Nutrient Deficiencies in Cannabis: A Complete Guide

Vegetables are great for you, but try eating only tomatoes and potatoes for a month, and you’ll probably earn a visit to the doctor. That’s because your body requires a lot of different kinds of nutrients, which are not present in tomatoes and potatoes. This is why a healthy diet consists of vegetables, sprouts, meat, eggs, and, sometimes, even cheese and wine! 

Similarly, your cannabis plant also needs a variety of nutrients to thrive, and even if a single one of these nutrients is absent from the soil, your cannabis plant can suffer from a deficiency that can lead to various issues for the cannabis plant. 

Learn the basics of the most common nutrient deficiencies in this article, along with some tips and tricks on treating and preventing them. 

What Nutrients are Important for Cannabis? 

On the face of it, nutrient deficiency may not look like much — you won’t die if you never touch green veggies, right? — but that’s not the case with cannabis. Their diet is already pretty restricted, and if they lack necessary nutrients, they may suffer problems such as:

• Stunted growth 
• Loss of vigor 
• Smaller plant size 
• Smaller yield 
• Low potency buds 
• Buds that lack aroma and flavors, etc.

Fortunately, cannabis is quite a communicative plant, and it won’t hesitate to tell you what it needs. A cannabis plant suffering from nutrient deficiencies often shows various symptoms along the lines of wilting, curled leaves, yellowing leaves, discoloration, etc. 

But, let’s hold our horses for now and learn what these nutrients are and how they benefit your cannabis plant. You need to know what you are dealing with, right? 

Types of Nutrients 

Cannabis requires two types of nutrients: macronutrients and micronutrients. The former include nitrogen, potassium, and phosphorus (NPK nutrients), which are required by cannabis in the highest quantity. Your cannabis plant won’t survive without these nutrients at all. 

On the other hand are micronutrients, which are just as crucial for your plant’s health but cannabis only requires these nutrients in smaller quantities. These nutrients include zinc, iron, calcium, magnesium, sulfur, boron, etc. Don’t ever underestimate micronutrients; your plant won’t survive without these either. 

Mobility of Nutrients 

Nutrients can also be grouped according to their ability to be mobile within the plant. This further helps identify and fix nutrient deficiencies in cannabis plants. So, what exactly is the mobility of nutrients? 

Any nutrients that are transported from one part of the plant to another based on the plant’s needs are referred to as mobile nutrients. One of the best examples of this is phosphorus, which is usually stored in older fa leaves but can be transported to newer leaves if required. Thus, mobile nutrient deficiencies are commonly seen in the older leaves first. 

Here are the common mobile nutrients required for your cannabis plant:

• Nitrogen
• Phosphorus
• Potassium 
• Magnesium 
• Sulfur (limited mobility)

On the contrary, immobile nutrients refer to those that are not transported within the plant; they stay put in place, regardless of any deficiencies occurring in any other part of the plant. This is why immobile nutrient deficiencies are first visible on new leaves since the older leaves have some reserves left. 

Here are the common immobile nutrients required by cannabis:

• Calcium 
• Iron 
• Manganese
• Boron
• Molybdenum 
• Zinc 

Now that you have an understanding of the types of nutrients and where deficiencies can occur let's delve into the topic.

Common Nutrient Deficiencies in Cannabis 

Your plants can experience various kinds of nutrient deficiencies — some of which are rare while others are more common. 

Here are the nutrient deficiencies your cannabis plant may face sometimes and how to treat them. 

1. Nitrogen Deficiency 

Nitrogen is one of the most essential nutrients required by your cannabis plant, and this macronutrient is essential for various processes like photosynthesis and protein formation within the plant. 

If your cannabis plant is suffering from a nitrogen deficiency, the most common symptoms include yellowing, withering, or discoloration of older leaves, which slowly progress to newer growth and eventually cover the entire plant. Eventually, nitrogen deficiency can lead to subpar yields and poor growth of the plant. 

One crucial nutrient for your cannabis plant is nitrogen. It plays a role in processes such as photosynthesis and protein formation within the plant. When cannabis plants experience a lack of nitrogen it can result in symptoms that negatively impact their health and productivity. 

