The cannabis plant is quite resilient. It doesn’t take much to grow it. Give it ample light and water and a decent substrate and it will grow. But when you are cultivating cannabis, you don’t want your crops to just grow. You want them to thrive and give you an abundant yield.

That’s where cannabis nutrition comes in. The right nutrients in the right quantities ensure that your cannabis plants thrive and maximize their bud production. Additionally, essential nutrients give your cannabis plants ample protection against pests and diseases.

But one of the challenges of cultivating cannabis is nutrient deficiency. Whether you are new to the hobby of cultivating marijuana or you’re a seasoned veteran, nutrient deficiency is an issue that you need to address once you detect it in your grow room.

What Is Nutrition Deficiency in Cannabis?

Nutrient deficiency occurs when your cannabis plants do not get enough quantities of the nutrients they require for their growth. The lack of these nutrients can cause stunted growth, lower yields, and vulnerability to a host of pests and diseases.

What Causes Cannabis Nutrient Deficiencies?

It is possible that nutrient deficiency in cannabis is caused by inadequate feeding of nutrients. This is particularly true if you don’t have a thorough understanding of the nutritional needs of cannabis plants during the different growth stages.

However, the most common cause of nutrient deficiency in marijuana plants occurs due to imbalances in the pH level of the substrate. That simply means that even if you give your crops the right amount of the right nutrients, they might not access these.

Cannabis plants absorb nutrients from a substrate through their roots. Now, if the substrate is too alkaline or too acidic, your plants won’t be able to absorb nutrients, even if these are readily available in the substrate.

The optimal pH level for marijuana

The term pH refers to a scale that measures the acidity and alkalinity in the soil. For example, a pH level of one means that the substrate is acidic. On the other hand, if the pH level of the substrate, it means that it is neutral or neither too acidic nor too alkaline.

Cannabis plants thrive when the pH level is between 5.8 and 6.3 or when the growing medium is slightly acidic. At this pH level, the nutrients are dissolved completely and are accessible to your crops. Now, if the pH levels go up or down, even slightly, cannabis plants cannot absorb the nutrients from the substrate. This, in turn, creates nutrient deficiencies.

It is vital to understand that pH levels fluctuate. Adding fertilizers can increase or decrease pH levels. And as a marijuana cultivator, it is up to you to keep the pH level in your chosen substrate stable.

Fixing the pH level of a substrate

Due to the direct link between the pH level of a substrate to cannabis nutrient deficiencies, it is critical to learn how to adjust the pH level. If you are using soil as a substrate, you can adjust its pH level before planting by using powdered sulfur.

But before you do that, it is a good idea to get your soil tested and consult your local nursery to determine the right amount of powdered sulfur to use.

It’s also worth mentioning that it can take months before the right pH level is achieved if you are adding powdered sulfur to the soil.

Now, if you have already planted your cannabis plants and you discovered a pH imbalance, the best thing that you can do is to modify the pH level through the water you use. If you are using an alternative substrate like coir, peat moss, or bark, you should strongly consider adding planting mixes specially formulated to raise or lower pH levels.

Nutrient lockout

Nutrient lockout is another potential reason why your cannabis plants cannot absorb some of the nutrients they need.

This problem arises when nutrients that contain too much salt oversaturate the substrate. A nutrient lockout can also occur if the pH level of the substrate is not ideal. A nutrient lockout can also happen if you overfeed your crops.

To fix a nutrient lockout issue, the first thing that you need is to check if you are providing your crops with the right nutrition in the right amounts. This is particularly true if you are feeding your cannabis plants with nutrients that contain huge amounts of salt.

If you are sure that you are feeding your plants correctly, the next thing that you need to check is the pH level of the soil. To do this, you will need to flush out the substrate. After that, you need to lower the humidity in the grow room to about 49%. Lowering the humidity will help prevent root damage. After flushing the substrate, you’ll need to observe your plants for one full light cycle.

Overwatering and nutrient deficiency in cannabis

How much water you provide can affect the nutrient uptake of a cannabis plant. If you do not give your plant enough water, it won’t be able to absorb the nutrients from the substrate. And on the other end of the spectrum, an overwatered cannabis plant can succumb to nutrient deficiency because the nutrients in the substrate have been watered down.

