11 Reasons Your Cannabis Leaves Curling Up [Get Instant Solution!]

Some of the most common causes for the curling or clawing of cannabis leaves are overwatering, nitrogen toxicity, temperature, bad soil, etc.

But mostly, newbies find it hard to diagnose.

Cannabis leaf curling is an issue that can occur to anyone growing it, irrespective of expertise.

Therefore, cannabis leaves curling, or “the claw,” is one of the most common issues that need to be addressed immediately to save the plants and yield.

Today’s guide will dive deep into the 11 reasons why your cannabis leaves are curling and find the instant solution.

Let’s get started, shall we?

Why Your Cannabis Leaves Curling?


As reported by most growers, these are the most likely to be a reason for cannabis leaf curling up.

However, you need to remember that there may be more than one reason for not doing things right.

Therefore, you must be very smart while diagnosing your weed plant.

Let’s have a closer look at these reasons:

11. Over-Watering


Cannabis leaves curling up suddenly?

Excess water can be the reason!

One of the most common reasons for cannabis leaves curling up is overwatering. That means you are watering your plants more often than they require.

It usually happens with newbie growers mostly.

In the excitement to grow plants quickly, they water them more frequently, damaging their plants by it.

During overwatering, the excess amount of water that you put into your plant rinses away most of the required and beneficial microbes from the medium.

Additionally, suppose you overwater your plants consistently for a few days.

In that case, it can also lead to the issue of root rot, which heavily damages the overall growth and yield of your plant.

So, root rot is an additional issue that comes as a bonus with overwatering.

Due to overwatering, the plants will look droopy, and their leaves will curl. However, if you can observe these symptoms on your cannabis plant’s leaves, it most likely can be due to overwatering.

However, you also need to confirm your watering schedule and know if this is the exact reason.

Instant Solution For Overwatering:

Overwatering is a common issue among growers, but the good part is that you can have an instant solution.

You need to maintain an effective way to dry-cycle to solve the issue of curling cannabis leaves.

Also, observe your plants to see if they need frequent water or if they are good to go with a once or twice-a-day schedule.

Further, you also need to observe your watering habit if you are doing it more frequently. If you are doing so, you must stop and water your plants properly to reduce the impact.

One of the most popular ways to determine whether your plants need to be watered is by picking them up and feeling their weight.

However, if your plants are in containers you cannot remove, you must invest in a good moisture meter.

So, by combining these techniques and your observation skills, you can easily make your plants overcome the issue of overwatering and stop curling leaves.

10. Under-Watering

Like overwatering, underwatering plants can also be another reason for curly cannabis leaves. And not to mention, over and underwatering causes similar symptoms in the plants.

This issue usually occurs with the growers, who are more likely to stay busy in their work life and can’t give proper attention to their plants.

As you underwater your plants for some regular days, they start to suffer and appear weak.

Observing the container is the best way to determine if your plants are underwatered. For example, if the surface level soil of the container is dry, your plants need water.

The only good thing about underwatering is that it will not cause root rot due to heavy water flowing through the roots.

That means your plants are safe from root problems due to water.

But that does not mean it will not affect the overall yield. Also, underwatering can lead to heat stress due to less moisture availability.

Therefore, if your plants are curling leaves, you need to observe if you are underwatering them and take necessary action immediately for their better health.

Instant Solution For Underwatering:

Once you observe that your plants are underwatered, you need to water your plants frequently.

You can decide how frequently you need to water your plants by your regional temperature.

But make sure that you are not watering again too frequently. Instead, make a balance between watering frequency, and after a few days, you will observe that your plant is now recovering.

9. Over-Fertilization

We all know fertilizers are important factors in the faster growth of your plants.

But you also need to know that they can harm your plants if not given the right dosage.

Constant extra doses of fertilizers can lead your plants to have nutrient toxicity. Nitrogen, phosphorus, and potassium are the most likely factors for nutrient toxicity.

Nitrogen toxicity is the most common.

When you overdo it with phosphorus and potassium during the flowering stage, it leads marijuana leaves to curl with scorched tips.

In such cases, Chlorosis symptoms can also occur.

Instant Solution For Overfertilizing:

Once you diagnose your plants with overfertilizing issues, you need to find an instant solution to avoid its impact on the yield.

There are two main solutions for an issue with fertilizers:

  • First, get a quality fertilizer like ILGM fertilizers
  • Second, maintain a balanced dose of fertilizers for your plants and avoid excess fertilizer

Sometimes, having a cheap fertilizer or nutrient solution and feeding it to your plants can also lead to several issues with cannabis plant growth.

In some cheap fertilizers, nutrient unbalance and excessive chemical composition to boost growth can hamper plant growth instead of helping it.

Therefore, go for a quality fertilizer or nutrient solution to help your plant produce a great yield.

