Sulfur Deficiency in Cannabis Plants

While cases of sulfur deficiency cannabis are rare, you must know how to spot the signs that your plant lacks this macronutrient. Sulfur is essential for root development. It also plays a vital role in the development of plant proteins during the vegetation stage. 

Sulfur deficiency in cannabis plants is known to start at the back of the leaf. It then slowly progresses and moves to the tips. 

If you suspect that your plants have a sulfur deficiency, we have compiled a guide that will explain how to fix this issue.

Sulfur Deficiency Cannabis
Sulfur Deficiency in Cannabis

How Do You Identify Sulfur Deficiency in Cannabis?

To grow marijuana, you have to consider several factors if you need high and quality yields. Supply your plants with the necessary nutrients during the vegetative and flowering stages. 

If you are a marijuana grower, you might have noticed some of the characteristics of sulfur deficiency cannabis. If you are not careful or keen enough, you could mistake sulfur and nitrogen deficiencies; they have similar characteristics. You need to develop a habit of monitoring your plants regularly to know when the symptoms start appearing. 

Unlike nitrogen deficiency that appears when the plant is older, you’ll see sulfur deficiency symptoms when the plant is approaching maturity. The plant’s leaf changes appearance; it starts to yellow in the middle section of the leaf, and then it moves up to the tips. 

Here are some signs you should look out for if you are uncertain about if your cannabis plant has sulfur: 

  • Leaves turn lime green to yellow on the edges
  • Plants start portraying stunted growth
  • Leaf tips may hook downward
  • Leaves will turn pale/dark in color 
  • Stalk appears woody
  • Retarded bud development
  • Roots appear brown or slimy
  • You start noticing bugs
  • Plant starts drooping
  • Wilting leaves
cannabis sulfur deficiency
Cannabis Sulfur Deficiency

What Causes Cannabis Sulfur Deficiency?

Let’s look at some of the causes of sulfur deficiency in cannabis.

  • Improper supply of nutrients: Failure to supply your cannabis plant with the right amount of nutrients means it won’t get the right amount of sulfur. In most cases, this could result in sulfur deficiency in cannabis.
  • Overwatering your plant: Supplying your plants with too much water during the growth stages can cause sulfur deficiency. Water moves the sulfur down the soil, where the plant roots cannot access it. Plants with young and shallow roots suffer the most. Overly saturated soils lack the right amount of sulfur needed by the plants.
  • Poor soil quality: Lack of enough sulfur content in the soil outdoors can lead to sulfur deficiency.
  • High pH: High pH content when growing cannabis in a hydro setup can lead to sulfur deficiency in the plant. 

If you fail to take any actions, you could end up running into a condition known as a sulfur lockout. This condition occurs when the pH level rises above the normal level; this causes the soil medium to become Alkaline for the plant roots. This condition stops the uptake of sulfur by the roots of your marijuana plants.

Keep in mind the following PH values and ensure you don’t surpass them.

  • If you use soil as the growth medium, ensure the PH levels are 6.5 and above.
  • If you are using hydro and soilless mediums, the Ph levels should be 6.5 or higher.
Sulfur Deficiency in Cannabis

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The Importance of Sulfur to Cannabis

Sulfur is a minor nutrient requirement for the marijuana plant. A cannabis plant only needs sulfur in small amounts for it to survive. Sulfur plays a huge role, especially when it comes to the growth and development of the marijuana plant. 

Also, sulfur contains the contents of amino acids. Amino acids are essential since they help the plant to build proteins and grow strong and healthy. Sulfur also plays a role in the photosynthesis process. This process is crucial in a plant’s growth stage. 

Photosynthesis refers to the process of turning natural sunlight into food and energy. Sulfur helps the plant to absorb and convert light. Essentially, this is beneficial for the plant since it will have more energy to convert into food. 

Sulfur is also helpful when it comes to the plant absorbing and using nitrogen. Nitrogen is an essential nutrient for cannabis plants when it comes to growth and development. That is why both sulfur and nitrogen deficiencies have similar characteristics. The main difference between the two is that sulfur deficiency has some distinct symptoms that nitrogen deficiency lacks.

Below is an overview of the roles that sulfur plays during the growth of your cannabis plant. 

  • Sulfur promotes root development
  • Sulfur encourages chlorophyll production and distribution in a cannabis plant.
  • Sulfur enhances plant metabolism.
  • Sulfur promotes a plant’s overall growth and boosts plants’ health.
  • Sulfur promotes water and nutrient absorption.
  • Sulfur is essential for the formation of oils and flavors of cannabis plants.

Most of the roles mentioned above are important, especially during the vegetative stage. However, sulfur is also vital during the flowering stage. Sulfur deficiency might cause the buds to die and fall off from the plant.

On the flip side, having too much sulfur will reduce the growth rate of your plants. The plant leaves will appear brown on the tips and wilted. That said, avoid supplying your plants with too much sulfur since it has some damaging effects.