Understanding the Basics of Cannabis Nutrition

Before learning how to identify and remedy cannabis nutrient deficiencies, it is worthwhile to understand the basics of cannabis nutrition, including which nutrients a cannabis plant needs to thrive at each growth stage. Understanding these basics is one major step that will help prevent cannabis plant deficiencies.

Compared to other commonly planted crops, the cannabis plant needs more nutrients.

If you are planting marijuana outdoors, it is a standard practice among cultivators to add nutrients directly to the soil before transplanting cannabis seedlings. This makes the nutrients readily available all year round for cannabis plants. But aside from adding nutrients to the soil, most growers add top dressing.

On the other hand, if you are an indoor grower, you are more likely to use liquid nutrients which are mixed with water.

Top nutrients for the cannabis plant

Cannabis plants require a diverse array of nutrients for optimal growth, health, and yield.

Among the most important nutrients that your crops need are nitrogen, phosphorus, and potassium. These three nutrients are called macronutrients. Aside from these macronutrients, your cannabis plants also need calcium, magnesium, and sulfur. You will also need to provide your plants with boron, zinc, molybdenum, copper, iron, chlorine, and manganese but in minute quantities.

Take note that as your crops grow, the ratio of these nutrients will change. For example, your plants require more nitrogen during the vegetative stage. During the flowering stage, marijuana plants need more potassium and phosphorus.

But why does a cannabis plant need all these nutrients?

Here is a brief breakdown of the function of these macro and micronutrients.

Nitrogen

Nitrogen is a macronutrient that is crucial for a variety of functions in a cannabis plant, especially during the vegetative stage.

For one, it performs a vital role in producing chlorophyll. When a plant is suffering from nitrogen deficiency, it will have a difficult time converting sunlight into energy. And when that happens, the plant will have a difficult time growing.

Aside from helping produce chlorophyll, nitrogen is also a component of amino acids necessary for the production of proteins. Proteins perform a variety of functions, including strengthening the plant.

Finally, nitrogen aids in the creation of nucleic acid which is a component of plant DNA and RNA.

Phosphorus

Phosphorus is a critical macronutrient during the flowering stage. The primary function of this macronutrient is to allow a cannabis plant to take in other nutrients from the substrate.

Phosphorus deficiency can lead to the underdevelopment of roots. Aside from that, when cannabis plants do not get enough phosphorus will have difficulty producing flowers.

Potassium

Like nitrogen, potassium plays different roles in cannabis plants.

For one, potassium is necessary for osmoregulation or the regulation of salt and water in marijuana plants. Specifically, the macronutrient helps in opening and closing the pores found in the leaves which are known as stomata.

Potassium also plays a role in the production of ATP and glucose. Plants use glucose for energy and growth. When there is potassium deficiency in your crops, they can starve and become weakened.

Calcium

Calcium is necessary for the development and strength of cell walls. A calcium deficiency prevents optimal plant growth.

Magnesium

Magnesium is another nutrient that is necessary for photosynthesis. Specifically, cannabis plants require this nutrient for glucose production. Without it, cannabis cannot convert sunlight into energy.

Aside from aiding in the production of glucose, magnesium is also necessary for the metabolizing of glucose.

Sulfur

Cannabis plants need trace amounts of sulfur. This nutrient helps in the production of plant proteins and enzymes.

Iron

Iron is another nutrient that plays a key role in chlorophyll production. Aside from that, it also helps in producing energy.

Manganese

Manganese performs a variety of roles in a cannabis plant, ranging from photosynthesis to root development.

Boron

Boron is necessary for strengthening plant cells and cell division. It can also be used during cannabis pollination.

Molybdenum

Molybdenum is essential for the conversion of nitrate into nitrite and the conversion of nitrite into ammonia. Ammonia is necessary for the production of amino acids.

Zinc

Zinc is an important ingredient of proteins and plant hormones. Apart from that, it also helps stabilize a plant’s RNA and DNA.

How to Spot and Treat Nutrient Deficiencies in Cannabis

Nutrient deficiency in cannabis doesn’t mean the end of the world. With prompt action, your cannabis plants can bounce back. However, timing and proper action are essential.

Mobile vs. immobile nutrients

Nutrients can either be mobile or immobile. Once your plants absorb and assimilate nutrients, they can move mobile nutrients to different plant parts. Immobile nutrients, on the other hand, cannot be moved.

But what do these mean?

For example, a mobile nutrient is stored in the old leaves. In such a case, the plant can move the nutrient to other parts to remedy the specific nutrition deficiency. Immobile nutrients, on the other hand, stay near where they were initially deposited by a plant.

