Cannabis Growing Cannabis

Best Nutrients and Fertilizers for Each Cannabis Growing Stage

When it comes to growing cannabis, one of the most important things that you have to do is to provide your plants with the proper fertilizers and nutrients.

Without the proper nutrients and fertilizers, your cannabis plants will likely not produce very high yields or big buds, and in the worst-case scenario, might not survive.

Without the proper types of nutrients and fertilizers, your plant will not have the fuel it needs to perform various functions required for growth, such as photosynthesis, protein synthesis, and much more.

Just like the human body has various processes that are required for growth and survival, so do plants. Moreover, just like humans need various vitamins and minerals for these processes to function properly, so do plants.

You might be familiar with the big three nutrients that cannabis plants need, known as the NPK nutrients, or nitrogen, potassium, and phosphorus. However, these are by far not the only nutrients that cannabis plants require, something we will touch on in much greater detail further below.

What we are here to do today is to talk about all of the best nutrients and fertilizers that your cannabis plants will need in each of the main growing stages.

We will address the best types of nutrients, as well as some great products, to use during the seedling stage, vegetative stage, and flowering stage of marijuana plants. We’re going to teach you all about cannabis nutrient basics, nutrient ratios, trace nutrients, nutrient deficiencies, secondary nutrients and everything in between that you need to know to achieve fast and healthy plant growth. Let’s talk marijuana nutrients!

Cannabis Plants and Essential Nutrients

The first thing you need to know is what all of the different nutrients are that cannabis plants require, and we’re going to start with the big three, the NPK nutrients.

NPK Nutrients – The Big Three

By far the most important nutrients that your cannabis plants require are the big three macro nutrients, the NPK nutrients, which are nitrogen, potassium, and phosphorus.


First we have nitrogen, which is an essential nutrient for vegetative growth. Your cannabis plants require nutrients to grow big in thick stems, for big fan and sugar leaf production, and for overall plant health.

Nitrogen allows your plant to grow big foliage, therefore allowing you to perform more photosynthesis, especially during the flowering stage later on.

The more vegetation your cannabis plants have, the better they can perform photosynthesis, and the bigger they will grow at the end of the day. A nitrogen deficiency can spell disaster for cannabis growers as it results in limited plant growth.


We then have phosphorus, which to a certain degree is required in the vegetative state, particularly for root development. Phosphorus allows your cannabis plant to properly develop its roots, which ultimately leads to your cannabis plant being able to much better absorb nutrients.

A healthy root system is absolutely vital to the overall health and growth of your cannabis plant. Phosphorus is however even more important for the flowering stage of your cannabis plant.

Phosphorus is very important for the development of big and potent marijuana buds or flowers. Phosphorus is also an essential element for energy transfer inside of the plant, which means that phosphorus is required to turn fuel sources into the food that your plant needs to grow.


Third, we then have potassium, which is an extremely important nutrient, particularly during the flowering stage.

Potassium aids in a wide variety of physiological processes, including, but not limited to enzyme activation and nutrient uptake. It’s just a very important nutrient for the overall health and vitality of your cannabis plants. Technically a plant requires this during every growth stage. This is one of the most important primary nutrients of all!

Other Important Macro Nutrients

While the above nutrients that we’ve talked about are considered the most important ones, the big three, there are other macro nutrients that cannabis plants require to survive.


One of the other very important macro nutrients is calcium, a mineral that is required for cannabis cell wall structure. Every single cell in your cannabis plant requires calcium.

Furthermore, calcium is also an essential element that plays a role in the development of the root system of your plant. Due to its importance in the development of a healthy root system, getting enough calcium into your cannabis plant during the vegetative state is quite important. It’s all about nutrient availability and nutrient absorption.

We already discussed just how important that root system is, so a lack of calcium can spell disaster for your cannabis plants on that note, calcium is also responsible for new transporting nutrients around your cannabis plants.


Next, we have magnesium, yet another mineral that is very important for your weed plant, and another important part of the cannabis plants makeup. In fact, magnesium is an important part of chlorophyll, which is an essential element of every plant that is required to perform photosynthesis.

