What Is Nutrient Burn In Cannabis Plants And How To Fix It?

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Added 31 May 2022

Growing cannabis is fun, but it comes with its own set of challenges. One of the most critical factors in growing cannabis is to provide it with the right nutrients. Good nutrients can make a world of difference. They can make your buds dense, big, and juicy to beat.

But, just like everything in life, too much of anything is too bad. Feeding your plants with excess nutrients can be hazardous to the plants, no matter how much you love them.

Once beginners understand that the magic formula to growing big buds lies in the nutrients, they overfeed their plants with so many nutrients that the plant struggles to absorb them.

In just a few days, the plants begin displaying various symptoms, from burnt tips to yellowing leaves. But, if you're lucky, you can still salvage what's left of the plant, depending on its growth phase.

In this article, you will know everything about nutrient burn, from what causes it to how you can prevent it and what you can do if your plants are already struggling with it.

What is nutrient burn?

nutrient burn

Nutrient burn in cannabis, or any other plant, refers to the stress plants experience when you feed them with excessive nutrients. Cannabis plants need nutrients in appropriate ratios for healthy growth; however, they are exposed to extreme stress when you exceed those ratios.

Overfeeding cannabis plants is a problem most beginners deal with. Since beginners believe their plants will grow bigger and better by feeding them with nutrients, they tend to overfeed them, hoping for massive yields.

Although nutrients play a crucial role in growing plants with the ability to produce extraordinary yields, it's important to remember that plants don't function like animals. For instance, animals, or even humans, for that matter, gain weight when overfed. However, plants and their needs are different.

Rather than growing huge when you overfeed them, they will display signs of distress instead. They also follow a particular schedule, including the seedling, vegetative or the growing phase, and finally, the flowering phase. Each phase requires nutrients in different proportions. When you feed inappropriate ratios during any of these stages, the plants will start suffering.

Also called "nute burn" in cannabis communities, nutrient burn occurs when the cannabis roots absorb more nutrients than they can use. Excessive nutrients block the plant's water flow, leading to brown tips that almost look burnt.

The good news is that the signs are so evident that you can salvage most of your yield before it's too late. However, if you are unobservant and don't take care of it on time, the problem will spread inwards and cause the leaves to twist and become crispy. If it goes out of hand, you'll end up with little to no yields.

Symptoms of nutrient burn

Nutrient burn

As mentioned already, the plant displays pronounced signs of nutrient burn. At first, the leaves of the plant will appear dark green. Most beginners will assume that this is a sign of healthy growth, but it will take some experience distinguishing between healthy and unhealthy cannabis leaves. Darker green leaves usually mean trouble.

Next, the leaf tips become brighter and even translucent at times. You can solve most nutrient burn cases by paying attention to the leaf tips. In addition, the tips will curl downwards.

Apart from looking at the fan leaves, you must also pay attention to the newer leaves. Not only will they grow very slowly, but they will also begin to turn yellow and crispy. The tips of the sugar leaves will either turn bronze, yellow or brown, and the leaves will eventually die.

As the problem progresses, you'll also notice spotting on the leaves. Typically the spots will be brown, yellow, or bronze in color. In addition, you'll usually see the spots on the edges of the leaves and their serrations. Another sign of nutrient burn is that the stems may sometimes appear purple or red.

As mentioned earlier, you can take care of nutrient burn and prevent it from progressing further and destroying the plant. But, the affected parts will remain the same, which means that the burnt leaves will look the same even if the plant gets better eventually. 

Another thing you should remember is that nutrient burn can be severe depending on what stage the plant is in. Now, you know that cannabis goes through several phases, including the seedling stage, vegetative stage, and flowering stage. 

So how does nutrient burn affect the plant in each of these stages?

How does nutrient burn affect cannabis in each stage?

Seedling stage

seedling stage

You should never feed the plant with nutrients for at least two weeks since germination. But, if you have to, you can go for nutrients meant specifically for seedlings and use only a quarter-strength of nutrients to ensure that the plant isn't overwhelmed.

The plant is very fragile in the seedling stage, and you should let it do its own thing rather than feeding it with nutrients.

If you somehow manage to overfeed the plant during the seedling stage, it will take a very long time for the plant to recover. In some cases, the plant may not recover at all.

Also, chances of recovery are greater if you're growing photoperiod plants than autoflowering plants. Photoperiod plants may bounce back despite a few challenges, but autoflowering plants may display stunted growth and yield nothing.

In conclusion, you must never mess with cannabis plants when they are still in the seedling stage, whether you're growing photoperiod or autoflowering plants.

Vegetative stage

vegetative stage

The plant focuses primarily on growing more leaves and healthy stems in the vegetative stage. When you feed them with nutrients, the plant puts out more leaves and all its energy to be strong enough to bear buds later.

The nutrients you feed during the vegetative stage vary depending on what you purchase; however, they are usually high in nitrogen. Thus, you'll see a higher N in the NPK ratios. Some growers feed a 3:3:3 or 4:4:4 ratio, which is perfectly fine.