When there are mobile nutrient deficiencies, you will commonly see symptoms in the older leaves. On the other hand, if there is an immobile nutrient deficiency, the symptoms will appear in new growth, usually among the top branches.

Knowing and understanding the differences between mobile and immobile nutrients can help you spot a nutrient deficiency more quicker.

Understanding nutrient uptake

Nutrient uptake is the process where plants send nutrients to their various parts after absorbing them. Nutrient uptake in cannabis plants is influenced by a few factors.

As previously mentioned, pH level affects a cannabis plant’s ability to take in nutrients from the substrate.

But aside from the pH level of the soil, the pH level of the water you give to your crops can also affect nutrient uptake. As much as possible, you should give your plants water with a pH level of 7. Otherwise, your plants will have a difficult time absorbing much-needed nutrients.

It is also critical to provide your plants with enough water. If you over or under water your plants, they won’t be able to absorb nutrients.

You should also be aware that some nutrients cancel each other out. As such, you should know which nutrient combination works best.

Nitrogen deficiency

Nitrogen deficiency shows itself among the older leaves, especially those that are located near the roots and the middle portion of the affected cannabis plant.

One of the telltale signs of a nitrogen deficiency is yellowing leaves. If you fail to act fast, the affected leaves will eventually die. An affected plant will have leaves that look green and healthy at the top. But below these leaves, you will notice yellowing. The yellowing of the leaves will eventually spread to the topmost leaves.

Nitrogen deficiency usually appears during the flowering stage when flowering cannabis uses the nutrients stored in the leaves. Although the yellow leaves have no chance of recovering and eventually falling off, you can fix this nutrient deficiency.

You can add a variety of products, including bat manure, fish meal, worm castings, and blood meal to increase nitrogen levels in the substrate. When amending the soil, be sure to check the pH level of the soil.

Phosphorus deficiency

A plant that has a phosphorus deficiency will lack vigor and have dark leaves. It is also common for plants with this nutrient deficiency to have stunted growth. A close look at a plant with phosphorus deficiency will show brown and curling leaves.

Typically, cannabis plants succumb to phosphorus deficiencies during winter when plants need to work doubly hard to absorb nutrients from the substrate.

To fix a phosphorus deficiency, you can use fertilizers with a higher ratio of nutrient or all-purpose plant food. Bat manure, bone meal, and worm castings can also help solve this nutrient deficiency.

Potassium deficiency

Potassium deficiency is one of the most common cannabis nutrition deficiencies. This problem arises because most fertilizer formulations have lower levels of this nutrient.

It can be pretty hard to spot potassium deficiency in marijuana plants because the affected crops seem to be healthy, albeit taller than plants that are unaffected.

One sign that a plant has this type of nutrient deficiency is the browning of the leaves, especially around the leaf tips and edges. Additionally, potassium-deprived plants tend to be more fragile and susceptible to bending and breaking. Other signs of potassium deficiency include mottled and yellowing of the leaves.

To remedy this problem, you will need to add more potassium to the substrate. Most affected plants respond quickly, even if the pH level of the substrate is not exactly spot on. Kelp meal, wood ash, granite dust, and sulfate of potash are among the alternatives you can choose from if you wish to pursue the organic route.

Magnesium deficiency

Among the different nutrient deficiencies in cannabis, magnesium deficiency is quite uncommon. If it does occur, it usually happens in hydroponic setups.

Plants affected by this nutrient deficiency have yellow leaves near the base. Eventually, the yellowing of the leaves moves upward. The new shoots will take a white to pale green color. The stems and petioles, on the other hand, have a purple hue. As the magnesium deficiency progresses, brown spots begin to appear. Some growers report seeing the stems change their color to red.

Epsom salts are the most common remedy used to fix a magnesium deficiency. You may also want to try worm castings, dolomite lime, garden lime, and magnesium sulfate.

Calcium deficiency

If you are cultivating indoors with a hydroponic system, one nutrient deficiency that you should watch out for is calcium deficiency. A calcium deficiency usually occurs because there isn’t enough calcium in the water.

One sign that your plants have succumbed to a calcium deficiency is dead patches on the leaves. Typically, you will see this sign on the older leaves. Additionally, plants affected by a calcium deficiency have weak branches such that they cannot support the weight. Left unchecked, a calcium deficiency can also affect the roots.