Nitrogen plays a key role, in the growth and development of cannabis plants. As one among the three main macronutrients, it contributes to plant health by forming proteins, amino acids, and even chlorophyll formation which are essential for photosynthesis. As you already know, nitrogen deficiency causes various problems, so you should understand the causes and how to prevent it to grow healthy plants. 

One noticeable symptom of nitrogen deficiency is that the leaves start to turn yellow, typically beginning at the lower leaves. Remember we discussed mobility? The older leaves transport nitrogen to the younger leaves, so the older leaves turn yellow first. Gradually, it will spread to the younger leaves if you don’t address the situation quickly. 

But, that’s not all. Yellowing leaves can be fixed, but another problem that poses a significant disadvantage is stunted growth. Insufficient nitrogen availability can prevent the leaves, branches, and stems from growing as they should because nitorgen plays a crucial role in protein synthesis and the formation of amino acids. 

With photoperiod plants, you can still fix stunted growth and make up for lost time if you act quickly. However, with autoflowers, you will lose precious time. Since autoflowers don’t depend on light to flower and will do so when they grow to a specific age, time is significant. If you’re growing autoflowers, make sure you address the problem immediately if you don’t want to lose yields. 

Coming to what causes nitrogen deficiency, the first and most obvious cause is that you could be feeding nutrients that don’t contain much nitrogen. This is very common in soilless or hydroponic systems. 

Another reason is that there could be an imbalance in the pH. The availability of nitrogen is linked very closely to pH levels. Thus, if you’re using growing mediums with a pH less than 5.5, it can reduce the availability of nitrogen for absorption by plant roots. 

Next, you might be overwatering the plants. If the plant is watered beyond what’s necessary, such wet conditions can limit the oxygen available and the roots will suffer as they can’t absorb nitrogen. Also, if the roots are damaged due to some reason, whether it’s pests or stress, the plant will again show symptoms of nitrogen deficiency. 

Finally, your plant can experience a lack of nitrogen and show various symptoms if you don’t use a balanced nutrient feed. For instance, if your fertilizer or nutrient solution contains excessive amounts of magnesium or calcium, they will compete for the uptake of nitrogen with the roots and the plant will then show signs of distress. 

The good news is that you can easily address and correct nitrogen deficiencies in cannabis plants. First, you need to assess your nutrient solution. Make sure it contains nitrogen and then feed it to your plants. Read the label carefully and you’ll know the composition. Next, feed the solution throughout the plant’s vegetative cycle. This doesn’t mean that you should stop providing nitrogen during the flowering phase; however, the amounts will be smaller. Therefore, read the manufacturer's instructions carefully to make your nutrient solution. 

Next, monitor your pH levels and adjust as necessary. Whatever the case, make sure the levels do not go above or below the desired pH range, followed by applying compost tea foliar spray to give your plant a nitrogen boost. You can even try to incorporate some organic fertilizers that are rich in nitrogen like manure, fish meal, or alfalfa. This should ideally fix nitrogen deficiency in cannabis plants. 

Monitor and regulate the pH levels of your growing medium to ensure that it falls within the range for nitrogen absorption. For soil-based cultivation, aim for a pH of around 6.0 to 7.0 while hydroponic or soilless systems should have a pH of 5.5 to 6.5.

You should also stick to a proper watering schedule rather than watering whenever you feel like it. Avoid overwatering at any cost and feed the plants only when required to encourage oxygen availability for roots.

Ideally, it is also recommended to use compost and mycorrhizae; the latter is an excellent nitrogen-fixer for the roots and can boost the nitrogen levels in the growing medium significantly. 

2. Phosphorus Deficiency 

Phosphorus is another macronutrient cannabis plants need to grow well. It plays a huge role in biological processes like energy transfer, DNA and RNA formation, and photosynthesis. Naturally, when cannabis plants lack this important nutrient, they will show several signs. Ultimately, phosphorus deficiency can prevent the plant from growing properly and reduce yields. 

Like nitrogen, this macronutrient is mobile and is often directed to the part that requires it the most. If your cannabis plant is suffering from a phosphorus deficiency, it will usually show symptoms like brown spots on the leaves, leaves drying out, and the formation of red or purple spots on the stem, especially in older growth. This purple color occurs due to increased levels of anthocyanins, which are nothing but pigments that are more noticeable when there is a shortage of phosphorus.

