nitrogen for cannabis

Nitrogen Deficiency vs. Nitrogen Toxicity in Your Weed

Nitrogen Deficiency vs. Nitrogen Toxicity in Your Weed

When it comes to a nutrient problem in your cannabis crop, you can do more harm than good if you don’t correctly identify the problem. Nitrogen is a critical component in the proper growth and function of marijuana. Understanding this macronutrient will equip you to grow high-quality cannabis while saving yourself stress if you encounter a deficiency or toxicity issue.

✅ Understanding Nitrogen’s Role in Cannabis

When I’ve gone to survey grow operations when I worked with a consultant agency, I found that the most common problem in marijuana gardens had to do with nitrogen. I can’t count the number of times that I’ve seen canopies as far as the eye can see that was a deep yellow. This nutrient is responsible for a host of functions within our beloved marijuana crop. Let’s take a look at what nitrogen is responsible for before we outline common problems.

First and foremost, nitrogen is a crucial component in the production of chlorophyll. Some of you may remember this term from biology class, so hopefully, this time you remember! Chlorophyll is the pigment that’s responsible for the plant’s green color. More importantly, it functions as a light-absorbing pigment that enables plants to photosynthesize the Sun’s rays into food.

Without this function, plants would not exist in their current form as they do today. This key adaption is what has driven plants all over the world.

Another function of nitrogen is its role in amino acids. Amino acids are the building blocks of proteins, and without these proteins, plants would not survive. Just like with our own bodies, we require proteins to function correctly, and it’s not different for plants.

All of the required nitrogen is taken up through either the root system or through foliar sprays. The form in which nitrogen is taken by the plant is either nitrate (NO3) or ammonium (NH4). These two forms are essential to remember, but even more important is to understand the dosage.

Remember, nitrogen is the main component for your plant to produce new leaves. Besides the root system, the cannabis canopy is crucial for the survival of your cannabis plant. The leaves are the engine, the light is the fuel, and the chlorophyll is combustion. Nitrogen allows for all of these critical components to happen, so it’s with the utmost importance that you take the time to understand and respect the role of nitrogen fully.

🎯 Feeding Cannabis Nitrogen

If you’ve grown weed, then you’ve seen all the cannabis nutrient products and their display of the macronutrients N-P-K. N stands for nitrogen, the other two are phosphorous and potassium, but we’ll focus on the other two in another series.

As your cannabis plant begins to grow and uptake nutrients, the available supply of nitrogen will decrease. This means that you’ll need to feed your cannabis plant nitrogen continually. Of course, the type of nitrogen you feed your plant is dependant on the method in which you’re growing.

The most straightforward method is to buy nutrients that are considered “safe.” This means that buying a bottle of plant fertilizer that consists of an N-P-K of 10-10-10 is generally a safe standard. The reason for this is because all marijuana strains have different nutrient needs, and a gentle 10-10-10 ratio is best for starting out.

Nitrogen is quickly absorbed through cannabis, and you’ll notice fairly quickly if you gave too little or too much. Let’s take a look at identifying problems related to nitrogen.

👾 Nitrogen Deficiency

Nitrogen deficiency has to be one of the most common problems that growers face. Suddenly your marijuana plant is turning yellow. You don’t understand why the lower leaves are beginning to wither and die off, but you do see it as a problem. Before you go throwing more plant nutrient, stop and identify the problem.

It’s common that growers do more harm than good when they blindly start adding things to their cannabis crop without first identifying the issue at hand.

The biggest giveaway for nitrogen deficiency is the yellowing of lower leaves. The reason this occurs is that the plant has run out of available nitrogen to uptake. This causes higher leaves that are closer to the light to steal the lower leaves’ nitrogen. If left alone, the lower leaves will eventually fall off, and the problem will continue from bottom to top until the plant cannibalizes itself in search for nitrogen.

