List of Cannabis Deficiencies: How to Prevent & Cure Them

Cannabis plants are similar to other types of plants as these are not immune to nutrient deficiencies. And as an aspiring expert cannabis grower, you must understand and prevent the many different nutrient deficiencies in cannabis plants and know how to cure in the event of any kind of problem. 

Take note that to be able to grow healthy plants with good yields, you must learn how to diagnose simple cannabis deficiencies. Here are a few of the most common nutrient problems that cannabis growers encounter. 

What are Cannabis Nutrient Deficiencies?

Cannabis plants require a certain amount of nutrients to survive. If their nutrient needs are not met, this can result in a nutrient deficiency. 

Nutrients can be divided into macronutrients and supporting nutrients. Macronutrients are Nitrogen, Potassium, and Phosphorus. These three come in varying amounts and are needed in varying amounts as well. Meanwhile, supporting nutrients are available in minimal amounts but are nonetheless important in cannabis plants’ regular functions. 

A deficiency is present when a nutrient is in small amounts. Meanwhile, toxicity is when the nutrient is present in large amounts. Both a deficiency and toxicity are bad for your plants. Your cannabis plants may end up with poor growth and low yields when any of these nutrients are overlooked.

What Causes Cannabis Deficiencies?

There are different causes of nutrient deficiencies, consider the following:

• Improper use of fertilizers and supplements – the most common culprit in nutrient deficiencies is the incorrect use of fertilizer and supplement. Failure to read and understand directions on how to apply the fertilizer product can lead to severe supplement problems. Using incorrect fertilizer according to the growth phase of the plant is a common problem. 
•  Cannabis plants have two major growth phases: the growing or vegetative phase and the flowering or the blooming phase. Plants need fertilizer with higher amounts of nitrogen than potassium or phosphorus during the growing phase while during the blooming phase, plants require higher potassium than phosphorus to help buds grow larger and denser. Forgetting this number one rule can easily affect your plants’  growth.

 Also, consider how the fertilizer or supplement is applied to plants or soil. Not following simple instructions could affect the life of your plants. 

Nutrient lock in the roots and soil – a condition is known as nutrient lock may affect the way your plants take in nutrients. Nutrient lock happens when there is an excess nutrient that settles in the soil or the roots. This nutrient or mineral can block nutrients from being absorbed causing the nutrients to pool in the roots and plants.

• Nutrient toxicity leads to nutrient deficiency – similar to how to root lock or nutrient lock develops in the roots, when a nutrient is present in toxic amounts, the plant is unable to take in some nutrients. There must be a balance in the plant’s metabolic system otherwise, it may not be able to utilize the supplement or nutrients you are giving it. 
• Unhealthy soil – in some cases, the soil used to grow cannabis may not be good enough to use. Acidic soils may affect the way some nutrients are absorbed. Some soils may be too compact like loamy soil and thus, this won’t be able to absorb fertilizer and nutrients and this leads to deficiencies. Also, soils that are too loose like sandy soil or soil with more sand content may not be able to hold nutrients. 

List of the Most Common Nutrient Deficiencies, their Cure and Prevention Tips

Here is a list of some of the most nutrients and their corresponding ways on how to deal with their deficiencies. 

Macronutrients

The three macronutrients are the foundation of your cannabis plants. Having a healthy balance of these nutrients gives your plants a fighting chance of growing larger and denser plants. And with all problems that marijuana plants encounter, the soon you find out about it, the easier you can keep your plants healthy and have a higher chance of a good harvest. 

Nitrogen 

Nitrogen is a very important nutrient in plant growth and is widely used therefore it’s not so surprising that it’s easy for plants to develop nitrogen problems. This macronutrient is used in various processes including the manufacture of amino acids needed for plant growth and development as well as chlorophyll as plant food. 

With nitrogen, your plants can grow taller, develop more leaves, stems, and roots and can prepare for the growth of larger and denser buds. As you can see, with less nitrogen, all these processes will be affected. Your plants will remain small and with sparse leaves. Adult plants will not be able to develop good and strong parts to hold buds for the flowering stage and there is also a possibility of delayed blooming time. 

Nitrogen deficiency symptoms

• Changes in the older leaves from the base to the middle part of the plant
• Yellow leaves
• Yellow leaves can wither and die
• Yellowing and withering can progress to the top, new and healthy leaves
• Even after the deficiency is solved, the yellow leaves won’t return to their green color

Nitrogen deficiency treatments

Treatment should be done ASAP otherwise, it may be too late. You must find a way to naturally increase nitrogen and the following can help.