Plants deficient in phosphorus will also flower much later than expected as this nutrient is crucial for the plant during the flowering stage. The buds will also not form fully and you’ll be left with small buds that look like they suddenly decided to stop growing. The same applies to the leaves as well. Not only will they look slightly stunted and small, but they may also appear twisted at times. Since this nutrient is important during the flowering stage, the nutrients you should use during the blooming stage (Part B, usually) will typically have higher amounts of phosphorus. 

One interesting part of phosphorus deficiency is that although the stems may appear reddish or purple, the leaves will look extra green and shiny, as the plant will divert the phosphorus from its older leaves to the younger ones which leads to the stems looking discolored. 

Various factors could cause phosphorus deficiency in cannabis plants, but, again, the most obvious one is that you may be using a nutrient solution containing very less phosphorus. And, the other reason? You guessed it — pH imbalance indeed. Like nitrogen, the plant will struggle to absorb phosphorus if the pH dips below 6 when you’re growing in soil. 

So, how do you fix phosphorus deficiency? It’s relatively easy. As always, you want to check and adjust the pH and set it slightly higher to promote phosphorus absorption by the roots. Additionally, you should use worm casting or fish meal as these supplements are rich in phosphorus. 

Also, check your watering routine and make sure you are not overwatering your cannabis plant. You only need to water the plant when the top inch of the soil is dry and water it until 25% of the water runs off from the drain holes. You can also try moving your cannabis to a warmer part of the grow room as cannabis finds it difficult to absorb this nutrient if the temperature drops below 60°F or 16°C. 

As for preventing phosphorus deficiency from occurring in your cannabis plant, you should use organic soil that is well-aerated, and even mycorrhizal fungi can help here by fixing phosphorus for the roots. And if you’re using compost, consider adding more manure to it as it is rich in phosphorus. 

3. Potassium Deficiency 

Potassium is the last of the crucial macronutrients required by your cannabis plant, and this mobile nutrient has various roles to play in your plant’s health. For example, potassium regulates carbon dioxide intake, aids photosynthesis, and helps in ATP production. 

A cannabis plant suffering from a potassium deficiency presents itself with symptoms like yellowing or browning leaf tips and edges, unexpected plant stretching, and curled leaves. 

The best way to fix potassium deficiency in cannabis plants is by flushing the growing medium, checking and adjusting the pH to cure potential potassium lockout, using organic seaweed foliar spray, and adding chicken manure to the growing medium. 

As for preventing potassium deficiency in cannabis, you need to use the right fertilizers that don’t cause salt buildup in the soil, which can hamper potassium uptake, along with adding hardwood ash or kelp meal to the compost. Also, avoid overwatering as it can wash away potassium from the growing medium before the plant has any chance to absorb it. 

4. Calcium and Magnesium

Calcium and magnesium play drastically different roles in cannabis plants, but they somewhat go hand in hand. For instance, excess calcium can hamper magnesium uptake and vice versa, potentially leading to calcium or magnesium deficiencies. 

Calcium is a micronutrient that’s required in the plant’s cell walls, and if your plant doesn’t get enough of it, you’ll notice symptoms like warped or incorrect formation of new growth. Speaking of magnesium, this micronutrient is mobile and without it, your plant cannot conduct photosynthesis. This nutrient is one of the core compounds of chlorophyll, without which it fails to absorb light. Common symptoms of magnesium deficiency include yellowing, browning, or drying of leaves. 

So, how do you fix calcium and/or magnesium deficiency? Start by adjusting the pH of the soil followed by adding cal-mag solution to it, especially if your plant is facing calcium deficiency. You can also try adding 1 tbsp of hydrated lime (for calcium) and 1 tsp of Epsom salt (for magnesium) to a gallon of water to irrigate your plant. 

As for preventing calcium and/or magnesium deficiency, you should add dolomitic lime to the growing medium, use compost in the soil, and add other supplements like egg shells or worm castings. 

5. Iron Deficiency 

Now we’re heading to micronutrients that are not required as much as calcium and magnesium, and the first micronutrient up this list is iron, which is an essential part of chlorophyll. This mineral also aids enzyme formation and pigmentation. Essentially, iron is an immobile nutrient that aids various energy-forming and metabolic functions of the plant.