You’ll know if your plant is recovering if the yellowing doesn’t continue and leaves begin to regain their healthy green shade. Light green is always a sign that a nitrogen deficiency is close to happening.

The worst time for a nitrogen deficiency is at the beginning of the vegetative stage, where the plant is focusing on growing foliage that will help once the flowering stage begins. Alternatively, it’s at the end of flowering that growers tend to intentionally create a nitrogen deficiency to rid the plant of chlorophyll.

Now that you’ve identified the problem, increased the dosage of plant nutrient, you should wait a few days to confirm if your plant is recovering. Remember, patience is half the battle when it comes to growing marijuana.

The Only Time You Want a Nitrogen Deficiency

There is, in fact, a time when you actually do want a nitrogen deficiency. The only time you’ll ever want this as a marijuana grower is during the end of the flowering stage. Depending on the strain, you want your cannabis leaves to turn yellow around week 8-10 of flowering.

But why? This is a situation that is very specific to growing marijuana because it all has to do with the end product. You guessed it- it has to do with the buds that we’ll eventually smoke after the drying and curing process.

Chlorophyll as we learned, is the necessary pigment in absorbing light. Near the end of the flowering process, we’re going to sadly kill our plants to harvest them. The issue with chlorophyll is that this pigment as contains a smell similar to hay or dry grass, which we taste when smoking the finished product

Lack or excess of nitrogen in your marijuana

The easiest way to get rid of this smell and taste is by flushing out as much of the chlorophyll as possible. Growers will usually start only watering their plant with small amounts of nutrient to force a nitrogen deficiency. This is extremely apparent when you look at pictures of growers harvesting their plants. What you’ll see is large buds and most of the leaves a bright yellow color.

This isn’t an essential step because you can also get rid of excessive chlorophyll during the drying process. All you’ll need to do is leave your plants in complete darkness for a few days to speed up the dissipation of chlorophyll from the leaves.

⚠️ Nitrogen Toxicity

The opposite of a nitrogen deficiency is when we see nitrogen toxicity. This is equally as common as nitrogen deficiency because new growers tend to overdose their plants with nitrogen. It’s a fact that new growers kill their cannabis plants by loving them too much.

It’s common that growers cause nitrogen toxicity by following even the recommended dose found on their nutrient product. The recommended dose offered by nutrient companies is just a general amount because some strains will need either more or less. Once again, no strain is created equal, and this means that each strain you grow will more than likely require varying dosages of nutrient.

When encountering a nitrogen toxicity issue, you’ll see a deep shade of green on the leaves of your marijuana plant. The deep shade of green can worsen and even take on a slight deep blue hue in extreme cases. This is a very noticeable symptom and is therefore easy to identify and fix before real damage occurs to your cannabis plant..

Another noticeable symptom of nitrogen toxicity is called the “claw.” The ends of the fan leaves will point down, similar to the way a bird claw looks. This symptom is also present when overwatering cannabis plants, but if you’re not overwatering, then this should lead you to believe that you’re amid a nitrogen toxicity issue.

To add to the list of symptoms is also leaf tip burn. When too much nitrogen is added, the plant tries to get rid of it through the ends of the leaves. This results in the leaf tips looking necrotic and seemingly burned.

Nitrogen: excess vs. lack

If nitrogen toxicity is allowed to continue,then the plant will cease many necessary functions to sustain vigorous growth. You should never let a toxicity issue to gain a foothold on your plants because it will result in a more extended recovery period.

It’s dangerous to suddenly stop giving nutrients when noticing a nitrogen toxicity issue because the plant is still up taking the other necessary nutrients. If you stop giving nutrients, you may find yourself in the exact opposite situation: a nitrogen deficiency!.

Small steps are vital in not creating a bigger problem. Adding or decreasing nutrients will take a few days to show results.

🔥 The Role of pH and Nitrogen Issues

As we all know, there are a host of problems that can go wrong while we’re growing our marijuana crops. A major complicating factor for nitrogen toxicity or deficiency is when it’s accompanied by pH issues.