However, the second solution is in your own hands.

Feed your plants only that much that they need. Don’t overdo it for the sake of yield. Overdose of fertilizers can reduce yield instead of boosting it.

So, do it with responsibility. Ideally, you can read a guide on feeding fertilizers to marijuana plants according to different growth stages.

8. Heat Stress


Heat-stressed plants will also start to show symptoms of leaves curling.

Weed plants need a temperature range of around 20 degrees Celsius. Anything above that will cause harm to the plant’s health, and therefore, it can lead to heat stress.

Heat stress can lead to the curling of marijuana leaves. Also, light burn and heat stress go hand in hand if you don’t pay attention to them.

If you observe the cannabis leaves turning brown on edge, it is a sure sign of heat stress, possibly due to excess light schedule or closer implantation of grow lights to the plants.

Also, outdoor growers growing cannabis plants outdoors and living in a warm region can most likely face this issue with their plants.

Instant Solution For Heat Stress:

Heat stress can easily be controlled using grow lights and maintaining a healthy light cycle.

Growers mostly use LED grow lights which are quite good and produce full spectrum light necessary for plant growth.

However, keeping the grow lights near the plants can cause heat stress and lead them to curling leaves.

Hence keep the light at an appropriate distance.

Indoor growers growing indoors in a grow room or grow tent can also use the fans inside grow tent or grow room to maintain a healthy temperature for cannabis plants.

Also, if growing outdoors in a warm climate, maintain a healthy routine for light and dark schedules.

7. Low Temperatures

Likewise, if the temperature in the growing environment is too cold, it will still harm the plants and ultimately lead to curling weed leaves.

Due to low temperatures, you will observe leaf discoloration symptoms on your plants. And that is a sign that you need to act for the same.

Prolonged exposure to low temperatures under 10 degrees Celsius can eventually kill the cannabis plants.

Therefore, you need to keep the temperature in the growing environment optimal.

Once you diagnose that the temperature in the grow room or grow tent is too low, you can have these solutions to make your plants happy and healthy instantly.

Instant Solution For Low Temperature:

If you are growing weed plants indoors, you can put multiple grow lights in the area to maintain temperature and avoid weed leaves curling.

Again, mind the appropriate distance of the lights to the plants.

However, if you are growing weed plants outdoors, you should consider harvesting early or moving your cannabis plants inside when it is too cold.

Keep in mind that you need to maintain a temperature range in the growing area of around 20 degrees Celsius.

You can follow these steps to do so.

6. Nitrogen Toxicity


In simple terms, nitrogen toxicity is when your cannabis plants get too much nitrogen. It is correlated with over-fertilizing.

Therefore, nitrogen toxicity happens when the nutrient levels in your cannabis plants increases.

That means you may put more than the required nutrients into the plants.

You can observe on your cannabis plant’s leaves the dark green spots curled up, showing a symptom of nitrogen toxicity.

Again, this happens with the growers who instantly want growth or want to increase the yield. However, now you know that adding extra fertilizers can cause toxicity and ultimately decrease the yield.

Instant Solution For Nitrogen Toxicity:

Don’t over-fertilize your plants. Instead, use quality nutrients with a limited dose.

The best practice is to start slowly with the nutrients.

However, if you are overdoing it for several days and want to remove the excess nitrogen from your plants, you can use a flushing agent or simply water.

In other words, you need to flush the growing medium with pure water to remove its extra nitrogen.

Correcting the pH level can also help your plants to recover.

5. Mg Deficiency In Plants


Magnesium deficiency is one of the most common deficiencies related to nutrients. It happens when there is a bottom-to-top nutrient imbalance in the marijuana plants.

You will observe your plants unhealthily.

The oldest and lowest leaves will show magnesium deficiencies. Leaves will turn yellow, and tips will dry out and become crunchy.

The bad part about it is that it starts spreading up in the plant if it is left so.

Once this issue spreads to the shoots, it will eventually turn purple, and chlorosis symptoms may also occur.

Therefore, with magnesium deficiency, you need to react quickly to save your cannabis plant.

Instant Solution For Mg Deficiency:

In case of magnesium deficiency, you must start by adding supplements or a flush of 6.0 pH water. Next, prepare a feed with the maximum pH for your growing medium.

You can use the specific nutrients as well according to the need.

With this, you can solve the issue. However, if you are completely unaware of this and need a detailed solution, then you must read an expert guide or ask for the help of a grower friend.

4. Wind Burn

Windburn is another issue that can cause your cannabis leaves to curl. However, in the case of windburn, the curling of leaves happens downward.

When plants are exposed to too much wind curl their leaves downward to defend themselves.

Therefore, too much wind is also the reason for cannabis leaves canoeing.

You may also observe dark areas on plant leaves which will be the symptom of burns caused due to heavy wind.

