Cannabis leaves curling? Causes and solutions

Cannabis leaves curling up

Hey there, fellow cannabis grower! Welcome to our detailed guide on a common issue many of us face: Why are your cannabis leaves curling up? 

If you’ve noticed those once luscious green leaves taking on a curious curl, don’t panic just yet! We’re here to help you understand what might be causing this problem. We will guide you through the process of diagnosing and addressing it.

As a passionate cannabis grower, you know that it’s essential to keep your plants happy and healthy. Cannabis leaves curling up is often an indication that something is amiss in your grow space. Ignoring it could have detrimental effects on your precious harvest. That’s why it’s crucial to dive deep into the potential causes and solutions for this peculiar leaf curling.

Fear not, my friend! In this article, we’ll provide you with information and advice to unravel the mystery behind those curling leaves. 

We’ll explore various factors that could be contributing to this problem. These factors include nutrient deficiencies, watering issues, environmental fluctuations, pests and diseases, and even genetic factors. By understanding the root causes, you’ll be empowered to revive your plants and prevent cannabis leaf curl up in the future.

Disclaimer: Any information given on this site is for educational purposes only. Please ensure if you’re growing cannabis you’re doing so in accordance with the law and subject to appropriate permissions and licenses of the applicable country.

Understanding leaf curling

Definition and common signs of leaf curling

When we talk about cannabis leaves curling up, we’re referring to the noticeable curling or rolling up of the leaves of cannabis. Cannabis leaves should have a flat and open appearance. Plants that are suffering will exhibit twisted cannabis leaves and edges of leaves curling up.

Leaf curling is a clear visual indicator that something isn’t quite right with your cannabis plant. Take it as an early warning sign that your plant might be experiencing stress. It’s also a sign that your plant is facing an underlying issue that requires your attention.

Importance of addressing leaf curling promptly

Addressing any cannabis leaves curling up promptly is crucial. Leaf curling affects the aesthetic appeal of your plant. But it can also have a significant impact on its overall health and productivity if left untreated. 

Leaves play a vital role in photosynthesis, the process by which plants convert light into energy. Any disruption to their structure or function can hinder the plant’s growth and development.

By taking immediate action when you notice leaf curling, you can prevent the problem from escalating. Additionally, addressing the underlying issue causing the leaf curling will improve the overall well-being of your cannabis plant. This leads to healthier foliage and a higher chance of a bountiful harvest.

Benefits of diagnosing the underlying issue

Diagnosing the underlying issue causing leaf curling is like being a detective on a mission to restore your plant’s health. By identifying the root cause, you can implement targeted solutions that specifically address the problem. This will save you time, effort, and resources in the long run.

Understanding the cause of leaf curling will empower you with knowledge. You can then apply that knowledge to future grow cycles. 

You’ll become more confident at spotting early signs of stress or issues. You will also be more equipped to intervene before they escalate. This proactive approach will improve the overall health of your plants. 

Why are my cannabis leaves curling up and burning?

Nutrient burn, overwatering and pest invasions are all possible causes. Understanding these potential causes is key to pinpointing the specific issue affecting your plants. Let’s explore some of the common culprits behind leaf curling and how they manifest:

Nutrient deficiencies

Lack of Nitrogen (N): Nitrogen is an essential nutrient for cannabis growth. Its deficiency can lead to pale leaves, stunted growth, and curling downwards of older leaves.

Potassium (K) Deficiency: Insufficient potassium levels can result in yellowing edges and tips of leaves, along with curling.

Magnesium (Mg) Deficiency: Lack of magnesium often causes interveinal chlorosis (yellowing between leaf veins). It also causes leaf curling and overall poor growth.

Calcium (Ca) Deficiency: Insufficient calcium can lead to distorted leaf growth, including curling, and may result in necrosis or tissue death.

Overwatering and underwatering

Overwatering can cause roots to become waterlogged, leading to oxygen deprivation and root rot. This can result in wilting, curling and yellowing leaves.

Insufficient watering can cause plants to become dehydrated, resulting in droopy, curled leaves and dry, brittle foliage.

Finding the right balance is crucial. Ensure that you water your plants adequately, allowing the top layer of soil to dry out slightly before the next watering. Avoid overwatering to prevent waterlogged roots.

Temperature and humidity fluctuations

High temperatures and low humidity: Excessive heat combined with low humidity can cause stress to cannabis plants. This results in leaf curling as a defence mechanism.

Low temperatures and high humidity: Cold temperatures combined with high humidity can create a breeding ground for fungal diseases. This can lead to leaf curling and other symptoms.

Pest and disease infestation

Pests such as spider mites, aphids, and thrips can cause damage to leaves. This causes curling, yellowing, and the presence of webs or pests themselves.

Regularly inspect your plants for signs of pests, such as visible insects, webbing, or small holes in the leaves. Take appropriate measures to control and eliminate the infestation.

Diseases like powdery mildew or bacterial leaf spot can cause leaf curling. Other visible cannabis leaves symptoms are spots, lesions, or powdery growth on the leaves.

Genetic factors

Some cannabis strains may naturally be more prone to leaf curling due to their genetic makeup. It’s important to consider strain-specific characteristics when troubleshooting leaf curling.

When choosing strains for your grow, consider selecting those known for their resilience to common issues like leaf curling. Consulting with breeders or fellow growers can provide valuable insights.

By understanding these potential causes, you’re on your way to diagnosing and addressing the leaf curling issue in your cannabis plants. In the next section, we’ll explore effective methods for diagnosing the underlying cause with precision. Stay tuned!