When your cannabis plant suffers from iron deficiency, the common symptoms you’ll see are the leaves turning bright yellow on the top. To fix this problem, you need to adjust the pH of the growing medium, flush it, and supplement it with iron supplements. You can even try keeping the pH on the lower end of the spectrum to improve iron accessibility; a pinch of nitrogen fertilizer should do the trick. 

6. Copper Deficiency 

Copper is a micronutrient catalyst for your cannabis plant as it aids in protein and enzyme synthesis along with lignin formation that gives your cannabis plant structural integrity. If your cannabis plant doesn’t get enough copper, it will start developing symptoms like stunted growth, chlorosis, curled leaves, necrotic spots, etc. 

The best way to treat copper deficiency is by adding more copper into the nutrient solution via a copper-rich supplement while maintaining the pH on the slightly higher end of the spectrum. 

7. Zinc Deficiency 

Cannabis plants don’t use a lot of zinc, but when they do, it is for very important processes. Essentially, zinc is required by cannabis for protein synthesis and production of growth hormones. Plus, zinc is responsible for enzyme regulation and DNA/RNA stabilization. 

In case of a zinc deficiency, your cannabis plant will exhibit symptoms in the newer growth first. The most common symptoms include stunted growth, nodes getting closer together, and leaves turning yellow or wrinkly. The leaves may also develop rusty tips if this is not addressed on time.

The first step you need to take to fix zinc deficiency is to reduce the pH of the soil and check your watering schedule to ensure you are not overwatering your plant. For a zinc boost, you can use seaweed foliar spray. 

To prevent zinc deficiency, ensure the pH of the soil is slightly on the acidic side, use pumpkin in compost, and add beneficial bacteria to the soil. 

8. Manganese Deficiency

Manganese is an underrated nutrient for the cannabis plant, and while it may not get the attention it deserves, this immobile nutrient is still crucial for your cannabis plant. This nutrient comes in handy for respiration, nitrogen absorption, photosynthesis, root cell development, and microbe resistance. 

So, if your cannabis plant is suffering from manganese deficiency, it will develop symptoms like light green discoloration of the leaves, especially on the newer leaves, which will eventually cover the entire leaf and turn it brown. 

To fix manganese deficiency in your cannabis plant, try adding manganese-rich compost to the soil; ideally, you should add tomatoes, pineapple, and carrots to the compost pile to make it manganese-rich. You should also flush the growing medium and prune away any infected parts that don’t recover. As a quick fix, seaweed as foliar spray also comes in handy. 

9. Boron Deficiency

Boron is another micronutrient that’s not required in large amounts, but it plays a crucial role in your plant’s structural integrity. This mineral complements calcium to build cell walls and aid cell division. Plus, it plays a crucial role in pollination.

The symptoms to look out for if you suspect boron deficiency include turgor loss, poor growth, lost meristems, infertility, twisted sugar leaves, and yellow/brown discoloration. To fix this problem, you need to flush the growing medium, check the pH, and use a boric acid/water solution to irrigate the plant. For the solution, you need to add a teaspoon of boric acid to a gallon of water. 

The best way of preventing boron deficiency is by watering the plant on time, not overfeeding it, and keeping the humidity above 25%. Also, you can add bananas, apples, or broccoli to the compost pile to give it a boron boost. 

10. Sulfur Deficiency

Your cannabis plant does not require sulfur in large quantities, but what little it does require can play a major role in your plant’s health. Sulfur is an immobile nutrient that is an essential building block of various proteins and enzymes, and a lack of it can cause symptoms like discolored undersides of the leaves or yellowing of younger leaves. 

The best way to fix sulfur deficiency is by giving your cannabis plant a boost with Epsom salt — 2 teaspoons of it in a gallon of water should do the trick. You can also try adjusting the pH. 

To prevent sulfur deficiency from occurring in your cannabis plant, you should use a manure-rich compost pile, add mycorrhizae to the soil, and use the no-till method. 

11. Molybdenum Deficiency

Molybdenum is yet another micronutrient that’s required in smaller quantities but is significantly underrated. This mineral aids the formation of enzymes that are responsible for converting nitrate into nitrite, which is then converted to ammonia. This ammonia is then used to produce amino acids that lead to protein synthesis. 