If you have too strong a fan blowing hard, it may lead to windburn.

Instant Solution For Wind Burn:

The solution for windburn is simple:

  • Lower the speed of the fan that you are using.

No doubt, a running fan keeps the temperature in optimal range but remember that a heavy wind flow can cause windburn to your plants.

Also, you can set your fans on a certain angle so that it does not directly hit the plant. This way, you can maintain the temperature and prevent your plants from windburn.

3. Light Burn

Light burn and heat stress are correlated with each other.

Growers with an indoor setup are more likely to face these issues as they are more prone to light burn due to growing lights.

When the plants are kept too close to the grow lights, it can lead to light burn; thus, your plants will start curling up their leaves.

In this case, the curling occurs towards the top of the plant or wherever it is closest to the light source. Similar to heat stress, the leaves will become yellow and curl.

Instant Solution For Light Burn:

If you have put the grow lights near the plants, you can keep them a little away at the appropriate distance.

Also, you must maintain the optimal temperature range so your plants can thrive happily.

2. Bad Soil

If growing with the soil, you must start with good high-quality soil or coco coir, eventually avoiding overwatering and underwatering.

Bad soil is usually heavy or muddy.

Plants in bad soil will suffer from various issues and eventually droop and curl their leaves downward.

Doesn’t matter how much water you put into it or how much fertilizers you feed them. If the growing medium (soil) quality is bad, you may face this issue.

Instant Solution For Bad Soil:

The best solution is to start your cultivation journey with top-quality growing medium or soil. You can find some best quality soil even in online stores.

However, if you are already in this situation, you can thoroughly drain your soil. Make your soil a little light for proper drainage and feed nutrients accordingly.

So, in a nutshell, either buy quality soil or follow the soil drain.

1. Genetics

Genetics can also be a reason for curled cannabis leaves.

You must choose a healthy parent plant if you are a professional grower who regularly breeds or reproduces cannabis plants. 

If the parent plant is healthy, then it will produce healthy and better offspring.

Otherwise, your reproduced plant will be unhealthy and weak.

And if the genetics of the plant is not good or it is not healthy, then most likely, your plant will start curling its leaves.

Instant Solution For Genetics Issue:

The best solution to avoid this issue is to find a strong parent plant if you breed cannabis plants.

But somehow, if you have a weak plant, you can use the nutrients or fertilizers to help your plant thrive in the best possible manner.

So, water your plants regularly, and give them enough fertilizers, then you can make the most out of your plants.


What does it mean when cannabis leaves curl upward?

When you observe that the edges of cannabis leaves are curling upwards, it may be caused because the light being too close. Also, it may be caused due to light stress and heat as well. Only a few strains grow at high heat.

Another reason can also be overwatering when your plant is cold and overwatered.

What does nitrogen deficiency look like in cannabis plants?

One key sign that your plant has nitrogen deficiency is its leaves turning yellow. The older and lower leaves of your cannabis plant will start turning yellow, wilt, and then drop off.

It happens because the leaves of young plants will start to steal nitrogen from these older leaves.

You need to provide nutrients to your plants simultaneously and avoid nutrient burn.

How do you fix nitrogen deficiency?

Nitrogen deficiency can easily be fixed by providing nitrogen nutrients in the soil. However, to increase nutrient levels, you must be careful that over-fertilizing can lead to nitrogen toxicity.

So, keep a balance according to your plant size and feed them nitrogen and other nutrients through the soil.

Why are my cannabis plants clawing?

There may be one or several reasons for your cannabis plants to be clawing. Some of them can be nitrogen toxicity, overwatering, and heat stress.

You need to follow the guide above to get an instant solution for all the reasons making your cannabis leaves claw.

How to avoid heat stress in cannabis plants?

If your cannabis plants are suffering from heat stress and have diagnosed it accurately, then you need to change the temperature range immediately.

The ideal temperature range for a cannabis plant is around 20 to 28 degrees Celsius; anything upwards of this will lead to heat stress. So, keep the temperature of your grow room or tent under this range.

However, if you are growing outdoors, you must follow the right light cycle.

Cannabis Leaves Curling Up: Conclusion


Curling cannabis leaves is a common issue, and one can easily diagnose and fix it with the right knowledge.

With these 11 reasons, you will most likely find the exact reason for your plant curling its leaves and provide an instant solution to fix it ASAP.

To maximize the yield of your cannabis plant, you need to take care of the issues that your plant may face and act quickly to save them and keep the highest yield.

Remember, keeping your plants healthy and providing optimal environmental conditions are keys to a successful harvest.

Christopher Andrews
I am Christopher Andrew, the owner of 420 Expert Adviser. I have been in cannabis cultivation for more than ten years, and I'm sharing my experience with you guys using this blog!

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