To fix a calcium deficiency, you can use lime and apply it to your substrate.

Iron deficiency

Iron deficiency is quite rare in cannabis plants. This nutrient deficiency typically shows in new growth, causing yellowing of the leaves. But despite the yellowing leaves, you will notice that the leaf veins still have a green color.

To the untrained eye, an iron deficiency looks like a magnesium deficiency. To distinguish between the two nutrient deficiencies, you have to check which plant parts have been affected.

In an iron deficiency, the top leaves are the most affected parts. Iron deficiency usually occurs alongside other nutrient deficiencies and the wrong pH levels.

Sulfur deficiency

Among the different nutrient deficiencies, sulfur deficiency is among the rarest. This is because most fertilizer formulations have sufficient amounts of this nutrient.

A sulfur deficiency typically shows itself in the form of the yellowing of new leaves. Additionally, a plant lacking in this nutrient will have stunted growth.

Epsom salts and potassium sulfate are the best remedies for sulfur deficiency.

Zinc deficiency

Cannabis plants do not require too much zinc. However, zinc deficiency is common to the hobby. A plant with a zinc deficiency will display yellowing of the leaf veins in older leaves and twisting in new growths. In some cases, a plant that has succumbed to zinc deficiency will lose its color, giving it a pale appearance.

If the zinc deficiency happens during the flowering stage, the buds may also look pale and deformed. Usually, zinc deficiencies occur alongside other nutrient deficiencies.

To fix this issue, you can use a micro mix containing iron, zinc, and manganese. Alternatively, some cultivators use chelated zinc, zinc oxide, or zinc sulfate.

What to Do After Detecting Nutrient Deficiencies

Cannabis nutrient deficiencies can and do happen, whether you are a newbie or a seasoned marijuana cultivator. If your crops succumb to any of the aforementioned cannabis nutrient deficiencies, do not be disheartened. With prompt action, you can turn things around.

As soon as you notice signs of a deficiency, one of the first things that you need to do is to check the fertilizer you provide your plants. It is also a good idea to determine whether the nutrient rations are appropriate for your crops and if you have followed closely the manufacturer’s feeding recommendation. Next, check the pH level of your substrate. Ideally, the pH level of the substrate should not go below 5.6.

Preventing Nutrient Deficiencies in Cannabis

Although getting cannabis plant nutrition is no rocket science, there are plenty of things to consider. Miss one or a couple of things and you might be facing cannabis plant deficiencies in the near future.

To prevent this issue, consider following these tips.

Test your substrate’s pH level

The pH level of your substrate is one of the key factors that influence nutrient uptake. As such, it is a good ideal to keep the pH level of your chosen substrate within the appropriate level.

If you are using soil, the optimal range is between 5.8 and 6.8. On the other hand, if you are using a hydroponic system, the best pH range would be between 5.5 and 6.5.

Feed your plants right

On one end of the spectrum, you should provide your plants with quality fertilizers. And as much as possible, limit or watch closely your use of salt-based fertilizers. Too much salt draws out moisture from the substrate, making it harder for the plant roots to derive nutrients. If you are using a new fertilizer, be sure to read carefully the instructions and recommendations.

Less is more

It is quite tempting to give your plants more fertilizers than they actually need. But as with most things, too much of a good thing can be bad. Never give your crops more nutrients than they need.

You can end up wasting your hard-earned money. Worse, you can kill your plants instead of making them healthier and more productive. Use the feed chart to help you learn which nutrients you should provide your plants at which times.

Flush your plants

Over time, nutrients accumulate in the substrate. When this happens, problems like nutrient deficiencies and nutrient lockout can occur. One way to prevent any of these from happening is to flush your plants.

Allowing a considerable amount of water to pass through the substrate removes excess nutrients and enables the plants to use up all their nutrient stores. Typically, flushing is done two weeks before harvest or while your crops are still in the vegetative stage. Flushing can also be done if you are facing a nutrient deficiency issue.

Monitor your crops daily

Catching nutrient deficiencies in cannabis early on can prevent things from spiralling out of control. As much as possible, make it a habit to monitor the condition of your plants, especially their leaves.

Bouncing Back from Nutrient Deficiencies

Nutrient deficiencies does not mean that all your efforts have been wasted. If you act fast and undertake the necessary steps to remedy the cannabis nutrient deficiencies you are currently facing, your marijuana plants can bounce back and recover.