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Why Are My Cannabis Leaves Curling Up + How To Fix It!

Are your cannabis leaves curling up and not looking great? Unfortunately this is often a problem faced when growing cannabis. Often referred to as “The Claw” because of the bunched up look of the leaves, its a common but totally fixable issue when growing cannabis!

The unfortunate part about curling cannabis leaves is that there are actually quite a few different issues which could be causing the issue, which makes it hard to diagnose what the actual root of the issue is.

Thankfully below we’ll cover some of the most common causes of curling or clawing cannabis leaves, and what you can do to correct them!

How to Fix Curling Cannabis Leaves?:

Just like any plant, when cannabis plants are dealing with stressors that they can’t handle, they begin to hurt. With cannabis this hurt shows by when the leaves start to curl up or down.

If you notice your leaves starting to curl either up or down, then that means your plants are in trouble!

The only way to fully fix the curling leaves is to identify what the specific issue is, and then correct this issue and let your plant begin the healing process. Obviously your plant can’t talk to you, so it can be difficult to identify what the actual issue can be, but thankfully we’ve done our research and identified a few of the most common causes.

Over Watering or Under Watering Your Cannabis Plants:

One of the most common causes of cannabis leaves curling is due to over watering your plants. Over watering or under watering your plants cause many issues in growth by essentially drowning your plant and wiping away valuable nutrients from the soil, or not providing it with enough water to perform growth functions. Watering cannabis plants is all about finding the sweet spot between over and under watering.

If you notice curling or dropping leaves, this is a big indicator of over watering. If you notice wilting or the leaves looking very weak and frail, this is a big sign of under watering.

A good eye of thumb is to make sure the top layer of your soil feels dry before you water it again. I generally recommend sticking your index finger in the soil up to your first knuckle and see if you feel water. If you don’t, it’s time to water again.

Heat Stress and Cannabis Plants:

Heat stress is another issue that will undoubtedly lead to the curling of your marijuana leaves. This predominately happens when growing outdoors, but can also happen if grow lights are too close to the plants or at a too high off wattage (providing too much heat).

Furthermore, if you’re growing indoors or growing in a closet, then you definitely need some air circulation to ensure that the air is moving and cool.

Cold Stress:

Similar to heat stress, curling can also happen if the plant gets too cold. Generally cannabis is grown in pretty warm and humid environments, so only use cool temperatures if you have strains that are designed for cold weather like our New England Strains.

If your grow is too cold, I’d suggest adding additional grow lights to ensure that the plants are receiving the warmth that they need.

Soil Deficiencies:

The next most popular reasons that you might see curling is due to the nutrients in the soil. If you’re using a standard nutrient rich garden soil, then you shouldn’t have this issue, but if you do, you might need to switch brands.

Cannabis requires specific nutrients to grow efficiently in each of its life stages, and if they don’t have these nutrients then they will begin to curl and sometimes wilt.

One of the main deficiencies that causes this is magnesium deficiency.

If you begin to notice that leaves are turning yellow and drying out or becoming crunchy then my first guess would be magnesium deficiency. Take particular notice to the oldest flowers, because they will be the first affected since they’re the oldest.

Thankfully, just by testing some more nutrient rich soil, you can often times turn this around and have your cannabis react much more positively to new soil. That being said, if you switch soil make sure you’re watching it for the next few weeks because it can take a few days for you to see any benefit.

Using Grow Lights To Prevent Curl:

If you are growing your plants inside, then obviously you’ll need some sort of lighting to trigger the flowering stage and begin the growth of your cannabis. That being said, if you aren’t using the right type of grow lights then you can quite easily see your leaves start to droop and curl.

This often means that your plants aren’t getting the lighting and “sun” that they need to grow. If you’re seeing droops that usually will mean that your current grow lights aren’t strong enough and not providing enough light to your plants.

That being said, if you are seeing your plant brown or get super dry, that could mean that your grow lights are too powerful or too close to your plants which would mean they are getting burnt, often referred to as light burn.

Why Do Cannabis Leaves Curl?

So above we talked about a few reasons which can cause weed leaves to curl, but why do they physically curl?

Generally when leaves begin to curl it means that the leaf is weak and it loses its structure based on the weak cells of the leaf. For example, this happens with over watering and under watering because the leaf doesn’t have the ability to grow properly, and it causes loss of structure, which causes the leaves to fold and grow in irregular shapes.

Final Thoughts on Curling Leaves:

Curling weed leaves can be a really frustrating thing to deal with because there are so many different causes. That being said, by being informed on a few of the different causes, you should be able to identify which issue is affecting your grow. Once you’ve identified the issue, generally you still have time to turn it around and save your crops!