If you overfeed the plant during the vegetative stage, the leaves will turn a darker shade of green. However, the situation is not so bad that it will affect the yields yet. You can still salvage the situation by being observant and cutting down on nutrients.

It's a good idea to flush all the nutrients from the system and start fresh again. Of course, the plant will need at least a couple of weeks to recover, depending on its genetics and health, but it's not the end of the world.

Again, we are strictly talking about photoperiod plants here. Autoflowering plants will produce minimal yield if you mess up even during the vegetative stage.

Flowering stage

flowering stage

The flowering stage, however, is a different matter. Unlike the vegetative stage, where the plant still has a chance to recover, the flowering stage may not be so forgiving.

The flowering stage is when the plant is the most vulnerable because it has very few chances to recover. The plant stops focusing on the leaves and stems and puts all its energy into making buds.

In addition, if you overfeed the plant during the early flowering stage when there are just a few pistils, the plant may still recover. But, if you feed it with excess nutrients when it is too far into the flowering stage, the plant will struggle to recover and may also die. This means that as the plant gets close to its harvest period, it doesn't make efforts to recover from damages.

Therefore you need to be careful with feeding nutrients during the flowering stage. That said, slight nutrient burn even during the flowering stage may be okay, but if the leaves get burnt or twisted, and the buds stop fattening, you're out of luck.

Also, different kinds of cannabis strains have different needs for nutrients, so make sure you read the seed bank's instructions carefully before feeding them.

Common causes of nutrient burn

You already know that nutrient burn occurs when you overfeed your cannabis plants. It usually happens when you feed the plants with bottled nutrients containing high amounts of minerals and chemicals.

Commercially bottled nutrients help cannabis plants grow very healthy. In fact, you get massive yields, especially when compared to organic nutrients. Plant roots tend to absorb chemical-based nutrients easily since you're feeding appropriate ratios. As a result, the plants don't have to work harder to intake them. However, the disadvantage is the plant can sometimes absorb much more than needed when the levels of nutrients in your bottled nutrients are excessive.

This is not to say that your plants can't experience nutrient burn while growing in organic soil. Sure it can happen, especially when you use soil containing excessive nutrients.

For instance, let's talk about homemade compost. Making compost is a slow process where it takes months for the organic matter to decompose. It's a process that requires heat and time. 

When done correctly, you'll end up with high-grade compost the plants love. However, if you rush up the process, the nutrients can be too hot for the plants. In simple terms, aged compost is much better than fresh compost. 

The same theory applies even to manure. Whether you use manure derived from cows, sheep, or even horses, they have to age well for the plants to use the nutrients. Therefore, fresh manure can be detrimental to the plants.

Also, if you've perused a few cannabis forums, including our Growdiaries, you've probably heard of super soil. Making super soil involves mixing several types of manure and other amendments to create rich fertile soil. 

However, you can't use fresh super soil immediately as it will be too "hot" for the plants, just like fresh manure or compost. Thus, it's recommended to fill only a quarter part of your container with super soil and fill up the remaining with regular soil so that the plants don't experience nutrient burn. 

Cannabis plants can also experience nutrient burn if you have low-quality lights. Typically, cannabis plants will be able to withstand slightly high nutrient levels if they have enough light.

Some growers assume that their cannabis plants experiencing a nute burn is good because it implies that they are providing extra food to their plants. However, this is a myth because the light is what your plants need the most. 

On the other hand, nutrients act like extra amendments or supplements. The plants can survive for quite a while even if you don't add nutrients, but they will quickly die if there is no light. Without light, there is no photosynthesis, and without photosynthesis, there is no way for the plant to produce energy to develop leaves.

Therefore pay attention to the lights you're using and ensure that the plants get adequate light to fight against other problems. Depending on your setup, space, and requirements, you can use both LED and HID Lights. Both types of lights are great for the plants to produce ample yields. 

Other problems that mimic nutrient burn

It is easy to confuse nutrient burn with other problems, including:

Nitrogen toxicity

nitrogen toxicity

Nitrogen toxicity affects cannabis plants in various ways. Typically the leaves will turn very dark green, and they may also appear waxy in texture. Some plants may also display leaves that look like claws since they bend unnaturally at a 90-degree angle.

Nitrogen toxicity occurs when you feed the plants with excessive nitrogen. Plants experiencing nutrient burn can also sometimes have claws since they could be suffering from nitrogen toxicity. 

In short, some plants may be experiencing both nitrogen toxicity and nutrient burn simultaneously. While nitrogen toxicity occurs due to excessive nitrogen alone, nutrient burn occurs when there is a combination of many nutrients and not nitrogen alone.

Nutrient deficiencies

potassium deficiency

Many nutrient deficiencies, including potassium, iron, and even sulfur, display yellowing leaves and burnt tips at times. Potassium deficiency, in particular, can cause the leaf margins to turn yellow. Over time, they can become brown and appear like they are burnt.