• Use natural supplements with high nitrogen amounts like blood meal, dried blood, bat guano or bat manure, cottonseed meal, fish meal, worm castings, and many more.  
• Use fertilizer with correct amounts of NPK. Take note that plants need higher amounts of nitrogen during the vegetative stage. 
• The test pH level of soil and correct if there are any problems.

You can tell that your plants are recovering when the yellowing of the leaves has not progressed. The yellow leaves will soon wilt and die but new and green leaves will take their place.

Phosphorus

Phosphorus deficiencies are more common in hydroponic systems than in soil-grown plants because the soil is known to have high amounts of phosphorus.

This nutrient is responsible for the growth of roots and for boosting the strength of leaves and stems during the vegetative stage. It prepares the plants in growing large and dense buds. Phosphorus also helps in the germination of seedlings and is very important during the flowering phase.

If there is a phosphorus deficiency during the flowering phase, your plants will grow smaller buds and thus you’ll have smaller yields. 

Phosphorus deficiency symptoms

Check for the following symptoms:

• Plants will slow down their growth and will look very frail.
• The foliage is darkening.
• Leaf edges will change from green to brown and will start to curl inwards.
• The petioles will become dark sometimes turning from green to blue or reddish.
• Symptoms appear during the coldest days because it’s during this time when cannabis plants are having a hard time absorbing phosphorus stored in the soil. This can also occur when the soil is too wet or moist and in soil that’s too alkaline.

Phosphorus deficiency treatments

The following may be used to treat phosphorus deficiency

• Use fertilizer with higher phosphorus content. Apply this especially during colder climates. Take note that as long as the phosphorus ratio is higher than 5 then you can use the product to correct phosphorus deficiency.
• Use organic materials to solve phosphorus deficiencies: use bat guano, an organic material with high amounts of phosphorus.
• Use only water-soluble fertilizers for maximum effectiveness.
• Use all-purpose plant supplements like Miracle-Gro but use only half of the recommended dose. Using more can kill your plants.
• Use other organic materials like worm castings, bone meal, and bat guano. Crab shells also work but these are expensive.

As with nitrogen and potassium, the effects of your treatment are noticeable after a week. The affected leaves will never recover and return to its regular form and color but new leaves will soon replace these. You will also notice that the symptoms of a phosphorus deficiency have ceased which means your plants are on the road to recovery.

Potassium

Low levels of potassium are quite common when it comes to growing cannabis plants. This happens because, in most fertilizer products, it has the lowest ratios compared to most macronutrients.s 

But just like nitrogen and phosphorus, this nutrient is very important in the growth, health, and development of cannabis plants. Potassium is necessary for water respiration, an important process in plants. It is also a nutrient that’s important in a plant’s natural resistance to different diseases. 

Potassium is also vital during photosynthesis as the plant makes food for his use. Also, potassium is helpful in water circulation. It helps water move through the plant which is necessary for the vegetative and flowering phases. 

Potassium deficiency symptoms

You may find potassium deficiency symptoms rather unusual but you should treat your plants the moment you notice the first signs of potassium deficiency.  

• Your plants will grow taller faster and will look healthy except for the lower part of the plant.
• The lower leaves turn brown and die. The leaves may seem to have burnt edges and tips.
• Your plants will soon slow down its growth, especially the leaves.
• Mature leaves will appear yellow and mottled in between the veins but soon, the entire leaf will be affected.
• Some leaves may also become completely yellow and soon die. 
• Delayed flowering phase and very poor yields.
• Irregular growth in some areas

Potassium deficiency treatments

Despite all the weird and irregular symptoms of potassium deficiency, there’s good news. This is one of the easiest nutrient deficiencies to correct. Remember the following

• Use a fertilizer that has more potassium compared to the one you’ve used before.
• Adjust the fertilizer you are using before by adding a water-based or water-soluble potassium. 
• You may also use organic substances like wooden ashes, granite dust, kelp meal, or try sulfate of potash. 

Results your efforts can be readily seen after a week. Same to nitrogen and phosphorus deficiencies, the affected plant parts will never return to their previous states. But you can tell that the treatments are working if the symptoms have ceased. 

Other nutrients

Magnesium

Magnesium is necessary for the development of strong and healthy plants.  Cannabis plants need this nutrient for vein health and the creation of new leaves. Magnesium is utilized for producing chlorophyll.