Photosynthesis is when the plant absorbs sunlight and uses that two turn various sources of fuel into the sugars and other foods it requires to grow. If your cannabis plant cannot perform photosynthesis, then it cannot grow at all.


Yes, sulfur is another important nutrient, a vital component of plant nutrition that you need to provide your cannabis plants with. Sulfur is an essential part of amino acids and enzymes, and it is very important for the overall health of your plant, especially as far as protein synthesis is concerned.


The other important micronutrient that your cannabis plant requires is iron, which is essential for a variety of enzymatic processes and for the formation of chlorophyll.

Vital Micronutrients

Besides all of those macro nutrients, there are then also many micronutrients that cannabis plants require to survive. Let’s take a quick look at these.

  • Manganese is required for nitrogen metabolism and enzyme activation.
  • Boron is crucial for calcium uptake, flour development, and cell wall formation.
  • Your cannabis plants require copper to aid in respiration, photosynthesis, and enzyme activation.
  • Zinc is required by cannabis plants for auxin synthesis, protein synthesis, and enzyme function.
  • Enzyme activity and nitrogen fixation in cannabis plants depends partly on molybdenum.
  • Nickel is yet another important micronutrient that cannabis plants require for enzyme activation and nitrogen metabolism.

Important Cannabis Nutrients for the Vegetative Stage

During the vegetative stage, there are a variety of crucial nutrients that your cannabis plant requires to properly grow. Perhaps the most important of all is nitrogen, which promotes photosynthesis, and the growth of leafy green foliage, as well as strong stems and branches.

Nitrogen is all about providing your plant with the robust and sturdy structure it needs to prepare itself for the flowering phase. Other vital nutrients required for the vegetative stage include phosphorus, potassium, calcium, sulfur, iron, and magnesium.

Best NPK Nutrient Ratios for Vegetating Cannabis

As mentioned above, the nutrient requirements for cannabis plants are different during the vegetative stage than during the flowering stage. This means that you need to provide them with not only the right nutrients, but the right amounts of them as well.

The two most commonly recommended NPK ratios for vegetating cannabis plants are 2:1:2 or 3:1:2.

This means that the fertilizer or nutrient mix in question contains a relatively high amount of nitrogen, a low amount of potassium, and a moderate amount of phosphorus.

Remember, during the vegetative stage, nitrogen is perhaps the most important component of all. It’s important that you don’t give your plant excess nutrients, or else you may cause cannabis nutrient burn, something that everyone will have to figure out on their cannabis cultivation journey.

Most Important Organic Nutrients for Flowering Stage

If we are talking about the most important cannabis nutrients for the flowering stage, there are two that are more important than any others, and these are phosphorus and potassium.

Once again, phosphorus is required for flower formation, bud development, and energy transfer, with potassium being responsible for enzyme activation, carbohydrate metabolism, nutrient transport, and more.

Realistically, during the flowering stage, your plant won’t need as much nitrogen anymore, but still a small amount. All of the nutrients that we have discussed so far today are vital to the health and growth of your cannabis plant in their own ways.

Best NPK Ratio for Flowering Cannabis

Just like during the vegetative stage, your cannabis plant also requires the proper ratio of the big three nutrients during the flowering stage.

Generally speaking, the two most commonly accepted NPK ratios that are considered ideal for cannabis flowering are 1:4:4 and 1:3:3.

This means that the nutrients are fertilizers in question contain even amounts of phosphorus and potassium, compared to very low amounts of nitrogen.

Nutrients During Cannabis Plant Flushing

Something we do quickly want to touch on is flushing your cannabis plant. Flushing of the cannabis plant occurs about two weeks before it is time to harvest the plant.

This process refers to providing your plant with pH balanced water that is free of any and all nutrients and fertilizers.

The point of this process is to flush out all nutrients from the cannabis plant, so that there are none left when it comes time to harvest. Of course, this means that during these last two weeks, you should not be using any such fertilizers or nutrients at all.

The Best Nutrients for Cannabis for all Stages

Now that we have the basics down about the different types and levels of nutrients that your cannabis plants require, let’s take a closer look at some actual products that you can choose to go with.  