Other deficiencies like sulfur, for example, mimic nutrient burn. In addition, sulfur deficiency appears like nitrogen deficiency at times, so it is challenging to distinguish one from the other. 

The only way to differentiate between the deficiencies is to check the source of the problem. For instance, if the deficiency is spreading from the bottom to the top, it is likely nitrogen deficiency. On the other hand, it could be an iron deficiency if it spreads from top to bottom. But when the leaves appear burnt, it looks like a nutrient burn.

Some nutrient deficiencies will also cause the leaves to turn bronze or brown, along with spots on the leaves. Furthermore, the tips of the leaves will also curl or bend. If you cannot figure out the problem, it's best to flush the plants and let them rest for a while. Then, after a week or so, you can start feeding them half-strength nutrients with pH-balanced water.

Light stress

Light stress

It is very easy to confuse light stress with nutrient burn because light stress also causes the leaves to turn yellow. The leaf tips may look burnt. Light stress occurs when you place the lights too close to the plants. 

One obvious factor that distinguishes light stress from other issues is that light stress damages only the tips of the buds or leaves. You'll notice that the leaves closest to the lights suffer the most. However, if it's a nutrient burn, the entire plant will start showing signs of stress as opposed to light stress.

pH fluctuations

pH imbalance

It can be tough to differentiate between pH fluctuations and nutrient deficiencies because they look similar. Incorrect pH can also cause spotting on leaves. If you don't correct the issue soon, the leaves can turn crispy and look burnt, identical to nutrient burn.

A simple way to check for a pH imbalance is to check the runoff water of your container. If the pH is off, flush the plants and start over again.

How to fix nutrient burn?

As mentioned already, one of the easiest ways to overfeed the plants is to use bottled nutrients. It's easy to mix in a little extra. And if you feed a little extra during every feeding, the plants will begin to struggle with a nutrient lockout, which means they cannot absorb the nutrients. 

To prevent a nutrient burn when using bottled nutrients, first ensure you purchase nutrients from trustworthy manufacturers. The nutrients should be high quality and preferably designed for cannabis plants. For instance, several growers use nutrients meant for tomato plants, and while that could work, there is a chance of overfeeding your cannabis plants. 

In addition, follow the manufacturer's instructions closely. However, some companies advocate feeding more nutrients than the plant requires, but this is not advisable. 

The best way is to check the nutrient ratios with other companies to determine if you're on the right path. Take a look at the feeding charts to find out if you are overfeeding your plants at any stage. In fact, it is a good idea to start with fewer nutrients than recommended to see if your plant likes it. 

Like we humans need some time to adjust to changes, the plant will also require a while to get used to the new nutrients you feed them. If your plant does well, you can slowly increase the strength of the nutrients as the plant matures. You can also speak to fellow growers here to find out what works for them. 

Most importantly, you must feed nutrients according to the plant's growth stage. For instance, the plant will need more nitrogen in its vegetative or growing stage, whereas it needs little to no nitrogen during the flowering stage. Therefore if you feed nutrients meant for the vegetative stage during the flowering stage, the plant will experience stress and nutrient burn. 

If you're growing your plants in soil or coco and notice signs of stress, you should flush the system thoroughly with clean pH-balanced water and check the runoff. You should also check the pH frequently to ensure the plant isn't experiencing sudden pH fluctuations. If you're using old compost and natural soil and there's no problem with the soil, but you still see signs of stress, you need to wait for the plant to correct itself. Over time, the plant will use the extra nutrients and recover. However, the damaged leaves possibly won't recover. 

If you're growing your plants in a hydroponic system, check the pH before taking any steps. If the pH is fine, drain all the water and start fresh with fewer nutrient levels. Use your TDS meter and begin with the lowest possible levels of nutrients until the plants recover. Again the damaged leaves will not recover, but you should be successful in stopping the nutrient burn from spreading further.

In any case, it's easy to fix a nutrient burn if you notice it early. However, if you're frequently running into such issues, it's time to change the nutrients you're using. 

Summary: What Is Nutrient Burn In Cannabis Plants And How To Fix It?

Nutrient burn is a fairly common problem, especially for overzealous beginners who feed more nutrients than required to their cannabis plants. A cannabis plant, like every other plant, has a few requirements, but it will perform much better than you imagine even if you feed fewer nutrients. 

On the other hand, feeding more than necessary can often force nutrient lockout and prevent the plant from absorbing more nutes. 

Nutrient burn can occur if you use bottled nutrients with high nutrient levels. It can also happen if you use fresh compost and raw manure. Therefore, it's recommended that you only purchase nutrients from trusted suppliers and use aged manure and compost. 

To fix nutrient burn, you must first flush your plants thoroughly with lots of water and check the pH of the runoff water. Next, start by feeding your plants with half-strength nutrients until the plants recover. Although the damaged parts of the plant may not recover, the plant will bounce back and produce good yields. 


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