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The Nutrients to Feed Cannabis During Flower

Ultimately, healthy flowers are what all of us are after with a cannabis grow. You’ve got the consider your growing environment – your soil, your lights. But which are the nutrients to feed your plant during the flowering stage?

These are the ones to focus on. Getting them right will reap incredible benefits.


There are people who think nitrogen isn’t a top nutrient when the plant is in flower. But this is not the case.

Nitrogen helps build cell walls. Though it’s true that nitrogen is more utilized during the vegetative stage when the plant is building the cell walls of the whole plant (including the leaves) you have to remember that when you initially switch your lights to a 12/12 light schedule (some may do an 11/13 light schedule) and you start that initial feeding for the start of bloom; the plant is actually going to need a slight boost of nitrogen, during the stretch phase.

The stretch phase can begin anywhere from three days to one week after changing your light schedule to a shorter one. Once the plant realizes it’s time to start focusing on going into flower, it will focus on extending the trunk closer to the light, developing more sites for flowers to grow.

nutrients cannabis

While in this stage, it will use up its own nitrogen reserves. So, if you don’t have the extra nitrogen to replace the extra used, you may run into deficiencies that could affect yield and flower production.

Then, as the plant progresses, it will still need that extra nitrogen to develop the flowers and even the sugar leaves. Nitrogen will also aid in the overall production of trichomes as well.


  • Nitrogen helps build cell walls
  • During the stretch phase, cannabis likes an extra boost of nitrogen
  • Add nitrogen during flowering phase to help fill up its reserves
  • Nitrogen contributes to trichome production as well

Phosphorus and Potassium

These two are grouped together as they’re the two primary nutrients people think of when it comes to flipping their cannabis into the regenerative (flower) cycle.

You can think of using these as the opposite of nitrogen. Where nitrogen is used more during the vegetative stage, phosphorus and potassium are used more in the regenerative stage (but should still be used in the vegetative stage).

You’d want to use these during the veg stage because the plant will not only use them for cell and site development, it will also store those nutrients for when it is ready to transition into the regenerative stage.

Even though I lump these two together, they do play two completely different roles in the plant’s development. Phosphorus is closely tied to bud development, more, bud density, and size. In the vegetative stage, it will help create more sites that can produce flowers. When you flip into the regenerative stage, you want to boost phosphorus levels, especially during the stretch. The plant will be able to send the phosphorus to those bud sites.

nutrients cannabis

If the plant has an abundance of phosphorus, it will produce nice, thick, fragrant flowers. They do this to attract pollinating insects, at the same time, deter things that can cause them harm.

As for potassium, you want to try and keep a decent supply throughout the plant’s life.


Potassium acts as a regulator, like a bouncer at a nightclub. It does this through a process known as osmoregulation – regulating water and salts by controlling the opening and closing of the stomata (stomata are the pores or the “mouths” of the leaves).

With proper potassium, the exchange of water, salts, oxygen, and CO2 is regulated for maximum productivity inside the plant.

Potassium will also trigger the production of a chemical called Adenosine Triphosphate (ATP). ATP stores energy within the cell since it is a 5-sugar carbon. When it is ready to be used, it breaks down to ADP (remove the ‘tri’ from the ‘triphosphate’), which is then released as energy for endergonic reactions (changing one element into another, so the plant can actively use it). This is very important, not only to produce flowers but the production of cannabinoids and trichomes.

The better development of those two, the higher the concentration of THC and cannabinoids.


  • Phosphorus and potassium are used more in the regenerative stage
  • Phosphorus is closely tied to bud development
  • Potassium acts as a regulator, like a bouncer at a nightclub
  • With proper potassium, the exchange of water, salts, oxygen, and CO2 is regulated for maximum productivity inside the plant.

Calcium and Magnesium

Both are the most common causes of deficiencies, so getting your levels right is crucial

When fed to the plant, the magnesium will help carry the calcium to the right place. These are also used pretty heavily throughout the plant’s life. You will need to give more when you transition your plant into the regenerative stage to help with not only the stretch of the plant but the bud development as well.

Calcium, like in humans, is responsible for maintaining cellular structure. Give too much; you can stunt your plant’s growth. Give too little; your plant will start to wilt, developing rusty spots on the leaves.

You want to maintain a healthy balance with calcium. The stronger the cell wall, the tougher the plant. This means better resistance to disease, bacteria, and fungus as well. Think of it like a gate around a building. A strong gate will keep out the things unwanted by the plant but will have the ability to better regulate the things it wants.

nutrients cannabis

Magnesium, on the other hand, produces the energy for the plant to either grow during the vegetative stage or grow flowers during the regenerative stage. It is the energy powerhouse in the chlorophyll of the plant.

Without enough magnesium, you won’t have enough energy for photosynthesis (the breakdown of sugar. No sugar, no trichomes.

As the sugars get broken down, they are then divided and directed to the parts they’re needed. Added magnesium increases the plant’s aroma and the development of sparkling trichomes.


  • Magnesium helps get calcium to where it needs to be
  • Calcium maintains cell structure
  • The stronger the structure, the better the plant
  • Without enough magnesium, you won’t have enough energy for photosynthesis

Honourable Mentions

Manganese is another important micronutrient you will want to have for the regenerative cycle of the plant. This is a vital compound to help aid in building chlorophyll and the process of photosynthesis.

Both processes get ramped up during the regenerative cycle, helping produce flowers, trichomes, and cannabinoids. On top of that, it also helps with enzymatic interactions. Basically, acting as a mediator between different enzymes, helping prevent nutrient lockouts or toxifications.

Molybdenum is one that is rarely, if ever, talked about in the list of nutrients. You can tie this to the use of another nutrient, nitrogen. With a healthy amount of molybdenum, your plant will have a much easier time processing nitrogen throughout the plant.

Not having any of this particular element means your plant cannot process any nitrogen, which will lead to stunted growth rather quickly. With this, you will start to see leaves turning pale in colour and will start to droop and will start to develop red tips before starting to die off. If you ever end up with this deficiency, you will need to correct it fast by testing the PH of your media.

This will usually indicate that your PH level has fallen below 5.5. If that is not the cause, then you will need a Molybdenum fertilizer added to a feed or two to fix it.


These nutrients aren’t just focused on during the flowering process but throughout the whole process of growing the plants. It’s just a matter of how much you need to focus on them that is the trick.

So, don’t be afraid to experiment with adding a little extra of one nutrient during the regenerative stage. You never know what it could improve when given that slight push in the right direction.

Cultivation information, and media is given for those of our clients who live in countries where cannabis cultivation is decriminalised or legal, or to those that operate within a licensed model. We encourage all readers to be aware of their local laws and to ensure they do not break them.

Chris Staniszewski