Depending on the medium that we’re growing in, pH plays a vital role in the health of our plants. This is extremely apparent when growing in hydro or aeroponic systems. These systems don’t have the natural buffer found in soil-grown plants. Cannabis grown in soilless systems rely on their caretakers to set the pH to a correct level that allows the plants to take up plant nutrient effectively.

If you don’t set the pH to a correct level (usually 5-6pH), then you’ll compound your problems as you see deficiencies or toxicities starting to mount up. The root zone doesn’t enjoy the wrong pH and will stop taking up nitrogen, thus creating a nitrogen deficiency.

📖 Conclusion

These are just a few examples of the intricacies of growing marijuana. Most aspects of the plant are interconnected, which leads to one problem affecting another portion of the plant.

For marijuana plants to develop smoothly, the pH and dosage must be continually monitored.

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Nitrogen Deficiency In Cannabis Plants

We explore what a nitrogen deficiency looks like in your weed plants. Read on to learn how to solve this issue and prevent the occurrence from happening altogether.


Growing cannabis is a therapeutic act that takes quite a lot of attention to detail. One of the requirements to successfully grow a large cannabis crop of good quality is applying the right concentration of nutrients. If your plant begins to lack the required amount of nutrients during any point of the grow cycle, it may begin to exhibit symptoms of deficiency. If left untreated, these deficiencies may cause harm to the plant’s health and reduce yields.


One of the most important nutrients that your cannabis plants need is nitrogen. Nitrogen is vital for plant health because it is a major component of the green pigment found within plant leaves known as chlorophyll. Chlorophyll plays a crucial role in photosynthesis, the process by which plants convert sunlight into energy in order to survive. Nitrogen also serves as a major component of amino acids within plants, which are the building blocks of proteins. Nitrogen is also an important component of nucleic acids like DNA, which plants need in order to grow and reproduce.


It is quite clear to see how important nitrogen is to your cannabis plants and why a deficiency could be so damaging. Luckily, nitrogen deficiency is quite easy to detect if you know what to look for.

One of the key signs of nitrogen deficiency within your weed plants is yellowing leaves. The older and lower leaves on your plants will start to become yellow, wilt, and drop off. This is because the younger leaves higher up the plant will start to steal the nitrogen from these older leaves. The plant prioritises higher leaves as they receive the most light, contributing greatly toward photosynthesis.

This may not always be a concern. It is normal for these lower and older leaves to start becoming yellow and dropping off towards the end of the grow cycle as nitrogen is diverted toward the buds. It is time to worry when your plant’s leaves start to yellow and drop off rapidly during the vegetative phase. If this yellowing starts to move up the plant in a climbing manner, then a problem is most likely present.

A solution to this problem is to provide your plants with a balanced nutrient product. There are many formulas available that provide an array of key nutrients to your plants, making sure that nitrogen levels are kept at a healthy level all the way through the vital vegetative phase.


Some novice growers may be shaken at the sight of nitrogen deficiency symptoms, causing them to go overboard when adding nitrogen to their soil. However, be forewarned: the pendulum can swing the other way when it comes to nitrogen, with too much also causing a problem in plants.

When a grower accidentally puts far too much of the nutrient into their soil, it can cause the phenomena of nitrogen toxicity. During the vegetative phase of the grow cycle, it is rare that plants will develop nitrogen toxicity unless a huge amount is given to them. Nitrogen toxicity is more common during the flowering phase, as plants require lower levels of nitrogen at this point. Symptoms of toxicity can manifest in shiny leaves, much darker green leaves, weak stems on plants, much slower overall growth and clawing of leaves. Clawing is a typical occurrence that involves the tip of leaves losing vigour and folding downwards, resulting in a claw-like appearance.

Nitrogen is a key nutrient within cannabis plants and is required for many processes. Here is how to detect a deficiency, with some helpful solutions.