What causes cannabis leaves to curl up? – Hon&Guan

What causes cannabis leaves to curl up?

Cannabis growers do not want to see canoeing or curling in their cannabis leaves. While there are many possible causes for this issue, the fact that cannabis plants themselves contain over 90% water is usually indicative. 

Why are my cannabis leaves curling? has a number of more possible responses. "Keep reading to learn how to diagnose your plant's condition correctly and treat it swiftly. Curly cannabis leaves could be present in your grow operation for a variety of reasons. This article will discuss the causes of this phenomenon and what you can do to stop it from degrading your finished work.

Examples of Leaf Curling and Their Causes



The most prevalent cause of bent cannabis leaves is overwatering. Watering is necessary for the marijuana plant's existence, but too much watering might suffocate the roots and ruin your cultivation efforts. Cannabis leaves that are twisted quickly droop. If growers don't deal with the underlying issue, it will only get worse.

Being soaked could cause roots to suffocate because they need oxygen to survive. Through their roots, healthy plants absorb nutrients from the water. Plants start to wilt and weed leaves curl up because too-much moisture in the soil prevents this process from taking place.

Growers with little experience should water their plants sparingly rather than excessively. Particularly seedlings need only a small amount of water. One piece of advice is to weigh your containers both dry and after being newly watered, and then add more water just when it feels necessary.

If you think this is too hazardous, buying a soil moisture meter can be a good idea. Just insert the tip into the soil to measure the moisture content. Although many highly skilled cannabis producers frequently believe they have the knowledge to know how much water to add at each stage of plant growth without moisture meters, this removes a lot of the guesswork.

Pythium, often known as root rot, is a parasite problem that can cause persistent overwatering and transform your roots into a filthy, unproductive sludge.  Your plants may succumb to a variety of microscopic diseases, including fungal and algae.

Nutritional Inequality:

Nutritional Inequality

An unbalanced diet is another typical cause of twisted cannabis leaves. Different nutrients have different effects on plants, and excesses or deficiencies of a particular nutrient can result in a variety of problems. N, P, and K are the three main macronutrients required for the growth of cannabis. You can notice curling or canoeing in your cannabis leaves if they are out of proportion. For instance, a lack of nitrogen can cause lower leaves to curl, become brown, and eventually fall off.

However, too much nitrogen can cause stunted development as well as twisted and clawed leaves. Similar to how too much phosphorus can generate stiff, curled leaves, not enough phosphorus can result in yellowing, curly, or even purple stems. Using a high-quality, balanced nutrition solution is the best strategy to prevent nutrient imbalances. Additionally, you can improve your soil by adding organic fertilizers or additives like kelp meal, worm castings, or bat guano. Just remember to adhere to suggested application rates and steer clear of overfertilizing, which can also result in nutrient imbalances.

Environmental elements:

Cannabis leaves that are curled can also be caused by other environmental variables. For instance, the leaves may curl up to conserve water and stop transpiration if your grow space is too hot. Similar to how your cannabis leaves may curl down to retain moisture if your grow room is too wet. Leaf curling can also be brought on by too much light, particularly if your plants are too close to the grow lights. To avoid harming your plants in this situation, you might need to lower the wattage of your lights or change their height. Curled cannabis leaves can also be brought on by diseases like powdery mildew or bud rot, as well as parasites like spider mites, thrips, and aphids. These problems can be avoided from becoming serious problems with routine inspection and treatment. In conclusion, there are a variety of reasons why cannabis leaves curl, and it's critical to identify the underlying problem in order to stop additional harm to your plants. You can encourage your cannabis to flourish and yield a plentiful crop by keeping an eye on watering, nutrient balance, and environmental conditions.

Excessive fertilization:

Excessive fertilization

Weed leaves are sensitive, especially when they have been exposed to excessive fertilizer. During the vegetative stage, excessive nitrogen use can result in leaf problems such curled leaves, burns, and dark green coloring. The same is true for the flowering phase, when too much phosphate or potassium causes the leaves of cannabis plants to twist.

Most regular growers will already be familiar with nutrient burn. At this stage, the tips of the cannabis leaves are scorched brown, which resembles the signs of heat exhaustion. For many gardeners, it can be difficult to find and maintain the nutritional sweet spot for plants from seedling to harvest. In reality, expert growers usually invest a lot of time and energy into honing their skills in precise fertilizer delivery. Growers are encouraged to start with poor nutrients and gradually/slowly build them up as their plants mature, especially those with less experience. To reduce mineral concentrations at the root level, consider a water flush as soon as there is even the slightest indication of overfeeding.

