Cannabis Nutrition: What are Macronutrients

Macronutrients are the main elements a cannabis plant needs to grow and bloom, they’re widely known by growers as NPK.
Author Enzo Schillaci
08 June 2020
6 min read
Cannabis Nutrition: What are Macronutrients


Like all other plants, cannabis needs nutrients to survive. These minerals are needed in different amounts, the ones needed in higher amounts are called macronutrients and the ones needed in lower amounts are called micronutrients.

Regardless of the amount, both of them are essential to your plant's growth.

1. Nutrients In Cannabis

Cannabis are living beings, and like all of us, they need food to grow. The food (aka nutrients) are delivered when you water them, through the medium they’re in. This means you’re in complete control of when and what they absorb and this is the main cause of deficiencies.

Providing the correct amount of nutrients for each stage of your plant’s life cycle is the best way to avoid not only deficiencies but every other problem that can come along with it.

If done correctly, the roots will absorb and transport the nutrients all the way to the top of the plant, where the new growth is developing. But for this to be done properly and efficiently, you must maintain the correct pH level.

2. What Are Macronutrients?

Macronutrients are essential to your plant’s health. They are the most needed throughout your plant's life cycle and can be classified in primary and secondary. 

Without them, it would be impossible for your plant to fully develop and she would die as soon as the first couple of true leaves grow.

This is why you need to provide the correct amount and adjust it for the different stages. The ratio of NPK should be adjusted for each specific strain, but a general guideline is 2-1-3 for vegetative growth and 1-2-3 for flowering.

3. Primary Macronutrients

The letters NPK stand for Nitrogen (N), Phosphorus (P) and Potassium (K), these are the primary nutrients a cannabis plant needs to perform the basic functions for plant growth.

They are essential for your plant's health and should always be added to the solution you’re feeding your plants.

Nitrogen (N)

Nitrogen is considered the most important macronutrient of all. 


Nitrogen (N) gives your plant the green color, allowing it to produce essential for growth sugars.

This nutrient is needed to absorb light and it is what gives the green color, allowing your plant to produce sugars essential for growth.

Phosphorus (P)

Phosphorus is another very important element because it is a primary macronutrient, it is essential for development.


Phosphorus (P) is essential for development of your plant.

This mineral is essential for respiration, energy storage and it is responsible for allowing the plant to create and copy its DNA to the new cells of the plant.

Potassium (K)

Potassium is a crucial mineral in photosynthesis, this mineral allows the plant to “breath”.


Potassium (K) helps to regulate photosynthesis allowing your plant to “breath”.

By opening and closing the tiny pores in the leaves, it regulates the oxygen that comes out and the CO2 that goes in, an essential process in photosynthesis.

4. Secondary Macronutrients

The secondary macronutrients are Calcium (Ca), Magnesium (Mg), and Sulfur (S). They are also used in abundance by the cannabis plant, but unlike the primary macronutrients, secondary nutrients are used in the structure of the plants.

These nutrients can be found in tap water because it will collect minerals when it travels through the metal pipes until it reaches you. Have in mind they will not be present everywhere, as every country has different ways to treat water so sometimes you will have to provide them yourself.

Also, remember that by filtering the water you will remove all the minerals in it, so you will have to add them to your solution.  

Calcium (Ca)

Calcium is very important in the structure of the cannabis plant. This mineral is crucial for developing the cell walls and membranes of the cells.

Also, Calcium is responsible for allowing them to communicate so the plant can respond to the environment.


The secondary macronutrients: Calcium (Ca), Magnesium (Mg), and Sulfur (S).

Magnesium (Mg)

Magnesium is the most important secondary macronutrient. 

This mineral is responsible for powering the chlorophyll molecule, without it the plant wouldn’t be able to absorb the light energy.

Sulfur (S)

Sulfur is responsible for the formation of proteins, molecules and it’s responsible for the structure of hormones, enzymes, and cell membranes.

5. Recommended Amounts Of Macronutrients 

Although the proper amount of macronutrients can vary from strain to strain, here is a general guideline for new growers.

Have in mind the amounts shown should be adjusted in response to the signs your plant gives and the stage she’s in.


These recommended amounts of macronutrients will vary depending on the stage your plant is in.

Note: These numbers represent the ppm value for all the cannabis life cycle and should be adjusted according to the signs your plant gives.

6. Overfeeding and Underfeeding

As said above, the chart is a general guideline and can vary from one strain to another. The only way to measure particles per million (ppm) is by measuring the Total Dissolved Solids (TDS) with a TDS meter


TDS meter allows you to measure the Total Dissolved Solids.

This means that if you don’t have a TDS meter, you won’t be able to measure the number of nutrients your solution has and it can cause overfeeding or underfeeding, both resulting in different signs of nutrient deficiencies.

Because of this, the best way to feed, if you don’t have a way to measure, is to start feeding lightly, see how your plant reacts (if she’s still hungry or not), and adjust according to the signs she gives.

7. In Conclusion

Macronutrients are the most abundant and needed minerals in the life cycle of a cannabis plant. Those minerals are like food for humans, they need it to produce energy and develop properly. And just like us, some plants eat more than others, resulting in a bigger plant and quicker development.

If you’re new to growing, it is better to start with a resistant strain that takes a lot of nutrients easily, for this case we recommend our new Gorilla Cookie Auto. 

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She can take a big feeding especially from week 3 and onwards, making it hard for new growers to overfeed her.

Make sure to start feeding your plant a small dose of nutrients to see how she reacts to it and then adjust accordingly.

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