It is rare for outdoor growers to encounter magnesium deficiencies because it’s a very common nutrient in the soil. This is usually a common occurrence in hydroponic systems. The deficiency starts at the lowest parts of the plant leading to the loss of many leaves. This is why you must deal with magnesium deficiencies right away.

Magnesium tends to move around the body of the plant therefore the symptoms vary and can be seen on different parts of the plant. This is the reason why magnesium deficiency can show up at the bottom of the plant especially on the older leaves causing theses to die. 

In severe cases, magnesium deficiency can move up from the bottom leaves to the top of the crown of the plant. This element is vital for the plant’s food manufacturing so don’t overlook early signs.

Magnesium deficiency symptoms

In magnesium deficiency, the symptoms start at the bottom of the plant. Remember the following:

• Lower leaves begin to yellow and will soon show chlorosis.
• Leaves will curl inward and will soon fall and die. 
• Leaf outline will become dry and very brittle.
• Soon, growing shoots will become light green and then become white.
• The petioles and the stems will turn purple.
• Red stems may also be seen but this is uncommon 

Magnesium deficiency treatments

Treat magnesium deficiency as soon as possible with any of the following:

• Use plant booster products with high levels of Magnesium. Read labels well and apply the correct dose.
• Use organic products to cure magnesium deficiency: dolomite lime, Epsom salts, worm castings, garden lime, or magnesium sulfate. We recommend using Epsom salt or Magnesium sulfate since these are water-soluble. Epsom salts are best for hydroponic systems. 
• To use Epsom salts use a ratio of a gallon of water: a teaspoon of Epsom salts. 
• Use Calcium- Magnesium product or Cal-Mag. This is a trusted Magnesium and Calcium corrector that is available in most cannabis growing supplies shop. 
• Correct root pH. Incorrect pH can lead to poor absorption of nutrients. Keeping the correct root and soil pH can help prevent the occurrence of any deficiency. Also, adding magnesium supplements to roots or soil with incorrect pH won’t do any good. The nutrient will simply stay in the soil and this can affect the absorption of other nutrients. Remember, when you’re growing in soil root pH should be from 6.0 to 7.0 and when you’re growing in hydro, root pH of 6.0 to 6.5 is needed for efficient Magnesium absorption.
• Flush your system with clean, pH-balanced water. Flushing will help remove nutrient salts which may affect your plant’s ability to absorb Magnesium and other nutrients. Also, this can help improve pH and maintain pH correctly.

It can take a week for magnesium treatments to completely work. Expect that the affected plant parts will never recover but new growth will eventually appear to replace these old growths. 

Boron

Boron deficiency is rare. However, the first sign of boron deficiency should be treated right away. This deficiency is mostly due to the absence of this nutrient in the soil or in the fertilizer or supplement that you use. It is also possible that some nutrients present in high amounts in the roots are affecting the absorption of boron. But despite being a minor nutrient, boron deficiency can also affect the growth of cannabis plants.

Boron deficiency symptoms

You’ll notice the following in plants with boron deficiency:

• Tips of leaves change color from green to brown or gray.
• There is slow growth.
• There are small dead spots that may be isolated in some parts of the plant but may also be scattered in different areas.

Boron deficiency treatments

Fix boron deficiency right away to avoid damaging effects to plants. 

• Adjust root and soil pH since incorrect pH can lead to poor absorption of boron and other minerals.
• Use boric acid. This can help fix boron deficiencies and is the most common treatment used by cannabis growers.
• Use compost or organic materials as these may also contain substantial amounts of boron.

You will know that your boron deficiency treatment is working when the symptoms are not progressing. The damaged leaves will not return to their regular appearance but new, green, and strong leaves will soon grow. Depending on the treatment you used, it can take days to a week before your plants can recover.

Calcium

Calcium deficiencies are common in cannabis plants grown indoors in hydroponic systems. It is also a common deficiency in areas where calcium is not added to local water irrigation systems. If you are using a hydroponic system and adding nutrients to water in your reservoir solution then you may be forgetting a good calcium source. Also, incorrect soil and root pH can lead to calcium deficiency. Overlooked calcium deficiency can lead to frail plants, poor growth, and reduced yields.

Calcium deficiency symptoms

You’ll find the following in plants with calcium deficiency:

• Symptoms begin on the older leaves
• The presence of big dead blotches on very dark leaves.
• Very weak branches that easily break.
• Overlooked symptoms can lead to root problems
• Poor growth and possible poor yields

Calcium deficiency treatments

Thankfully, calcium deficiency is very easy to treat. Just use any of the following.