Too warm:

Cannabis is a marijuana that grows readily in many climes, however most strains are incompatible with temperatures exceeding 860°F. They'll let you know with curled weed leaves if you combine severe heat with low relative humidity.

Over 860F temperatures prevent leaves from photosynthesizing, causing them to curl, canoe, and droop. Cannabis leaves may also go yellow, drop off, or become brittle and brown. Because of the extreme heat, new growth frequently becomes distorted. Both indoor and outdoor heat stress are possible. When temperatures rise too high, cannabis leaf edges may wrinkle, become dry/crisp, and curl. In hot weather, the leaf cells lose water more quickly than they can replenish it, which causes peculiar leaf curling. By adding more extraction or, if accessible, air conditioning, lower the temperature in your grow space.

Additionally, you could wish to increase the grow light's height, which could lower canopy temps (particularly when HPS lights are being used). If ambient conditions are simply intolerable, some producers grudgingly refrain from planting during the hottest seasons of the year.

Warmth Stress:

Heat stress is among the most frequent causes of cannabis leaves curling. Cannabis plants will begin to curl their leaves when they are subjected to high temperatures for an extended length of time in order to lessen the amount of surface area that is exposed to the heat. Other signs like wilting and leaf browning or yellowing are frequently present along with this.

Keep your grow space or outdoor grow area at the ideal temperature range for cannabis plants, which is between 68-78°F (20-26°C), to prevent heat stress. To lower the temperature, you can also utilize a variety of cooling methods including air conditioning, fans, or shade cloth.

Lack of Certain Nutrients:

Nutrient deficits are another major cause of cannabis leaves curling up. Your plants' leaves may begin to curl and develop yellow or brown spots if they do not receive enough of the vital nutrients they require. Nitrogen, phosphorus, and potassium deficiency are some of the most typical nutrient deficits that can result in leaf curling.

Make sure your plants are receiving the proper nutrients at the appropriate times in order to avoid nutrient deficits. This can be accomplished by routinely fertilizing your plants with a balanced nutrient mix and high-quality soil or hydroponic systems.

Cannabis plants thrive in a pH range of 6.0-7.0 for soil and 5.5-6.5 for hydroponics, therefore it's also crucial to keep an eye on the pH levels of your growth media. Your plants may be unable to absorb the nutrients they require if your pH levels are outside of this range, which could result in deficiencies and curled leaves. It's important to remember that excess nutrients, especially nitrogen overload, can also result in curled leaves.

Nutrient burn, when the leaf tips turn brown and crispy and the leaves may curl up, can be caused by overfeeding your plants with nutrients. Avoid overfeeding your plants by adhering to the advised nutrient feeding schedule.

Diseases and Pests:

Diseases and Pests

Another frequent reason for curling cannabis leaves is pests and illnesses. Common pests like thrips, aphids, and spider mites can do serious damage to your cannabis plants. Your plants' leaves may twist and droop as a result of these small insects sucking the sap out of them. They can also spread viruses and other infections, so it's critical to find and address the issue very away.

Another prevalent condition that can cause cannabis leaves to curl up is powdery mildew. The leaves and stems of plants with this fungus illness develop a powdery white substance as a symptom. Powdery mildew can spread quickly and significantly reduce yield if neglected.

Botrytis, another name for the fungus that causes bud rot, is a condition that affects the buds of cannabis plants. The leaves and buds may curl and turn brown from this condition, which often occurs in moist, humid environments. It's critical to identify bud rot early and take precautions to avoid it since if left untreated, it can completely damage crops.

Another possible reason for curling cannabis leaves is root rot. When a plant's roots are continuously exposed to moisture and aren't provided with enough oxygen to grow, this situation develops. The roots will start to rot over time, which will cause a variety of issues, such as curled leaves. Make sure your plants aren't overwatered, and check that your growth pots have enough drainage to prevent root rot.

Too chilly:

Around 500F is at the other end of the range where cannabis can grow successfully. The issue is prolonged periods of lower temperatures, not brief spurts. Curled cannabis plant leaves are the first indication that your crop isn't loving its chilly surroundings.

The growth of your plant could be permanently stunted if temperatures don't rise, and they might not even reach the flowering stage. If they do, the yields will be poor and the buds will be loose or leafy and not fully developed.

