The Causes of Cannabis Leaves Curling Down and How to Remedy Them

One of the major problems that most people experience with marijuana plants is clawing or curling of the leaves. Although the curling down of cannabis leaves is a common phenomenon, it is usually difficult to diagnose, especially for new growers. When you are a knowledgeable grower, you can correctly diagnose the cause of your cannabis leaves curling and rectify the problem.

Growing cannabis may seem quite easy, however, just like other plants, issues may arise that can hinder its growth. As your cannabis plants start growing and developing, they will also have leaves and grow in stature. However, when leaves start curling down or up, then it is a sign that something is wrong with your marijuana plants. Whether you are a beginner or an expert grower, you need to diagnose the problem causing your marijuana leaves to curl and fix the issue.

cannabis leaves curling down

Cannabis plants usually send signals to show you that all is not well. If you notice the leaves curling down or clawing, then there is a problem with your plants. Curling down of cannabis leaves is mainly caused by nitrogen toxicity, overwatering, bad soil, extreme temperatures, genetics, and windburn. In this guide, we will look at these causes and remedies for curly marijuana leaves to ensure your plants grow healthy and produce a high yield.

What is “clawing”?

Clawing simply refers to the curling up and down of cannabis leaves. This occurrence is also known as “the claw”. Clawing can be caused by different factors and when it occurs, your marijuana plants require special attention. If the plants are not cured, their growth will be hindered or they may die.

What Are The Causes Of Marijuana Leaves Clawing And How Can This Problem Be Fixed?

Curling is a signal or sign that your marijuana plant is sick and requires treatment. Curling or clawing of marijuana leaves may be an indication of a problem. There are several causes of marijuana leaves curling up and down. However, this should not be a cause for alarm because there are many ways of curing your plants. Some of the causes of curling leaves include the following:

Overfertilization of Cannabis Plants

Cannabis leaves curling down

Overfertilization of your cannabis plants is not good. This is because using excess concentration of a nitrogen-rich growth base can cause the curling down of leaves. Overdoing any mineral-rich or vitamin-rich feeding can also cause the plants to curl and the tips of the leaves will also scorch.

To cure excessive fertilization of your plants, you need to regulate whatever you are giving to the plants. Ensure that you keep a feeding chart to keep track of every nutrient or vitamins that your plants are getting. Ensure that you go slow and low when using fertilizers on your cannabis plants and increase the dosage with time.

Always check the cannabis leaves each day to determine how the plants are responding to your feeding process. Growers must also ensure that whatever fertilizer you are feeding your plants has the right nutrient solution and pH. The best pH is approximately 5.8 to 6.0pH.

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Overwatering Marijuana Plants

Most growers believe that watering their cannabis plants helps to keep them healthy at all times. However, this is not true. Overwatering your plants can be dangerous because it downs the roots of the plant. In addition, it eliminates helpful microbes that your plant needs. Additionally, excessive watering attracts Pythium, which are parasites that cause rotting of the roots. All these will cause your cannabis plants to have curled down leaves, a sign that the plants are waterlogged.


To cure overwatering, you need to reduce the volume of water you give the plants, by maintaining a wet-dry cycle. You can always determine whether your plants need watering or not based on their weight. You can also check whether your marijuana plants need water or not by pressing the soil to determine whether it is too moist or dry. If the soil is too moist, then you can postpone watering until the next day, but if it is dry then give them just the right amount of water.

Extremely Hot Temperatures


Heat stress is dangerous to your marijuana plants and can occur both in outdoor and indoor cultivation. When temperatures are extremely high, your leaves may curl and have brown tips. These are signs that your plants are suffering from heatstroke and is a distress call that you have to take note of. The best temperature for growing your cannabis plants should not exceed 28 degrees Celsius, because any readings above this will affect your plants and even burn the leaves.

Regulating the grow room temperature can help to cure this problem. Adjusting and lowering the temperatures for indoor growers is quite easy and you can use an air conditioner to lower the temperatures. For outdoor growers, regulating temperature or exposure to heat can be quite a challenge. However, most growers utilize a screen that provides shade and keeps cannabis plants slightly cooler.

