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David Rhodes

David has been working in the cannabis industry for the past 17 years with experience working overseas in Amsterdam as a budtender for 5 years! Learn More About David!

Lack of nitrogen hampers the growth of cannabis plants resulting in reduced yields, an unwanted outcome when one is investing time and effort into cultivating cannabis. The signs of nitrogen deficiency are simple to spot, however, they can occasionally be mistaken for magnesium deficiency or potassium deficiency.

Nitrogen Deficiency In Weed:

Nitrogen deficiency in weed is an extremely common problem with grows, and it can cause your grow to die completely or have much smaller yields. If you’re going to spend the time and resources to grow cannabis, you should be sure that it’s healthy and has a productive yield!

Fixing the deficiency early enough is beneficial to prevent the leaves from falling off. If you want to improve your yield make sure that you treat the nitrogen deficiency as soon as you notice it.

nitrogen deficiency in weed

Do Marijuana Plants Need Nitrogen?

Nitrogen is necessary for weed plants especially during the vegetative stage. It is a mobile nutrient so it travels to different parts of the marijuana plant and is needed by the entire plant.

For proper growth of leaves, stems, and branches, your weed plant needs to have optimal nitrogen levels. If you are growing your marijuana plants outdoors, it is even more important that you check them for symptoms of nitrogen deficiency.

Severe Nitrogen deficiency can affect growth and in turn affect the quality of your harvest.

Here are some of the reasons why weed plants need nitrogen;

For Photosynthesis

Nitrogen is an important nutrient for photosynthesis. With the help of sunlight, chlorophyll, and sunlight plants can synthesis sugars. These sugars and carbohydrates are essential for plant growth and also give leaves the green coloring matter.

For Vegetative, Pre-Flowering, And Flowering Stages

Weed plants need nitrogen in almost all stages of growth. You might avoid nitrogen in the first two weeks of the plant but shortly after that, you need to start using the right nitrogen dosage. The nitrogen will promote fast growth and also help you to get a good yield.

For Increased Plant And Pest Resistance

Using nitrogen in your weed plants makes them resistant to pests and diseases such as spider mites. In cases where plant diseases occur, they are not severe and detrimental to plant health. Optimal nitrogen levels in weed plants will also make them resistant to frost when growing them outdoors.

Can You Prevent A Nitrogen Deficiency In Weed Plants?

Yes, it is possible to prevent too much nitrogen in weed plants! Proper preparation and monitoring of the plant at every stage can be beneficial.

Here are some of the ways to prevent nitrogen deficiency in cannabis plants;

Prepare The Soil With The Right Compost

If you are going to plant your weed plants in pots, it is important to prepare the compost. Ensure that it has the right balance of nitrogen before planting your weed plants.

Starting with the right compost can help you to avoid a lot of deficiencies in the growth process.

Continuously Check The Soil pH

Checking the soil pH continuously can also be effective. Most of the time when the pH is not right, it leads to deficiencies because most of the nutrients cannot be absorbed by the plant.

What Causes Nitrogen Deficiency In Weed Plants?

Nitrogen deficiency symptoms in weed plants include:

Low Nitrogen Level In The Soil

If your soil has a low nitrogen level, you are likely to experience nitrogen deficiency. When growing your weed plants outdoors in an open field, this might be a problem since, unlike potted soil, the soil is not tested for nutrients.

Extreme Cold or Heat

Extreme temperatures might be detrimental to plant growth and issues due to plant stress. It is advisable to grow your weed plants in a controlled environment like a greenhouse so that you can keep the temperature optimal.

Overfeeding of Other Nutrients

Overfeeding your weed plants with other nutrients is not advisable. It causes a scenario called nutrient lockout which affects the absorption of important nutrients like nitrogen.

Low pH

Low pH is detrimental to plant health and growth. If your soil has a pH that is lower than 5 then you are likely to experience nitrogen lockout. The nitrogen available in the soil will not be absorbed due to a low pH.