We’ll first start off by talking about the right soil and nutrients to use for seedlings, followed by the best fertilizers and nutrients for cannabis plants in the vegetative stage, and finally the best ones for plants in the flowering stage.

Best Nutrients for Seedlings: High-Quality Potting Soil

When you are first starting out with your cannabis plants, one of the most important things to remember is that seedlings don’t really require many nutrients.

In fact, all of the nutrients that your seedling cannabis plants get should come from high quality potting soil, not from liquid or powdered fertilizers or nutrient solutions.

Seedlings are very delicate and fragile, and they really can’t handle all that many nutrients at all. If you provide seedlings with too many nutrients, which realistically isn’t that many, you will burn them, and ultimately kill them.

Too many nutrients result in what is known as nutrient burn, and generally the death of your plants, and if you aren’t careful, this can also happen to adult plants too. Although, seedlings are much more delicate, so this is very important to pay attention to here for the first few weeks of growth.

Once again, the only nutrients your cannabis seedlings require will come from high quality potting soil, and you even need to be careful with that, because some parking size also contained way too many nutrients.

High-Quality Potting Soil

One of our favorite products on this front is this Mother Earth Terracraft Potting Soil. This particular very high quality potting soil is formulated with a wide variety of nutrients to provide your cannabis plants with the fuel it needs to get started.

With an NPK ratio of 0.19, 0.08, and 0.11, it provides your seedlings with the perfect starting point, especially because it has a decent amount of nitrogen compared to the other two elements.

However, the good part about this soil is that it does not contain so many nutrients that it will burn the seedlings.

Furthermore, these nutrients are also slow release, so you won’t have to fertilize your plants for at least a few weeks. What’s also nice is that this soil is said to be ideal for both indoor and outdoor use, plus it is ready to go right out of the bag.

One of the biggest benefits that you get with this soil is that it is formulated with peat Moss, pearlite, earthworm castings, and forest products. These elements come together to allow for greater drainage and aeration capabilities, so the soil doesn’t dry out too fast and so that your plant roots don’t rot either.

These elements, especially the earthworm castings and peat Moss, also contain vital macro and micronutrients that your cannabis plants need to survive.

Rooting Solutions

Before we move on to talking about the best nutrients for cannabis plants in the vegetative stage, we do want to touch on the roots of your seedling.

Once again, the roots of your cannabis plant are extremely important. After all, the roots are like the anchors that hold the plant down in the soil. Furthermore, the roots are the components of your plant that take up nutrients and water.

Without a healthy root system, your cannabis plants just can’t survive. Therefore, many people decide to use what are known as rooting solutions.

These are special products that contain a variety of ingredients, such as vitamin B1 for instance, that have the ability to increase the healthy growth of plant roots, both in terms of growth rate and size.

What is also really neat about a product such as the Hormex Rooting Solution, is that it is also specially designed to prevent transplant shock and stress from occurring in your plants. Overall, this is one of the best products at your disposal to help your cannabis plants develop healthy root systems.

Best Organic Fertilizers for Cannabis Plants in Vegetative Stage

Now that you know what kind of cannabis nutrients and potting soil are best for cannabis plant seedlings, let’s take a closer look at what some of the best options at your disposal are for the best nutrients for cannabis plants that are in their vegetative stage.

Once again, remember that during the vegetative state, your cannabis plants require high levels of new nitrogen, low levels of potassium, and moderate levels of phosphorus. Therefore, any type of nutrient solution or fertilizer you get for your cannabis plants need to reflect this requirement.

Liquid Nutrients – NPKs

Even with high quality potting soil, after about two or three weeks, those plants in the vegetative stage will require additional cannabis nutrients. Here we have the Grow Big Liquid Plant Food Solution from Fox Farms.

This is by far one of our favorite products to use, and for good reason. These are some of the best cannabis nutrients available for helping to prevent a nutrient deficiency. These are some super advanced nutrients made with organic compounds!