To produce stunning purple or blue colorations, many growers use colder temperatures late in the blooming process. However, these are just drops during the night (or dark phase). Long-term exposure to low temperatures will first cause marijuana leaves to curl and will ultimately cause the plants to die. Your plant's biochemistry and photosynthesis are considerably slowed down in cold weather. This could result in a plant with leaves that slightly curl downward.

Little can be done for growers who are outside. But to for plant growth to return to normal, indoor growers only need to raise the temperature of their grow space.

Investing in a cheap minimum/maximum thermometer to track the temps in your grow room is a wise move for any producer. This demonstrates the temperature range in which your plants thrive and could assist you in maintaining a grow environment that is more ideal.

One may want to elevate their plant pots over the potentially chilly stone or concrete surface if they are growing their plants, for example, in a cool cellar. The plant pots might also be placed on a tiny stand to avoid the root zone from becoming overly cold, which would impede growth and diminish final yield and potency.


Cannabis leaves that curl are largely the result of genetic factors. Some strains have been cultivated to have particular characteristics that increase their propensity to have curly leaves. For instance, it is well known that the genetics of sativas and autoflowers predispose them to growing curly leaves.

Cannabis leaves may also curl as a result of genetic abnormalities. While it is possible for these mutations to arise naturally, they can also be brought about by breeding strategies like crossbreeding and hybridization.

Cannabis leaves that curl can be caused by genetics, genetic mutations, and an abundance of nutrients. To guarantee healthy and growing cannabis plants, growers should be aware of these potential causes and take the necessary steps to prevent or treat them.

How Can Curling Cannabis Leaves Be Fixed?

Less experienced producers frequently, but not always, notice curled cannabis leaves. This might be the case since less experienced growers have a tendency to err more on the side of overfeeding and overwatering than do those who have developed better grow abilities.

It becomes simpler for the grower to determine whether the grow container needs more water once they have experienced a few successful growths. If in doubt, using a cheap soil moisture meter can give you the peace of mind you need to stop overwatering.

A moisture meter can help less experienced growers keep their plants from resting in soggy soil and being permanently stunted.

Maintaining your cannabis plants at the nutrient sweet spot may seem as challenging, but novice growers can sidestep the challenges posed by the production and distribution of mineral nutrients by using slow-release organic fertilizers like BioTabs. Using these, you might not need to provide anything at all during late bloom, possibly just a light top dressing of all-purpose bloom nutrition.

Maintaining a healthy growth environment is essential to preventing and treating curling cannabis leaves. Maintain temperatures between 65- and 85-degrees Fahrenheit (18 and 29 degrees Celsius), and make sure your plants have adequate air movement and ventilation. Leaf curl can also be caused by high humidity, so if necessary, purchase a dehumidifier.

Additionally, make sure you are using the right nutrients and watering techniques for your plants. Leaf curl can result from excessive or insufficient fertilization or irrigation. It's crucial to strike a balance and adhere to the right eating schedule.

If pests or diseases are to blame, it's critical to spot and address them right away. Depending on the seriousness of the problem, employing pesticides and fungicides that are chemical or organic may be necessary. The development of diseases and pests can also be halted by maintaining a clean growing environment and maintaining proper hygiene.

Last Words & Suggestions:

Cannabis plants can tell you a lot about their health from their leaves because they are highly sensitive to a variety of environmental conditions. Cannabis leaves curling up is one difficulty that many producers frequently run across. Numerous things, including as heat stress, nutrient deficits, pests, and illnesses, might contribute to this.

Curled cannabis leaves are a typical problem, but you should deal with them right once to protect your plants from further harm. You can keep your cannabis plants healthy and thriving by maintaining a clean growing environment, giving them the right nutrients and water, and taking care of any pests or diseases as soon as they appear.

Additionally, regular plant monitoring and attentive observation of any changes in leaf appearance can assist identify problems early on before they worsen. Cannabis cultivation can be gratifying, but it demands close attention to detail and a willingness to learn about and adjust to your plants' needs. Leaf curling can be avoided with time and effort, allowing for a successful harvest.

In conclusion, a variety of environmental conditions, including as heat stress, nutrient deficits, pests, and diseases, can contribute to cannabis leaves curling up. Understanding the root reasons of leaf curling and taking the necessary action to solve them will assist to ensure that your cannabis plants develop into robust, healthy plants that provide large quantities of high-quality buds.



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