First off, know that Nutrient Deficiencies in Cannabis Plants happen to the best of growers. No matter the growing technique used or the growing medium chosen. Soil, hydroponics, aeroponics, rock wool and even soilless grown plants are all susceptible to nutrient deficiencies. That being said, indoor grown plants are more likely to develop these issues rather than outdoor grown plants. Unfortunately, nutrient deficiencies slow the growth of the marijuana plant. Therefore, constant checks of the plants nutrient levels is imperative. Especially for newbie growers.

Nutrient Deficiencies in Cannabis Plants

What causes nutrient deficiency? There are numerous factors that may come into play regarding nutrient deficiencies in cannabis plants. However, the main reason for nutrient deficiencies is pH balance. Cannabis plants become sick when there is a deficiency in nutrients. While the disproportionate amount of nutrients may lead to toxicity and nutrient burn. (Ouch!) Nutrient deficiency may also cause a nutrient lock-out within the plants system.

Nutrients, What Are They?

Nutrients are vital for growth and overall lively hood of growing marijuana plants. Coincidentally, a cannabis plants life may be taken by nutrients that are improperly measured or added. The usual offenders for nutrient deficiencies are the 3 key nutrients used to grow thriving cannabis plants; Potassium, Phosphorus and Nitrogen. Although, nutrient deficiencies of zinc, calcium and magnesium may occur. However, these deficiencies are generally less common.

Of course deficiencies happen. But how does one ensure that nutrient deficiencies are avoided? Even though deficiencies happen. Regularly checking the pH of the water and if using soil. Checking the pH of the soil around the plant ensures that a healthy pH is maintained. Correspondingly, a healthy pH assures that the plant is receiving all the nutrients needed to grow into thriving cannabis plants.

Cannabis plants tend to like a neutral pH balance. The recommended pH setting for cannabis plants is between 6-7. To adjust the pH level of the growing medium, whether that be in soil or water. First the pH must be tested. Then determined if it must be made more acidic, or alkaline all depending on the pH level. If a nutrient’s added or taken away. This addition or subtraction has a direct effect on the pH levels. A general understanding’s key.

Nutrient Deficiencies in Cannabis Plants


Although phosphorus deficiencies are not regularly common. They do happen, more so in hydroponic systems. When a plants suffering from phosphorus deficiencies. The foliage begins to turn darker in colour, and the growth slows down. The leaves of the plant will change to brown. Then will begin to curve and curl. Some plants may even develop a blue or red hue.

Phosphorus deficiencies are dealt with by switching the fertilizer that’s being used. The new fertilizer should have a higher phosphorus level than was initially being used. Ensure that the fertilizer used is appropriate to the stage in which the plant is currently in. ie. Flowering fertilizers for the flowering stage.


Potassium deficiencies are more or less common amongst growing cannabis plants. But why? In fertilizers, potassium’s the least added ingredient. As potassium’s the nutrient that’s least required by cannabis plant. When a plants suffering from potassium deficiencies. The plant will appear to be doing fantastic. The plant may even appear to have grown quickly. However, check the lower foliage, as the leaves more than likely will have turned brown and be dying.

The cannabis plants growth may also appear to be quickening, and then slowing down. Bear in mind that potassium aids the plant in water and nutrient distribution. Hence why a large potassium deficiency could effect the entire plant. To fix a potassium deficiency, adjust the fertilizer that’s being used. Another route is to use a water soluble potassium additive.


Nitrogen deficiencies are common amongst cannabis plants as nitrogen’s heavily utilized within the plant. Nitrogen’s one of the most vital nutrients for optimal plant growth. As it plays a key role in processes such as photosynthesis and the construction of key amino acids. Generally, nitrogen deficiencies start from the bottom. Then work their way up. The leaves of the plant will begin to turn yellow. And if left alone, will wither and die.

Nitrogen deficiencies can be taken care of by checking the nutrients the plant is currently receiving to ensure the plants receiving the correct ratio of nutrients. During the vegetative stage. The cannabis plant will require a surplus of nitrogen to thrive. A quick fix for a boost of nitrogen to improve the plants health is done by incorporating bat guano or compost.


Iron deficiencies are not abnormal amongst cannabis plants. The first indication of iron deficiency will be in the new growth of the plant. Mostly in the leaves. The leaves around the top of the plant are generally the leaves that are most affected. These leaves will discolour and turn yellow, quite distinctively. Because iron plays a key role in the production of chlorophyll. An iron deficiency in plants will have yellow leaves, with green veins. Why? Because there just isn’t enough chlorophyll to sustain.

Iron deficiencies can happen at the same time as pH imbalances. As well, iron deficiencies occur alongside manganese and zinc deficiencies. So keep this in mind when determining the proper way to deal with the nutrient deficiency. To determine if the plants suffering from an iron or manganese deficiency. The difference will be that iron deficiencies affect the top leaves, and the new growth. While manganese deficiencies effect the bottom of the plant.


Magnesium deficiencies are more or less common in indoor grown cannabis plants. Including hydroponically grown plants. While outdoor grown plants are less susceptible to magnesium deficiencies. In most cases, the lower leaves leaves will be affected at the beginning. Where they will turn yellow and weaken. If left alone, the leaves will die. And soon after the deficiency will reach the crown of the plant. Magnesium plays a vital role in the production of chlorophyll within the plant.