• Use lime to correct calcium deficiency. Follow the directions as to how to use lime products to get positive results.
• Use Cal-Mag, a calcium and magnesium product that effectively corrects calcium levels without harming your plants.
• Correct pH levels of soil or the roots because any incorrect reading can affect the absorption of calcium and other minerals.

You can tell that the calcium treatment that you used is working when the symptoms of calcium deficiency are no longer progressing. However, the leaves and stems/branches affected will never return to their previous appearance. 

Copper

Copper deficiencies are very uncommon but overlooked copper deficiency can lead to poor growth and poor new growth of leaves. Despite being a minor nutrient, copper is needed by plants to grow, make food, and to create dense and big buds. 

Copper deficiency symptoms

The following is present in plants with copper deficiency:

• New leaves start to wilt and die.
• Leaves appear brownish, blue, or gray at the tips.
• New growth like leaves, stems, and flowers will look very frail.  

Copper deficiency treatments

Here are a few practical ways to treat copper deficiency:

• Use fertilizer products rich in copper. 
• You’ll find products like fungicides which have higher copper amounts.
• Fix incorrect pH amounts to ensure the proper absorption of copper and other minerals

The affected parts will never return to their previous states and will only wilt and die. You will only be able to tell if the treatment you’re using is working when the symptoms are no longer progressing.

Iron

Iron deficiency in cannabis plants can be seen in new growths most especially the leaves. Therefore, the upper leaves are most affected and are usually discolored. The symptoms of iron and manganese deficiencies may look the same but iron deficiencies affect new growths.

You must correct iron deficiencies right away because these may affect the growth of your plants and can also reduce yields. Take note that iron plays a huge role in chlorophyll production in cannabis plants.                                                                                                                                                                                    

Iron deficiency symptoms

Check for the following symptoms of iron deficiency:

• Upper/newer leaves will change color from green to yellow.
• The new leaves will change to yellow but the veins will remain green.
• Plants will look very weak and sickly, yields will be affected.

Iron deficiency treatments

Consider the following when correcting iron deficiency: 

• Fix incorrect pH levels in the soil and roots. Incorrect pH levels can lead to poor absorption of nutrients such as iron. 
• Iron deficiencies usually occur when there are manganese and zinc deficiency.  Treat these conditions alongside iron deficiencies.

Once iron treatments have been provided, it takes only a few days for your plants to recover. You can tell that your plants are slowly recovering as the symptoms are no longer progressing. Sadly, the affected parts will never return to their previous condition. New growths will soon replace these affected parts. 

Manganese

Manganese deficiency is uncommon and will usually occur together with zinc and iron deficiencies. This mineral is needed in food production in plants as it is vital for chlorophyll and in the creation of nitrates. Take note that too much manganese can lead to iron deficiency. 

Manganese deficiency symptoms

You should notice the following when your plants are suffering from manganese deficiency:

• Symptoms are common in new plant growth most especially in the leaves.
• Leaves will have dead spots which will soon turn yellow. 
• Plants will appear weak and may have slow growth.

Manganese deficiency treatments

Consider the following when treating manganeses deficiency in cannabis plants:

• Use manganese in the water-soluble form to correct deficiencies.
• Use compost or a product known as greensand to help correct manganese deficiencies.
• Improve soil and root pH because these often lead to poor absorption of nutrients like manganese.

Correct manganese treatments will work in a few days and you can tell that your plants are recovering when the symptoms of the deficiency are no longer progressing. The affected parts will never recover. New healthy growth will only replace them.   

Molybdenum

It is uncommon to have molybdenum deficiencies in cannabis plants but this can happen whether you’re growing your plants in soil or hydroponics. Only a very small amount of this nutrient is needed to support the growth and development of plants but the absence or very low amounts of molybdenum can cause devastating effects to plants. 

Molybdenum deficiency symptoms

You’ll find the following symptoms in cannabis plants with molybdenum deficiency:

• Symptoms concentrate on the new leaves or foliage.
• The middle leaves turn yellow and new leaves will become warped and will stop growing.
• The shoots curl inwards.
• The leaves will change color from green to red especially along the lips.
• The plants will have slow growth and will have diminished yields.      

Molybdenum deficiency treatments

Treat molybdenum deficiency with the following techniques:

• Use molybdenum supplements. Use only half of the amount recommended since cannabis plants need only a small amount of this nutrient.
• Use sprays or molybdenum-infused solutions to treat this kind of deficiency
• Check soil and root pH since incorrect pH can lead to poor molybdenum absorption as well as other nutrients.