Why Are My Cannabis Leaves Curling Up + How To Fix It! Are your cannabis leaves curling up and not looking great? Unfortunately this is often a problem faced when growing cannabis. Often referred

Why are Leaves Curling or Clawing? (“The Claw”)

The following symptoms are for when your cannabis leaves are “clawing” or curling up or curling down. Sometimes known as “The Claw”. I’ll give a short explanation with pictures of each problem, plus links to the solutions! Fix this common (but hard to diagnose) marijuana problem today!

Nitrogen Toxicity

A Nitrogen toxicity is the result of the plant getting too much Nitrogen (usually from too high levels of nutrients overall, or by using a Vegetative nutrient in the flowering stage). It causes dark green leaves and curled tips (“the claw”).

One of the main symptoms of a Nitrogen toxicity is curled tips (“the claw”)

A plant with a Nitrogen toxicity tends to be dark green all over

Wind Burn

Caused by too much wind. You’ll notice that the leaves further from the fan don’t have symptoms.

Example of too much wind on your leaves

Bad Soil / Overwatering / Underwatering

You can help prevent over and under-watering your cannabis plants by always starting with good soil or coco coir.

Bad Soil

Bad soil is usually thick and muddy. Plants in poor soil will droop (often with unhappy curly leaves) no matter your watering practices.

Avoid thick soil that stays wet for a long time and doesn’t drain well

Overwatering

Overwatering makes leaves fat with water, and they tend to curl down and droop

Overwatering (especially when combined with heat) can also cause leaves to curl up

This plant was grown in muddy soil, and the curling, unhealthy leaves kept getting worse and worse over time!

Underwatering

Underwatering causes symptoms that often look like overwatering, but you’ll know it’s underwatering if the plants perk up each time after you water them.

Root Problems

Although often caused by overwatering, once the roots are sick you’ll see symptoms for a little while even after you start watering your plants properly.

Unhealthy roots can cause all sorts of problems including curling and clawing!

Unhealthy Roots in Soil/Coco

This plant’s roots were damaged from being overwatered and too hot for several days. As a result, the leaves took on a strange, blistery appearance.

This plant suffered from heat combined with overwatering for several days. This damaged the roots and gave it this odd leaf curling.

Root Rot

Root rot is something marijuana hydroponic growers can suffer from if pathogens attack the roots. It is often triggered by heat and/or lack of bubbles near the roots.

Root rot can cause curling leaves and brown patches as well as sometimes other nutrient deficiencies

Rootbound

If a plant stays in the same container for too long, the roots will eventually start wrapping around the edges of the pot. This is known as being “rootbound” and causes symptoms similar to other root problems.

A rootbound plant has been in the same container for too long. Roots wrap around the edges and “choke” the plant.

Rootbound plants often droop, appear yellow, get nutrient deficiencies, and stay small. Even if you’re caring for them perfectly!

If you see tons of white roots when transplanted, that means the plant was in that container too long

When this happens, the main solution is to transplant the plant into a bigger container. Another solution is to grow in fabric pots or air pots. These types of pots let air in from the sides, killing the circling roots (“air-pruning” them) and prevents the plant from getting rootbound for months.

To help a rootbound plant, transplant to a bigger container with fresh potting mix

Or start with air pots or fabric pots in order to prevent plants from getting rootbound at all

Heat Stress

If plants are experiencing a lot of heat, it can make leaves droop and/or curl. Some strains can handle a lot of heat, while other strains tend to droop when it gets warm.

Heat can cause leaves to curl up

Read more about heat and growing weed:

Light Burn

Plants can get light burn (sort of like a sunburn) even if the temperature is completely under control. The symptoms are usually concentrated close to the grow lights. Sometimes this can cause leaves to claw and curl downwards.

Light burn can cause the leaves closest to the light to turn yellow

Bugs & Pests

Often a bug infestation caused general plant unhappiness, but these are some of the most likely to cause curling or clawing leaves.

Broad Mites

Usually, you can’t see broad mites because they live inside the plant. The main symptom of an infestation is strange leaf curling that is specific to this pest, as well as “wet” looking leaves.

Hemp Russet Mites

Hemp russet mites can also cause drooping and other strange symptoms, but the bugs are so small many growers don’t realize what they’re dealing with.

Hemp russet mites cause drooping and yellow mold-like growth on the tops of plants

A closeup of the hemp russet mites

Fungus Gnats

Fungus gnats look like tiny flies buzzing around your topsoil. Although a few fungus gnats won’t really hurt your plants, a big infestation can damage the roots, causing symptoms similar to other types of root problems.

Learn about the various things that cause cannabis leaf curling or clawing, and get the solutions!