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Table of Contents

Guide To Cannabis Nutrient Deficiency

Issues with cannabis nutrient deficiency is one of the biggest mysteries in cannabis cultivation. This is especially true for new and beginner cannabis growers. During the cannabis growing cycle there are many nutrients that cannabis needs to grow healthy and quickly. This is even more so in the flowering cycle of the cannabis plants. 

To make matters even more difficult is that the plants need different types and amounts of nutrients in their different stages of growth. On top of this the plants also need MacroNutrients and Micronutrients to grow many top shelf cannabis buds for the growers. 

Cannabis nutrient deficiency is one of the most important skills that any grower will need to learn to grow healthy and productive cannabis plants. Knowing how to diagnose, prevent and fix cannabis deficiencies will be our topic in this guide. It can be complicated as cannabis plants rely on 18 essential nutrients to grow well.

Cannabis Nutrient Deficiencies
Late Stage Magnesium (Mg) Deficiency

What are Cannabis Nutrients?

Cannabis nutrients are much like human nutrients, every plant needs them to grow strong, the same as humans need them to grow and stay healthy. Like humans get their nutrients from foods they eat, plants get these nutrients by taking them in from the roots, or though their leaves. Cannabis needs the right types of nutrients, such as nitrogen, phosphorus and potassium to fight off disease. They keep the plant growing green, and they need them throughout their entire growing cycles. 

Why are Nutrients so Important for Growing Great Cannabis?

As soon as the plant emerges from the seed it will require nutrients to grow, fight diseases and pests and to create seeds for the next growing season. Having the nutrients in amounts needed to support photosynthesis, of the plant as it grows to harvest or to produce seeds for many growing seasons to come. If your plants do not have the nutrients in larger or smaller amounts as needed they will start to show cannabis nutrient deficiency within days. 

This can happen quickly for some growing types, such as hydroponic growing. It can take much longer to see these deficiencies in soil grown cannabis plants. Plant nutrients keep your cannabis lush and green.

What are Macronutrients?

There are three main nutrients that cannabis plants require for healthy growth. These nutrients are referred to as macronutrients and are needed in larger amounts. They include nitrogen, phosphorus and potassium. They will be listed in any fertilizer container as N-P-K and this is the amount that will be available to the plant. These main nutrients are critical for growing cannabis plants successfully. 

Macronutrient Cannabis Deficiencies

What are Micronutrients?

While macronutrients may be considered the most important nutrients, micronutrients are also important for growing top shelf cannabis plants. These are still important nutrients however they are needed in lesser amounts then the big three macronutrients. Still if any of these are in short supply in the growing medium they can cause all sorts of issues when growing your plants. 

These nutrients include, boron (b), manganese (Mn), magnesium (Mg), calcium (Ca), sulfur (So), boron (B), copper (Cu), iron (Fe), and zinc (Zn). There are also a few others not listed here but these ones are some of the most important ones for plant growth.

Mobile vs Immobile Nutrients

Now that we have discussed the types of nutrients that cannabis needs to grow, next we will discuss how the nutrients work once they get into the plants. 

Each type of nutrient above once it is brought into the plant by either the leaves or the roots, can stay put, or be moved within the plant. In simple terms this means that if the plant has an excess of nitrogen in its bottom leaves, the plant can move them elsewhere in the plant as needed. A immobile nutrient, such as copper once it is in the plant, can not be moved as needed to other growth areas in the plant. 

ELEMENT (Symbol)

MOBILITY IN PLANT

NUTRIENT DEFICIENCY FOUND IN

Nitrogen (N)

Mobile

Old leaves

Phosphorous (P)

Mobile

Old leaves

Potassium (K)

Mobile

Old leaves

Calcium (Ca)

Immobile

New leaves

Sulfur (S)

Immobile

New leaves

Magnesium (Mg)

Mobile

Old leaves

Iron (Fe)

Immobile

New leaves

Manganese (Mn)

Immobile

New leaves

Boron (B)

Immobile

New leaves

Molybdenum (Mo)

Immobile

New leaves

Zinc (Zn)

Immobile

New leaves

Why is this so important when it comes to Cannabis Nutrient Deficiency?

Knowing which nutrients the plant can move within can help a grower understand which type of deficiency they are dealing with. Many times if the nutrient issue is in the older plant growth, it will signal to the grower that the plant is deficient for a mobile nutrient. The plant is putting nutrients out of older growth to support newer cannabis growth. 

On the other hand if the plant is showing signs of deficiency in newer plant growth such as the growth nodes of the cannabis plant, this could signal that the plant is lacking nutrients that are immobile.

Guess What? PH can also Factor into Cannabis Nutrient Deficiency

Probably one of the biggest “got yas” for new growers and nutrient issues is how PH can factor into how the cannabis can uptake and process nutrients. Cannabis needs to have a PH range that is correct otherwise the plant will never be able to take in nutrients from its roots. 