Damaged Plant Roots

Damaged plant roots are likely to cause nitrogen deficiency in your wood plants. If your roots have been damaged by fungus, then they will not be able to properly absorb nutrients.

Signs of Nitrogen Deficiency in Weed Plants

Nitrogren deficiency and excess nitrogen can be difficult to spot since it can look similar to other deficiencies. Below is a picture example of nitrogen deficiency in weed vs. nitrogen excess!

nitrogen deficiency in weed vs nitrogen excess

Some of the nitrogen deficiency symptom in cannabis plants include:

Yellowing of Leaves

Yellowing of leaves in weed plants is a sign of nutritional deficiency. However, in nitrogen deficiency, the yellowing will start at the lower part of the plant.

yellowing cannabis leaves from nitrogen deficiency

Yellowing that begins at the lower part of leaves is unique to nitrogen related issues, so this is a good sign of nitrogen deficient plants.

Curling of Leaves

If the nitrogen deficiency is not corrected, you’ll notice that the leaves will start to curl. They appear withered and start curling inside.

Dropping of Leaves

Weed plant leaves dropping is probably the last stage when you don’t address the deficiency. The leaves start dropping because the plant is now weak. It might start with the bottom leaves and move upwards.

Weak and Red Stem

Nitrogen deficiency affects almost the entire plant. Apart from visible signs on the leaf, you can inspect the stem for weakness and a red tinge. If the stem looks small, red, and weak, then this is a clear sign of a deficiency in cannabis plants.

Small Leaves and Short Plant

Since nitrogen is responsible for plant growth, you will notice that your marijuana plant has small leaves and suffers from suppressed growth.

Premature Flowering

Premature flowering is an uncommon sign of nitrogen deficiencies in marijuana plants. The plant starts flowering but the growth does not mature. Premature flowering leads to low yields.

How To Treat Nitrogen Deficiency In Cannabis Plants

Treat nitrogen deficiency as well as other nutrient deficiencies in weed plants through the following strategies;

Remove Affected Leaves

The first step is to remove the affected leaves. In case of nitrogen deficiency, the affected leaves are present at the bottom part of the plant so make sure that you trim them before you start the treatment process.

pruning yellow cannabis leaves

Removing the affected leaves is important to allow new buds to grow. The yellow leaves suck up nutrients so make sure that you remove them as early as possible. If you see leaves with rust spots, you should also get rid of these as well.

Fix Your Soil pH Levels

Fixing your soil pH levels can be beneficial to treat nitrogen imbalances in your cannabis plant. The best way to do this is to make sure that your soil pH is between 5.5 and 6.5. This optimal pH allows the absorption of nitrogen and other essential nutrients.

Fix The Nutrients

Once you fix your pH levels, it is time to fix the nutrients. The best way to go about it is to add the nutrients slowly so that you do not overdo it to prevent nitrogen toxicity.

There are several ways to fix nitrogen deficiency. Two common options are chemical nitrogen and organic nitrogen. Organic nitrogen is a better choice as it releases nutrients slowly.

Organic Nitrogen For Cannabis Plants

Organic nitrogen fertilizers are effective for cannabis plant growth. However, you have to be patient because they are released slowly and it takes time before you see results.

Some of the organic nitrogen options that you can use include; chicken manure, alfalfa pellets, coffee grounds, and planting legumes. It is advisable to use organic fertilizer early enough.

Urine is also a good source of nitrogen for marijuana plants.

Chemical Nitrogen Fertilizer

Using chemical nitrogen fertilizer for cannabis growth is another great option. Always make sure that you inject the chemical fertilizer in controlled amounts so that you do not cause toxicity.

You will start seeing results after a short time because nitrogen fertilizer works faster compared to its organic counterpart.

Grower Fertilizer

Grower fertilizer is effective in correcting nitrogen deficiency. It is important to use grower organic fertilizer that contains nitrate or ammonia.

