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Types of Cannabis Nutrient Deficiencies

3 weeks ago
5 min read
Types of Cannabis Nutrient Deficiencies

Growing cannabis is a lot of fun until your plants start dying without any rhyme or reason. Well, there certainly is a reason, but you don’t see it at that point of time. And, this can be very frustrating, especially if you’ve cared for the plants like they are your own children. Among the many problems ailing cannabis plants, nutrient deficiencies are the most common. 

Most cannabis plants suffer from one deficiency or another at one point of time in their lives. But, if you’re growing autoflowers, you gotta be extra careful because the plants don’t have a lot of time to recover. Sure, you can correct the deficiency, but you will lose precious time. Thus, focus more on how to prevent nutrient deficiencies rather than curing them. Read on to educate yourself about all cannabis nutrient deficiencies you should be aware of. 

Correct pH problems 

Before we talk about nutrient deficiencies, there’s one topic we should cover. And, it’s about the pH.  Plants absorb nutrients using their roots. But, it happens only if the pH is stable. If the pHis haywire, the plants simply cannot intake food, and this results in problems. Oftentimes, growers mistake pH issues as nutrient deficiencies but it’s actually a nutrient lockout or excess in nutrients that causes problems. 

When the pH of the medium you’re using to grow the plants becomes too alkaline or acidic, it becomes impossible for the plants to get to the nutrients. Therefore, if you see that your plant is stunted or just not growing properly, check the pH of the growing medium before you come to any conclusions. 

If you’re growing hydroponically, the pH should fall in the range of 5.5 to 6.5 while a range of 5.8 to 6.8 is acceptable for soil mediums. Note that coco peat also falls in the category of hydroponics. If you’re mixing soil with coco coir, you will need to maintain a standard pH of 6 to avoid any issues. 

Nutrient deficiencies



Nitrogen Deficiency (N)

Among the many nutrients cannabis plants love, nitrogen is considered the most important. Plants need nitrogen at all times during their life-cycle. Whether they are in the growing or reproductive stage, nitrogen is necessary. It’s the most common problem, and thankfully doesn’t take a lot of time to be recognized. 


At first, the leaves of the plant begin to look pale. Generally, healthy leaves are neither too light or dark in color. When the plants begin suffering from nitrogen deficiency, the leaves become lighter in color. The leaves at the bottom first turn pale and it then spreads to the rest of the plant. 

If it’s not treated on time, the leaves become yellow and eventually start dropping from the plant. You will see too many leaves falling off. Do not wait until this occurs. Another sign is the leaves may also display brown spots and curling. Basically, you’ll end up with a shortage of bud sites and premature flowering. In other words, the yields will be drastically less. 

Phosphorous Deficiency (P)

The next important nutrient is phosphorous. It aids in photosynthesis and releases energy to the rest of the plant. Phosphorous deficiency occurs mainly due to the pH going above 7. Thus, it’s important to keep the levels of pH at a good range before trying to solve deficiencies. When the plants have a deficiency of P, it makes them stunted. If younger plants are affected, it results in growth problems along with little to no resin production. They also take a long time to flower. Ultimately, the yields are less. 


Leaves and even stems turn purple. If left untreated, the purple color turns darker and even looks black at times. Eventually, the leaves curl and start dropping. You’ll also see purple or black spots on the leaves. 

Potassium Deficiency (K)

Potassium is responsible for transporting carbohydrates and sugars to the rest of the plant. It also helps in the development of the roots and it’s impossible for the plants to survive without potassium. Potassium deficiency raises the temperatures of the plants and the leaves begin to evaporate a lot more moisture in an effort to cool themselves down. 


The leaves look dull and also burnt at times. They appear rusty and lifeless eventually. You can also see the leaves turn yellow at one point. Due to dehydration, leaves begin curling and look like they are charred or burnt. At the end of it all, the yields decrease and the plants struggle to grow. 

Calcium Deficiency (Ca)

Calcium helps in holding the cell walls of plants. When there is a deficiency, the cell walls break down, resulting in distorted growth. 


Early symptoms show brown spots on the leaves and as it progresses, you’ll see darker spots. The leaves also turn pale while the tips look burnt. Since calcium is essential for growth, a deficiency results in stunted growth and less yields. 

Magnesium Deficiency (Mg)

Magnesium helps plants absorb energy from sunlight. It also helps the plant create sugars and carbohydrates that are crucial to develop flowers. It is present in every chlorophyll molecule, which means that the plants simply cannot do without it. 


The inner parts of the leaves turn yellow. Magnesium deficiency is pretty easy to spot. The veins of the leaves turn yellow from inside and spread to the outer areas of the leaves. Although it takes time for the plants to display this deficiency, it spreads throughout the plant quickly especially when it’s flowering.

Here’s a video explaining the most common cannabis deficiencies:

Sulfur deficiency

Sulfur helps the plants break down the fatty acids and also produce essential oils or terpenes. It usually occurs due to a high pH in the roots. 


The leaves turn a bright lime-green in color. After a while, they appear yellow while the veins also look yellow. The leaves become brittle and dry eventually. There will be a decrease in bud sites and the plants struggle a lot in the flowering or reproductive stage.

Copper Deficiency (Cu)

Plants need very small amounts of copper, yet it’s important. It helps to fix nitrogen and also in plant metabolism. 


The leaves may begin wilting. Although copper deficiency is rare, the leaves can begin to twist and appear distorted. You will see spots appearing on leaves and they slowly spread to all parts of the plant. 

Iron deficiency (Fe)

Iron helps the plants in chlorophyll production along with sulfate and nitrate reduction. The plants don’t need a lot of iron but it is crucial nonetheless. 


The veins of the leaves look yellow or lime-green in color. New leaves look yellow, and the deficiency that begins from the top spreads to the bottom parts of the plant. 

Manganese deficiency (Mn)

Manganese helps the plants utilize nitrogen. It also helps in absorbing iron and plays an important part in producing chlorophyll. Although it’s rare for plants to develop manganese deficiency, it commonly occurs when there is excessive iron or when the pH is very high. 


The leaves begin displaying a yellow color. You will also see mottled brown specks throughout the leaves. The symptoms begin with younger leaves but it spreads to the older leaves as well. While the outer part of the leaves or margins remain green in color, the inner parts appear yellow. 

Molybdenum deficiency (Mo)

Cannabis plants use molybdenum in small amounts but it’s a major player in converting nitrates into usable ammonium. The deficiency can occur when the climate is just too cold for the plants. 


While the center veins of the leaves look normal, there will be a discoloration of the veins spreading from the inner to the outer parts of the leaves. It’s also known as interveinal chlorosis and the leaf edges display a discoloration. 

Zinc deficiency (Zn)

Zinc helps in the production of proteins and sugars while retaining chlorophyll. It usually occurs when the levels of pH are too high. 


The tips of the leaves look burnt and brown. You will also see brown spots that spread to different parts of the plant. Zinc deficiency is very easy to spot because the leaves turn sideways.