetative stage. At this phase of life, cannabis only grows stems and leaves, which requires a lot of Nitrogen!
Use a “Bloom” (low Nitrogen) nutrient formula with plenty of P & K for the flowering stage. Start using bloom nutrients when buds start forming to make sure your plant gets plenty of Phosphorus & Potassium, which are crucial to bud development.
Phosphorus tends to increase the number of flowers, while Potassium helps increase the bulk/weight of flowers. Be careful, though because going overboard with either one can burn your plants!
The main thing is to avoid giving too much Nitrogen in the flowering stage, as it can discourage bud development in the flowering stage and add an unpleasant taste to buds, which is why a general purpose plant nutrient isn’t a good choice in the flowering stage.
Get Cactus nutrients on Amazon.com! Although maybe not ideal, this will work well in a pinch if you can’t find any other flowering nutrients for your marijuana plants.
In a pinch, nutrients for “cactus” or “succulents” can be used in the flowering stage until you get better nutrients because they usually have low amounts of N and plenty of P & K.
Note: Don’t use any type of time-released nutrients (like fertilizer spikes, or “slow release” Miracle-Gro soil) because they deliver too much N in the flowering stage and may reduce bud growth.
Cannabis needs plenty of P & K to make buds in the flowering stage!
Example of a cannabis plant in the flowering stage, growing big fat buds. In order to get the best yields, you need to use flowering nutrients that contain lots of P and K, but low levels of N
The Best Cannabis Nutrients Aren’t Enough! Check the pH of your water to plants to prevent deficiencies
HI 98127 – A digital pH tester by Hanna Instruments – Get one on Amazon.com!
It may surprise you that the most common reason growers get nutrient deficiencies is because the pH is too high or too low. This happens even if the right amounts of nutrients are present, because your weed simply cannot absorb the nutrients if the pH isn’t in the correct range.
Optimum cannabis pH for..
Soil: 6.0 – 7.0
Coco Coir: 5.5 – 6.5
Hydroponics: 5.5 – 6.5
Checking the pH will make a huge difference to your grow by keeping plants vibrant and healthy. It only takes a few minutes each time you water your plants! If you get a digital pH pen, it only takes seconds to test your pH!