These fertilizers are the best because they not only correct deficiency but also promote the fast growth of the plants and act as healthy plant food.

Nitrogen Toxicity In Weed

Nitrogen toxicity occurs in weeds when you have an excess of nitrogen in the plant. It is likely to occur at some point leading to a condition commonly known as “claw” in weed plants.

Signs Of Nitrogen Toxicity In Cannabis

The following are common signs of nitrogen toxicity in cannabis;

Curled Leaves At The Tip

In case of nitrogen toxicity, you are likely to see curled leaves at the tip. The leaves almost look like they have claws and thus the name.

curled cannabis leaves

It is easy to miss the presence of curled leaves so you need to check closely so that you find it.

Abnormal Green Color

Unlike the yellowing that happens due to deficiency, nitrogen toxicity also causes an abnormal green color. The green color is darker than usual. It almost looks purple. In some cases, the leaves might start drying out around the tips.

Slow Growth

Nitrogen toxicity is also likely to cause slow growth. The slow growth affects the flowering process eventually resulting in low yields.

Nitrogen toxicity is common when weed plants are grown in a controlled environment. New farmers tend to think the more nutrients they add the better the yield.

Unfortunately overwhelming your plant with nutrients only leads to toxicity.


What Causes Nitrogen Deficiency In Weed?

Nitrogen deficiency in weed is directly caused by bad or unhealthy soil lacking in nutrients. You should work to add nitrogen into your soil through nutrient boosters, coffee grounds, or nitrogen fixing plants.

Can nitrogen toxicity in weed plants be prevented?

It is possible to prevent nitrogen toxicity in weed plants. The secret is to know when to feed your plants with nitrogen. The best time to feed your plant is during the vegetative stage. At this stage, your plant needs a lot of nutrients.

Unfortunately, many farmers add more nitrogen during the flowering stage resulting in toxicity. If a plant experiences yellowing of leaves during the flowering stage, you need to know that it is normal and avoid panicking.

Is organic nitrogen better than chemical nitrogen?

There is always the debate on chemical vs organic nitrogen. The truth is that it depends on your needs as a cannabis grower and preferred farming guidelines.

Chemical nitrogen works well because you can measure the requirements for fast results. It is easy to use and available.

Organic nitrogen, on the other hand, works slowly because it releases the nitrogen gradually. It might take some time to see results but you do not have to worry about toxicity.

When is the right time to feed your weed plants with nitrogen?

Feeding your plants in the early stages isn’t recommended. The best time to start feeding your plants with nitrogen is after two weeks as it allows the plants to grow on their own so that the roots can develop naturally.

After two weeks, you can start feeding your plants with nitrogen. This should continue until the vegetative stage ends and the flowering stage begins. You will not need a lot of nitrogen during the flowering stage.

What form of nitrogen does cannabis prefer?

If you decide to go with the chemical way of feeding your cannabis plants with nitrogen, it is advisable to go with Nitrate-nitrogen. It is preferred for growing cannabis, especially in a greenhouse.

Nitrate-nitrogen is a little bit expensive when compared to other types but it is effective.

Is nitrogen deficiency common during weed flowering?

It is not uncommon to experience nitrogen deficiency during the flowering phase. During this phase, the plant is using a lot of nutrients and you will see the normal yellowing of leaves.

Most cannabis growers panic at this stage and start adding nitrogen fertilizer. If you have been feeding your weed plants during the vegetative stage, you do not have to panic.

Nitrogen deficiency in weed plants can be solved. You can use organic compost or chemical fertilizers to fix the deficiency. The trick is to feed the plant during the vegetative stage.

It is also advisable to be careful when feeding nitrogen to avoid toxicity. Using organic compost and chemical fertilizers correctly will fix the nitrogen deficiency.

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About David Rhodes

David has been working in the cannabis industry for the past 17 years with experience working overseas in Amsterdam as a budtender for 5 years! His goal is to help you with your cannabis grow! Learn More About David!

David Rhodes