Sulfur Deficiency in Cannabis

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What Are the Signs That Show Excessive Amounts of Sulfur?

To know if your plant has too much sulfur, look out for the following signs. 

  • The growing medium will become acidic, lower than PH5.
  • Excess sulfur blocks the absorption of other essential nutrients like phosphorus.
  • Leafs will turn brown and have dark spots.

How to Fix Excess Sulfur

Follow the steps below if you want if your cannabis plant has excessive amounts of sulfur.

How Do You Fix Sulphur Deficiency in Cannabis?

If you would like to learn how to fix sulfur deficiency in cannabis, follow the steps below.  

The steps involved in correcting sulfur deficiency are not as cumbersome as many growers might think. The best part is: There are several products that you can use to correct sulfur deficiency after you spot it. They include:

Potassium Sulfate

Potassium sulfate is found in cal/mag and is necessary for plants to thrive and survive. It contains the nutrients potassium and sulfur. These nutrients are essential if you want to grow healthy marijuana plants with high yields. This component has the following benefits to your marijuana plants:

  • Boosts growth
  • It improves the plants’ drought resistance capability
  • It helps in pest control
  • It helps improve the yields
  • It promotes strong, healthy growth

The lack of this component in adequate amounts will cause the plant to be fragile, and the leaves will turn brown or yellowish. It is an essential requirement if you desire to have healthy plants. 

Sulfur Deficiency in Cannabis

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Ammonium Sulfate

You should apply ammonium sulfate if you notice any sulfur deficiency symptoms. This product is affordable, and it contains sulfur content, which is vital for the growth of your plants.

Magnesium Sulfate

Magnesium sulfate has outstanding benefits to marijuana plants. And this is a natural way that we recommend to supply your plants with both sulfur and magnesium. When added in appropriate amounts, nothing can go wrong during the developmental stage of cannabis plants. 

It is affordable, easy to use, and highly soluble in water. That makes it a perfect way to boost your plant’s growth. However, adding it in excess amounts can affect the plant adversely. Most importantly, you can use it successfully when growing marijuana in hydroponic systems.

Ammonium Thiosulfate

Thiosulfate is known by many weed farmers for being highly soluble in water. Ammonium thiosulfate can be mixed with urea to produce a highly sulfur-content fertilizer. After application, ensure you give the plant 3-4 days before waiting for results. For a positive effect, the leaves will start regaining their green and healthy color.

Elemental Sulfur

You can also opt for elemental sulfur if you intend to correct the sulfur deficiency in your plants. Elemental sulfur consists of 90% sulfur and 95% clay binder. Also, you can add elemental sulfur to a fertilizer mix.


Gypsum is affordable and is made up of calcium sulfate. It is suitable for soil correcting soils that are experiencing sulfur and calcium deficiency. It contains 15% of sulfate, which is easy for the plants to absorb.


Manure can be successful when it comes to providing plants with sulfur. For instance, manure from livestock is likely to have a sulfur content of 0.25% to 0.30%. However, poultry manure is known to contain a high level of sulfur. It has a sulfur percentage of 0.50. 

Keep in mind that fertilizers are not the only sources of sulfur for plants. Here are some of the other sources that can provide the sulfur needed by crops.

Organic Matter

Sulfur undergoes several microbial processes for it to become available for plants. The processes are highly dependent on the conditions that a plant can thrive well. Plants grown in cold soils are likely to suffer from sulfur deficiency since there is minimum microbial activity. 

Warm soils provide the perfect environment for growing marijuana plants because they will increase microbial activity. And this will ensure sulfur is available for plants.

Atmospheric Deposition

Industrial pollution, for instance, the burning of fossil fuels causes the emission of high sulfur content. Marijuana grown in such areas benefits from the emission of sulfur in the atmosphere. This is made possible by the precipitation of sulfur dioxide or sulfates. Lastly, the air pollution control methods that have been put in place are contributing to the decline of atmospheric sulfur for your plants.

Sulfur Deficiency in Cannabis

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To sum up, sulfur deficiency is one of the rarest conditions. Your plant needs sulfur because of various reasons. 

It’s easy to notice sulfur deficiency in your plant since its leaves will start experiencing color change: The leaves will turn yellow or orange, and the buds will dry off. 

Most growers mistake these symptoms for nitrogen deficiency. Always be on the lookout for any color change on your marijuana plants. Any slight color change can indicate that the cannabis plant has a sulfur deficiency. 

When a plant is experiencing sulfur deficiency, take the necessary action before you get disastrous effects on your yields.

As a marijuana farmer, you need to learn how to spot the symptoms of sulfur deficiency cannabis from a young growth age. Monitor your plants frequently for any signs of sulfur deficiency. This habit will help you get rid of the deficiency at an early age and get high-quality yields

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