The most common (and easiest!) cure for magnesium deficiency is through the application of epsom salts. Before adding epsom salts to the cannabis plants, assure that the real issue is a magnesium deficiency. Should any unnecessary minerals be added. Then the overage of minerals creates a completely different problem from the one being addressed. So make sure the diagnose is correct before attempting to rectify the deficiency.


Copper deficiencies are rather uncommon in cannabis plants. But if a copper deficiency does arise, a lot of damage can be done to the new growth. The first symptoms of copper deficiency will be in the new leaves. A symptom which is known as necrosis. The leaves will turn a brown, almost grey-blue colour. While new leaves, flowers and other areas may become weak and limp without enough copper.

Coppers a mineral thats conveniently renewed within the cannabis’s plants environment. And coppers vital for the cannabis’s plants ability to thrive and mature. For that reason regular checks are quite necessary. A handful of fungicides contain copper. However, there are other options available should fungicides not be an option.


Boron deficiencies in cannabis plants is a rare occurrence. While a boron deficiency is a rare occurrence. The deficiency can have negative effects on the plants growth. A visible sign that the cannabis plant’s suffering from boron deficiency’s when the plants growing tips begin to turn grey or brown. The overall growth of the plant will either slow down, or stop completely. The cannabis plants leaves may experience dead spots as well. These spots may not be visible as they would be scattered.

A boron deficiency should be dealt with as soon as possible. Adjusting the irrigation process and assuring the boron returns to the environment usually fix’s the problem. A common addition for most growers is Boric Acid. However, simple compost or other natural mixtures also work to adjust the levels back to normal.


Calcium deficiencies, similar to many other deficiencies are most common in indoor grown cannabis plants and hydroponic systems rather than outdoor grown plants. Most water supplies contain calcium. If the water does not contain calcium, calcium must be introduced by the grower. Cannabis plants are unable to thrive without calcium. Plants grown in a hydroponics system that only have water and nutrients in a solution, generally do not get the calcium needed.

Calcium deficient plants will have unusually dark leaves, with large dead patches. The old growth will show the most symptoms, with extremely weak branches. That, with any further stress, or weight added, could break or crack. If the deficiencies not properly addressed, issues could arise even in the root system. Calcium deficiencies come with a very simple method to address the deficiency. Growers take limes and squeeze the juice onto the soil or substrate, where the plant takes it from there.


Molybdenum deficiencies are extremely uncommon amongst cannabis plants. However if a molybdenum deficiency should arise. The outcomes are negative and unpredictable. When there is a molybdenum deficiency, the leaves at the middle of the plant turn yellow. And any new foliage growth is warped or there’s none at all. The tips of the leaves on the plant will acquire a strange crimson hue while the shoots of the plant begin to curl. Molybdenums primary reason for existence within the plant is for the production of ammonia. Deficiencies in the plant are extremely rare because the plant uses so little molybdenum. Therefore, when dealing with a molybdenum deficiency. Use caution. Infused solutions and sprays are generally favoured by growers.


Silicone deficiencies pretty much never occur in outdoor grown plants. But silicone deficiencies do occur in indoor grown plants. In the outdoors, silicones readily available. Likewise in nutrient solutions and fertilizers. Silicone is a key ingredient for plant production. Plants that experience silicone deficiencies will have weak branches and stems. As well, the photosynthesis production may be constrained. Silicone also aids in the plants protection against insects. Plants experiencing a silicone deficiency may show increased issues with insects.

There are a number of different options available to deal with silicone deficiencies. Preferred methods by growers for silicone deficiencies include liquid silicone or diatomaceous. Please note that silicone deficiencies are very rare. So check with an experienced grower before adding more silicone.


Sulfur deficiencies aren’t common amongst cannabis plant. Fertilizers come pre set with the appropriate levels of sulfur included. Hence, why sulfur deficiencies aren’t common. Signs of sulfur deficiency include stunted growth. Yellowing of leaves and new developing foliage. New leaves may appear to be more narrow and brittle than before. The most common (and easiest!) cure for sulfur deficiency is through the application of epsom salts or potassium sulfate. Before adding more minerals to the cannabis plants. Ensure that the real issue is a sulfur deficiency. The addition of unnecessary minerals creates a completely different problem from the one being addressed. So make sure the diagnose is correct before attempting to rectify the deficiency.


Zinc deficiencies are quite common, regardless of how little zinc the plant actually uses. Plants veins in older leaves will turn yellow and the foliage growth twisted when experiencing zinc deficiency. Another sign of zinc deficiencies when the plant appears to be getting paler. During the flowering stage, similar issues will appear on the buds. They may become deformed or curl. Generally, zinc deficiencies occur alongside manganese and iron deficiencies. The production of vital enzymes and plant development are just two of the important plant processes plays a key role in. Serious zinc deficiencies can cause the plants stem to wilt or even break. Ensure that the correct deficiencies are being dealt with always. As zinc, manganese and iron deficiencies all link together.