What Is 20-20-20 Fertilizer And Can You Use It To Grow Cannabis?


When you decide to grow your cannabis instead of buying it from elsewhere, you need to learn a lot to ensure that your plants grow healthily and successfully. That means you need to ensure that you have the suitable soil for the plant to grow properly, as well as the right fertilizer type. It can be challenging to find the correct fertilizer for growing weed because there are so many variables. Also, when you give your plants fertilizer, you need to ensure that you are using it correctly or backfire.

Giving your plants too much healthy food at once does not always produce favorable results. The same goes for animals and humans eating too many healthy foods in a day because you can experience problems. One comparison is if you eat too many carrots, your skin turns orange. Or, if you overeat roughage, you can end up with diarrhea. So that backs up the saying that even too much of a good thing is not suitable for you at all. Therefore, when using the right fertilizer for your cannabis plants), you must know what you are doing and how much of it you can give to them.

There are various fertilizers, and one of the most common ones you see is the 10-10-10 fertilizer. What about the 20-20-20 fertilizer? Can you use it for cannabis plants? Let’s talk about that further. However, the first thing to do is to go over the 20-20-20 fertilizer.

What Is 20-20-20 Fertilizer?

The 20-20-20 fertilizer is a premium fertilizer, and you can think of it as a high-calorie protein shake needed for working out or for healthy weight gain for those who are ill or for children who undereat. That type of fertilizer is a multi-purpose one that you can use for various stages of plant growth. In some cases, you can use this fertilizer throughout all stages of plant growth. This one has the label 20-20-20 because it contains equal amounts of nitrogen, which is 20 percent, then 20 percent phosphorous, and then 20 percent of potassium. Therefore, nitrogen helps to stimulate vegetative development, whereas potassium and phosphorous promote a robust root system for the plant grow your buds.

You see this fertilizer used on crops that feed heavily, such as onions, corn, tomatoes, cauliflower, kohlrabi, cabbage, and broccoli. That type of fertilizer is also water-soluble and will dissolve quickly, even in cold water. However, unless you have a garden where you are growing those crops, you will not be concerned if the 20-20-20 fertilizer works for them. Does this heavy-duty type work for cannabis plants? Let’s delve into that now.

Can You Use 20-20-20 Fertilizer To Grow Cannabis Plants?

You have to remember that this premium fertilizer is potent, and you will want to talk to experts who specialize in the growth of marijuana plants. However, if you use the 20-20-20 fertilizer safely for your cannabis plants, it can work well. The recommendation is to either use one half of a teaspoon of this fertilizer per gallon and mix it with water once a week or every other feeding. You will want to use this fertilizer during the vegetative state. The vegetative stage is when the rapid growth and development of the plants and roots occur. That is the time when your plants will be “hungry.” Think about a growing teenager or a growing toddler going through a growth spurt. That is when they have to eat all of the time.

Therefore, you can give your marijuana plants 20-20-20 fertilizer when it shows signs of it requiring feeding. However, providing this fertilizer for the plants too often or before the vegetative state can damage them. It can cause your plants to burn. That is the last thing you would want. Many marijuana plant growers have said this premium fertilizer can cause the leaves to burn as they had negative experiences with it. So, if you’re going to use this fertilizer for your weed, be careful. You will also want to keep a close eye on them as they grow and ensure they receive the best care possible.

How Else Can You Care For Your Cannabis Plants?

Growing your cannabis outdoors, you know that your plants require as much natural sunlight as possible. You want to ensure that they are safe from the elements and do not wish pollutants to harm your plants. If you live somewhere warm, then you have the advantage of growing your plants outdoors all year round. If you live somewhere with colder winters and snow, you can learn to grow your cannabis indoors.

The best thing you can do is feed and water your plants at the right time and use the best fertilizer for your cannabis. That means using the 20-20-20 fertilizer when it is appropriate during the vegetative stage. Unfortunately, bad weather will happen even in warmer climates, and cold snaps also occur now that climate change is often occurring. There will also be pests, and it is very little you can do about these issues.

You also want to ensure that where you live is temperate enough not to get too hot or get too cold. The wrong temperature can stunt growth, and it can also harm the chemical structure. That means it will hurt the production of THC. The ideal temperature to grow cannabis outdoors is between 75 Fahrenheit or 23.8 Celcius to 86 Fahrenheit to 30 Celcius. A few days of higher and lower temperatures will not cause a problem, but if it is constant, it will. That is why it may be ideal for growing your cannabis plants in a greenhouse setting since the temperature can be volatile at times.

Recent Studies on Fertilizer Use in Cannabis Cultivation:

  • Optimal Nutrient Concentrations:
    • A study found optimal concentrations of N and P for cannabis in soilless production during the flowering stage to be approximately 194 mg/L and 59 mg/L, respectively. Interestingly, cannabis did not show a significant response to potassium within the tested range, suggesting that the high K levels often used by cultivators might be unnecessary.
  • Impact of Nitrogen Forms:
    • Another significant finding highlights the impact of nitrogen forms on cannabis. The ratio of ammonium (NH4+) to nitrate (NO3-) significantly influences plant function and the biosynthesis of cannabinoids and terpenoids. High NH4+ levels were found to negatively affect these crucial cannabis components, while moderate levels (10-30% NH4+) did not substantially impair plant function but resulted in smaller inflorescences and lower yield compared to NO3- nutrition.
  • Fertilizer Rates and Cannabis Cultivars:
    • Research involving different cannabis cultivars treated with varying fertigation treatments, including a 20-20-20 fertilizer, showed that optimal fertilizer rates observed at 50 ppm N. Increased rates above this led to reduced plant growth, biomass accumulation, and cannabinoid concentrations.


If you are growing cannabis plants‘, you need to know how to care for them and their development. There are various fertilizer types, and you want to ensure that you use the right ones for their growth. The deal is can you use the 20-20-20 fertilizer for cannabis plants? The answer to that is, it depends. You can use diluted amounts for every other feeding during the vegetative stage only. If you use that fertilizer before that stage, you can damage the plant. Many marijuana growers report times that they used premium fertilizer and caused the plants to burn. Therefore, you want to exercise caution while using it.