Extremely Cold Temperature

Very cold temperatures may also affect your cannabis plants. Cold temperatures also cause the leaves to curl down as well. Exposing your plants to cold temperatures of over 10 degrees for a long time will not only cause curly leaves but can also kill your marijuana plants. The buds will also become moist and can get sick if the problem is not remedied immediately.

To solve this problem, you can increase the temperatures for your indoor cultivation by adding more grow lights. Controlling the temperatures outdoors can be difficult and the best way to deal with this problem is harvesting your buds early. The optimum temperature for the healthy growth of marijuana plants is 20 to 28 degrees Celsius.

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If you plan to breed or reproduce your cannabis plants, you must ensure that the parent plants are healthy. Based on genetics, healthy parent plants will produce healthy progenies. Unhealthy parent plants usually pass on diseases to their offspring and this will cause them to also grow up unhealthy. Genetics may also be a reason why your marijuana leaves are clawing or curling down.  To fix this problem, you will have to feed your marijuana plants with the fertilizer or nutrients they need to heal them from any type of sickness.

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Other Causes of Cannabis Leaves Curling Down

Bad Soil


Another major reason that can cause cannabis leaves to curl is bad soil. If the soil you are using is bad or you are growing plants in muddy and thick soil, the leaves will curl and droop regardless of your watering practices. Growers need to use the right type of soil that can support the healthy growth of marijuana plants if they desire a bounty harvest.

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Another problem that can cause marijuana leaves to curl down is windburn and occurs when plants are getting excessive wind. If you are cultivating your marijuana indoors, you will notice that plants that are far from the fan will not have curled leaves. This problem can be remedied by regulating the fan to prevent excessive wind from damaging your plants.


Underwatering your cannabis plants can also cause symptoms that are almost similar to those of overwatering. However, with underwatered plants, the leaves tend to perk up every time they are watered. Cannabis growers can prevent underwatering, by ensuring that their plants get adequate water.

Root Problems

Root problems in cannabis plants usually occur because of overwatering. Once your roots become sick, the symptoms usually persist for some time even after you start watering your cannabis plants properly. Unhealthy roots can trigger different issues including the curling of leaves.

If the roots of your marijuana plants are damaged, the leaves will start curling and will have an outlandish blistery appearance.  This can be caused by root damage, watering, or heat stress. Ultimately, damaged roots will result in the curling of cannabis leaves.

Root Rot

Another common cause of marijuana leaves curling down or up is root rot. This problem mainly affects cannabis hydroponic growers. Rooting of roots can be caused by heat or lack of bubbles in the cannabis roots. There will also be brown patches on the cannabis a symptom of deficiency in the roots.

Light Burn

Another major cause of curled down leaves in marijuana plants is light burn. Your leaves can still experience light burn even when the temperatures are under control. This mainly happens when growing cannabis indoors and the plants are extremely close to the grow lights. Eventually, the cannabis leaves closest to the grow lights will turn yellow.


Growing marijuana plants can be quite enjoyable and easy, however, maintaining good health requires lots of attention. The quality and quantity of your yield largely depend on the health status of the plant. If you notice your plants having curly leaves, then it means that the plants are in distress. Although curled leaves in cannabis plants is not a good sign, every grower should expect and even be prepared for these issues to occur.

As a marijuana grower, you need to act quickly and offer the most appropriate and effective solution for your plants. Although most of these symptoms can be cured, you should never disregard leaves that are curled up or down. You need to do something to fix the problem right away to save your cannabis garden and ensure you reap premium quality and bounty yields. Cannabis growers can completely avoid curly leaves if they know how to keep their plants healthy and strong.

Read next: Why Cannabis Leaves Turning Yellow

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Bowden draws from over a decade of home growing experience as well as consulting for small-scale and hobbyist-level growers. He has written hundreds of articles, thought pieces, and tutorials about growing cannabis at home

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