You can tell that molybdenum treatments are working when the deficiency symptoms are not progressing. The affected plant parts will never return to their previous appearance but will simply wilt and fall from the plant.

Silicon

Silicon deficiencies are often found in indoor hydroponic systems this is because this nutrient is abundant in nature. Silicon is needed in plant production and development and thus, deficiencies can lead to poor plant growth and development. It is also needed in the natural pest control properties of cannabis. You will soon  notice that pests are more plentiful 

Silicon deficiency symptoms

You can tell that your cannabis plants lack silicon when you notice the following:

• The presence of insects/pests. All kinds of pests attack your plants compared to other plants you have in your garden.
• Weak stems and branches. 
• Poor growth and poor yields

Silicon deficiency treatments

Silicon deficiency is very rare in plants therefore you should be cautious in applying a treatment. Always check for the presence of other nutrient deficiencies or causes before suspecting silicon deficiency. 

Silicon deficiency is treated by any of the following:

• Use silicon supplements. Follow instructions carefully and be sure to give only the required amount.
• Liquid silicon is always the best formula so it can move through plant roots easily.
• Diatomaceous earth
• Pest control products to control pests that can ruin your plants and your yields. 
• Check and correct root and soil pH. Sometimes silicon and other nutrients cannot move through the roots because of incorrect pH. 

After providing proper silicon treatments, it can take a week for your plants to recover. You can tell that the treatment you used is working if you find that the symptoms are not progressing. The affected leaves and stems will never recover however new and healthy ones will take their place.

Sulfur

Sulfur deficiency is very rare because most fertilizers have adequate amounts of sulfur. But sometimes, the poor absorption of other minerals and incorrect pH can affect the absorption of sulfur. 

This nutrient is important to many cannabis plant’s vital processes such as food manufacturing, growth of the root system, and overall development.

Sulfur deficiency symptoms

You can tell that your plants have a sulfur deficiency when you find the following symptoms:

• Yellowing of the new stems and leaves 
• Narrower and brittle new leaves
• Stunted plant growth
• Poor yields

Sulfur deficiency treatments

Take note of the following sulfur deficiency treatments:

• Use potassium sulfate
• Use Epsom salts
• Correct root or soil pH to allow nutrients to be absorbed by plants

When sulfur deficiency treatments are applied correctly, it can take days for your plants to recover. Don’t expect an instant fix. You will notice that the symptoms are not progressing and this means that you have successfully overcome this problem.

Also, the affected leaves and stems will never return to their previous appearance. New and perfect foliage will simply grow to take their place.

Zinc

Cannabis plants require very small amounts of zinc but most of the time, zinc deficiencies occur. This can happen during the growing phase of the flowering phase as well. Usually, zinc deficiencies can occur together with iron and manganese deficiency.

Cannabis plants need zinc to support many plant processes such as the development and creation of different enzymes. 

Zinc deficiency symptoms

You can tell that your plants have zinc deficiency when  you spot these symptoms:

• Twisted foliage 
• Veins of older leaves turning yellow 
• Soon, the plant loses color and become pale
• Small buds with very poor yields
• Buds could become deformed or curl inwards
• Wilted stems, weak stems that break

Zinc deficiency treatments

Consider the following treatments when treating zinc deficiencies:

• Check for other deficiencies like manganese and iron deficiencies and treat these as well.
• Check the pH of roots and soil. Some nutrients cannot cross the roots because of incorrect pH.

Be careful in trying to apply zinc supplements because plants need only a small amount of this nutrient. As with all nutrient deficiencies, it can take days before your plants recover from zinc deficiency. The affected stems and leaves won’t recover but new foliage will surely grow to replace the diseased ones. 

• Water-based or water-soluble potassium. 
• You may also use organic substances like wooden ashes, granite dust, kelp meal, or try sulfate of potash. 
• Results your efforts can be readily seen after a week. Same to nitrogen and phosphorus deficiencies, the affected plant parts will never return to their previous states. But you can tell that the treatments are working if the symptoms have ceased. 

Conclusion

Cannabis deficiencies happen in indoor or outdoor growing areas. You must prevent and take extra care when applying fertilizer or supplements and never overlook any kind of symptoms no matter how minimal it may be. Cure nutrient deficiency to help your plants achieve good health and good yields.