First and foremost, this is a concentrate that comes in at a reasonable price, which means that a little bit goes a long way, and it’s very cost effective as well. This particular liquid plant food has the adequate NPK ratio to grow cannabis plants during the vegetative stage.

The NPK ratio here is 6:4:4, which as you can tell is pretty good for vegetative growth, especially due to the relatively high nitrogen content.

Even better is that this product also comes complete with some earthworm castings, other micronutrients, and Norwegian kelp, all of which help to support the healthy growth and development of your cannabis plant in their own ways.

If you need your cannabis plant to grow big and lush foliage, so those fan leaves can absorb plenty of sunlight to grow big buds, then this is a fantastic product to consider.

Liquid Macronutrients

Unfortunately, even the best liquid fertilizers for vegetative growth in cannabis plants often don’t contain enough micronutrients, particularly calcium and magnesium. This is why we have also chosen to include this product, Fox Farm Bush Doctor Cal-Mag on the list. This is by far one of the best cannabis nutrients out there, but keep in mind that hydroponic nutrients for cannabis are a bit different.

Both of these cannabis nutrients together help to support healthy root growth and vegetative growth. It contains 3% calcium and 0.9% magnesium, which should be more than enough to allow for great vegetative and foliage growth. This product also supplies your plants with essential nutrients, organic nutrients, which help to improve nutrient uptake.

Furthermore, it also has an NPK ratio of 1:0:0, so it does also provide your plants with a bit of nitrogen. Interestingly enough, this is also a product that can be used during the flowering process, as it should also help in the development of large and healthy buds. Remember to not use too much however, or else you may cause cannabis nutrient burns.

Best Nutrients for Cannabis Plants in Flowering Stage

Remember that cannabis plants in their flowering stage require a whole lot of potassium and phosphorus. These are the most important cannabis nutrients at this time. These are by far the two most important nutrients that your cannabis plant needs in order to grow big and healthy buds. Let’s take a quick look at some nutrients that will help on this front.

NPK Powder Nutrients

One of our favorite products as far as cannabis nutrients for flowering cannabis plants are concerned is Beastie Bloomz, which contains an NPK ratio of 0:50:30. Yes, as you can tell, this product is extremely strong and contains insane levels of both potassium and phosphorus, which means that a little bit goes a long way. It provides your plants with essential nutrients to help prevent a nutrient deficiency from occurring.

Remember that this is a powder product that you mix in with your watering solution, so be sure to test the pH level first. Either way, this is part one of the best fertilizers that you could possibly get for a flowering cannabis plant.

Tips for Fertilizing Cannabis Plants

  • Once every few weeks, flush the soil with pH balanced water that is totally clean and free of nutrients. This will help reset the nutrient balance and remove excess salt from the soil.
  • If you are unsure if the nutrient solution you are using is too strong, you can always start with a much lower concentration and then gradually increase it.
  • Always follow the recommended dosage on your product and never use more than is recommended, or else you may cause a nutrient burn.
  • Make sure that you always test your nutrient solution for pH levels. Remember that for soil, the pH level should be just slightly acidic.
  • Always keep a close eye on your plants to see how they are reacting. Always look for signs of nutrient deficiencies or nutrient excesses, and then make adjustments as needed.
  • Always stop fertilizing your plants during the last two weeks of growth, as this is the flushing period. This is when you need to give your plant just plain water to remove any nutrients that remain, so the plant is then ready for harvest.
  • If you are using various nutrient sources, make sure to rotate them so that your plant gets an even mix of everything.


You should now know quite literally everything there is to know about the nutrient requirements that your cannabis plants have, and this is the case for all stages of growth.

Remember to start off with some high-quality potting soil and then provide your cannabis plants with the adequate nutrients for both the vegetative and the flowering stages.

If you follow all of the tips and rules that we have provided here today, getting big cannabis plants with high yields should not be a problem.

Fabian Raemy is an avid cannabis enthusiast and expert. He's been a part of the cannabis community in one way or another for the past 15 years. Whether cultivating or consuming, Fabian knows his cannabis inside out. In his humble opinion, there’s just nothing more rewarding than growing a great strain of marijuana and being able to take a puff of some home grown green.

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