So, if your cannabis plant does not get enough molybdenum, all the above-mentioned processes can get affected, leading to symptoms like pink or red discoloration on the edges of young leaves along with occasional yellow spotting. 

Fortunately, molybdenum deficiency is quite rare, but if your plant suffers from it, it’s easy to fix. If you are unlucky enough to face this with your cannabis plant, the best way to treat it is by flushing the growing medium, adjusting the pH, and spraying the plant with seaweed foliar. You can also add some worm-casting-rich compost tea. 

As for preventing it, maintain the right pH value of the growing medium and use high-quality soil with compost. That’s all you need to do to prevent molybdenum deficiency in your cannabis plant. 

Additional Tips on Preventing and Treating Common Nutrient Deficiencies in Cannabis 

You’ve got a top-down on the most common nutrient deficiencies your cannabis plant may face, but there’s always more to learn about this problem. So, here are some more tips and tricks that will allow you to better deal with nutrient deficiencies in your plant. 

1. Always Pay Attention to the pH of the Growing Medium 

As you may have already guessed, maintaining the right pH can help you prevent nutrient deficiencies more often than not. This is because when the pH is right, the roots can absorb the nutrients properly, but the moment the pH is thrown off, the roots fail to absorb some nutrients, leading to a nutrient lockout. 

The best pH range for a cannabis plant is between 6.0 to 7.0 in soil and 5.5 to 6.5 for hydroponic cannabis, but be sure to consider your strain’s requirements, local climate, and growing medium to set the right pH for your plant. And it’s advisable to invest in a good pH pen so you don’t have to tinker with pH strips. 

2. Choose Good Nutrients 

Your cannabis plant’s soil is teeming with life, which plays a crucial role in fixing nutrients for your cannabis plant. These microbes break down the minerals and make them easier to absorb for the plant's roots. So, it’s important to focus on cultivating cannabis in living soil as much as you can. 

By using organic nutrients or fertilizers, you encourage these friendly bacteria and fungi to thrive in the rhizosphere, allowing for more nutrient accessibility for the roots. 

3. Use Foliar Spray for a Quick Boost

By fixing the problem at the root, pun unintended, you are doing the right thing, but the results can take time to show. So, it is recommended that you use the appropriate foliar spray to give your cannabis plant a quick boost if it faces any kind of nutrient deficiency. 

4. Use High-Quality Fertilizers

Regardless of the kind of fertilizers or supplements you use to grow cannabis, you must never compromise on quality. High-quality fertilizers are rich in all the essential nutrients, are much more stable and safe for the plant, and often come with reliable ingredient lists and instructions. The results will always be worth the extra cost you pay for them. 

5. Flush Your Growing Medium Regularly 

Over time, many nutrients can build up in the rhizosphere, leading to nutrient lockouts. Take calcium and magnesium for example; if there’s a calcium buildup in the soil, it can lead to magnesium lockout. So, it is important to flush the growing medium with RO water regularly to wash away any salt buildups. 

6. Learn About Nutrient Interactions 

In the same vein, you must learn how various nutrients interact with each other. This will help you maintain the health of your cannabis plant. Here are some common nutrient interactions that you need to be aware of:

• Calcium and magnesium 
• Zinc and phosphorus
• Magnesium and potassium
• Phosphorus and calcium 
• Manganese and iron 

Excess of one can lead to a deficiency of the other and vice versa, so it is crucial to maintain the right concentrations for these pairings in your soil. 

Summary: Nutrient Deficiencies in Cannabis: A Complete Guide

These were the common nutrient deficiencies your cannabis plant may face, especially if you are a new grower. And while they may seem scary, they are relatively common and easy to fix in most cases. All you need to focus on is the right strategy:

1. Assess the symptoms and figure out which nutrient deficiency your cannabis plant is facing
2. Check your nutrient solution’s concentration 
3. Check the pH of the soil and fix it 
4. Ensure the temperature, RH, light, and other factors are ideal for your plant’s requirements 
5. Flush your growing medium 
6. Give your cannabis plant the right kind of nutrient boost 
7. Factor in any potential interactions between various nutrients 

That’s it. In most cases, following these steps will help you fix nutrient deficiencies in no time. As for other cannabis-related problems that you may encounter in your journey as a grower, stay tuned to our blog to know more.