If the PH is not in the correct range for the plant it will not matter how much of each nutrient that plant has access to. Cannabis news to have the PH in the right range for the nutrients to be able to move up into the plant. Another factor in this equation is that some nutrients are better absorbed in different parts of the PH range. So one nutrient may be more available to the plant in the lower end of the range; another may not be as easily absorbed there.  If you are interested in learning more detailed information about cannabis plant PH we have an excellent article you may read here.

Cannabis PH Issues
Cannabis PH Issues

How Growing Organic Helps Minimize Cannabis Nutrient Deficiency?

One of our favorite ways to grow is using organic nutrients. The goal of growing organic is to give the plant just enough nutrients to maintain healthy growth in all cycles. Organic nutrients added to the soil break down slowly so the plant will have access to them as needed. Bacteria and Fungi in the soil help to break them down providing a good steady supply of nutrients for the plants. We have a couple great articles that we recommend reading if you are interested in organic fertilizer and organic cannabis cultivation.

How Nutrient Demand Changes through Growth Cycles?

When cannabis grows though its yearly cycles in nature it needs more or less of certain nutrients as the plant grows and matures. When the seed first germinates it will only need a very small amount of nutrients to give the plant support until it grows its first true set of cannabis leaves. 

As the plant grows through its vegetative stage of growth it will require more amounts of nitrogen(N), magnesium (Mg), calcium (Ca) to grow large green leaves. Once the plant starts its flowering stage of growth, it will start to need far less nitrogen, but still need magnesium and calcium, at this point the plant will need more phosphorus and potassium to grow healthy, large cannabis buds. If you are interested in reading more about growing large cannabis buds we recommend this article. If too little or too much of these nutrients are present they can slow grow and the plant may not be as healthy.

Cannabis Nutrient Deficiency by Nutrient

We will break down each nutrient, what it does in the plant and what to look for if you are deficient in the nutrient.

Nitrogen

Nitrogen is one of the main components for the plant to make chlorophyll, (what makes the plant green and healthy). This deficiency will so up first in older leaves as it is a mobile nutrient. The plant will take nitrogen from its older leaves to move to new growth. The lower leaves will first show signs of deficiency as the leaves on the bottom of the plant will start to turn yellow. 

This nutrient plays a big part in processing amino acids and proteins in your cannabis plants.

Nitrogen Cannabis Deficiency
Nitrogen Cannabis Deficiency

Phosphorus

Another essential nutrient for healthy plant growth and especially during the flowering period for cannabis plants. It is directly involved in cell membrane and function within the plant. Some of the symptoms of phosphorus deficiency can include, purple or reddish discolorations of plant leaves and stem. The grower may also have issues with slow plant growth, and poor root development. 

If this nutrient is deficient in flowering, the grower will notice poor bud formation. It will impact bud harvest with lower yields. This cannabis nutrient deficiency will first appear in older growth.

Phosphorus Cannabis Deficiency
Phosphorus Cannabis Deficiency

Potassium

A very important nutrient when it comes to plant metabolism. This nutrient helps with regulation of plant water loss, and controlling plant stress. These stresses can include cold, heat and lack of water. Symptoms of deficiency of this nutrient include yellowing of the plant margins, veins and can also include in later stages leaf crinkle and leaves may start to roll up.

Two Very Important Micronutrients

These two nutrients work together and are very important for growing great cannabis. They are magnesium (Mg), calcium (Ca) and they work together in the plant to keep it healthy. Magnesium works to keep leaves healthy with chlorophyll much like nitrogen in the plant. It helps to “glue” the plant cells together and be healthy.  

Magnesium deficiency will look like yellowing of the veins of the plants, The tips of the leaves may also turn brown and as the symptoms get worse over time the leaves will eventually die and fall off. 

Calcium works with magnesium to help enzymatic reactions in your cannabis plants. Another nutrient that also helps to bond cannabis plant cells together. When the plant is deficient in calcium the leaves will start to look dry and brown on the tips. The brown from the tips of the plant will slowly work their way back into the leaves. This will also eventually kill the leaves of the plant.

Magnesium Cannabis Deficiency
Magnesium Cannabis Deficiency

What is Nutrient Leaching?

Sometimes when growers have nutrient issues, it is best to just start all over with your medium. You can do this by leaching your growing mediums. To do this, the grower will need to run plain water from the medium to flush everything that is nutrient in it. It is best to run the water over the medium until there is a very good amount of water running through the pots and out the bottom.

What is Soil nutrient mobility?

Like within cannabis plants, some nutrients can move within your growing medium or soil with greater ease than others. This will factor into the leaching of the medium as some nutrients can be removed from the soil easier than others. This is why it is important to run a good amount of water through to get everything back to a clean baseline. For example it is very easy to leach nitrogen from the soil.

Final Thoughts

For any grower it is important to remember that nutrients work with everything in the plant environment for best results. All the great nutrients, in the correct amounts will mean nothing if your PH is not correct in the growing medium. The same can be said about lighting, C02, cannabis grow lighting, and temperature. Many of these things listed can also contribute to what may look like cannabis nutrient deficiency in your plants. 

Cannabis will only grow the best buds depending on its weakest link. Sometimes that can be nutrient deficiency, other times it could be something else that is affecting the plants. 

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