Green cannabis leaves curling up

Diagnosing leaf curling

Careful observation and analysis of plant symptoms

Observation is your most valuable tool for diagnosing the underlying cause of leaf curling in your cannabis plant. Take the time to carefully examine your plants and note any accompanying symptoms. Here’s what to look for:

  • Observe the pattern of leaf curling: Note whether the curling is affecting new growth, old leaves, or both. This can provide clues about the timing and possible causes of the issue.
  • Check for discolouration: Pay attention to any changes in leaf colour, such as yellowing, browning, or spotting. Discolouration can indicate nutrient deficiencies, pest infestations, or diseases.
  • Examine leaf structure and texture: Feel the leaves to assess their texture. Are they soft and pliable or dry and brittle? Also, inspect the overall structure of the leaves for abnormalities like misshapen growth or twisting.
  • Look for other visible signs: Keep an eye out for webs, insects, spots, lesions, or powdery growth on the leaves. These can provide vital clues about pest infestations or diseases.

Using diagnostic tools and techniques

Careful observation is just one tool. There are several other diagnostic tools and techniques that can identify the cause of leaf curling. Consider the following:

pH testing: Use a pH testing kit to determine the acidity or alkalinity of your soil or growing medium. Improper pH levels can hinder nutrient absorption and contribute to leaf curling.

Nutrient deficiency testing kits: Test kits are available that allow you to assess nutrient levels in your soil or plant tissue. These kits can help pinpoint any specific nutrient deficiencies contributing to the leaf curling.

Pest identification guides: Consult resources that provide comprehensive information and images to help you identify common pests affecting cannabis plants. Compare the symptoms you observe with those depicted in the guides to narrow down the potential culprits.

Remember, accurate diagnosis is key to implementing targeted solutions. By combining a range of these tools and techniques, you’ll be well-equipped to identify the root cause of leaf curling. 

In the next section, we’ll delve into effective strategies for addressing the specific causes we’ve discussed. So, grab your notepad and get ready to tackle those curling leaves head-on!

Addressing leaf curling issues

Now that you’ve observed your cannabis plants and diagnosed the underlying cause of leaf curling, it’s time to take action. Here are some effective strategies for tackling common causes of leaf curling:

Nutrient deficiencies

If a nutrient deficiency is identified you need to amend the soil. This can be done by applying the appropriate organic or synthetic fertilisers. Follow the recommended dosage and application instructions provided by the manufacturer. Research and choose fertilisers formulated to address the specific nutrient deficiencies in your plants. 

Watering techniques

Ensure you’re providing your plants with the right amount of water. Water thoroughly, allowing excess water to drain away, and avoid letting your plants sit in standing water.

Overwatering or underwatering can contribute to leaf curling.

Pay attention to the moisture levels in the soil and the appearance of your plants. Adjust your watering routine accordingly if you notice signs of overwatering. Look out for waterlogged soil, or signs of underwatering, such as dry and wilted plants.

Maintaining ideal environmental conditions

Create a suitable environment for your cannabis plants by maintaining optimal temperature and humidity levels. Aim for temperatures between 20-26°C (68-78°F) during the day and slightly lower at night. Keep humidity around 40-60% during the vegetative stage and lower to 40-50% during the flowering stage.

Promote proper air circulation within your grow space by using fans or ensuring a gentle breeze. This helps prevent stagnant air and reduces the risk of fungal infections.

Pest and disease control

Integrated Pest Management (IPM) strategies: Implement a multi-faceted approach to pest control. Include practices such as regular inspection, physical removal of pests and the introduction of beneficial insects. Organic or chemical treatments may also need to be used. 

Organic and chemical treatments: Depending on the severity of the pest or disease infestation, you may need organic or chemical treatments. Always follow the instructions provided by the manufacturer and use these treatments responsibly.

Adjusting genetic factors

When selecting cannabis strains for future grows, seek out those known for their resilience to leaf curling or other common issues. Research strain reviews and consult with experienced breeders or growers for recommendations.

By implementing these strategies, you’ll be actively addressing the specific causes of leaf curling in your cannabis plants. Remember, it’s a journey of trial and error, and each grow is an opportunity to learn and refine your cultivation techniques.

In the next section, we’ll discuss preventive measures you can take to minimise the risk of leaf curling in future grows. So, let’s keep up the momentum and ensure your cannabis plants flourish without those pesky curled leaves!

Preventing leaf curling in the future

Prevention is the key to maintaining healthy and thriving cannabis plants. By implementing proactive measures and staying vigilant, you can minimise the risk of leaf curling in future grows. Here are some preventive steps to consider:

Regular plant care and maintenance

  • Proper nutrition: Ensure your plants receive a balanced diet by providing them with appropriate nutrients throughout their growth stages. Follow a feeding schedule and monitor nutrient levels to prevent deficiencies or excesses.
  • Pruning and training: Regularly prune your plants to remove any dead or damaged leaves. This will improve airflow and reduce the risk of diseases. Consider training techniques such as topping or LST (low-stress training) to promote even growth and prevent overcrowding.
  • Sanitation practices: Maintain a clean growing environment by regularly sanitising your tools, pots, and grow area. This helps prevent the spread of pests and diseases that can contribute to leaf curling.

Monitoring plant health and environmental conditions

Routinely inspect your plants for any signs of stress, pests, or diseases. Catching issues early allows for swift intervention and minimises the chances of leaf curling.

Continuously monitor temperature, humidity, and airflow within your grow space. Invest in environmental control devices, such as thermometers, hygrometers, and fans, to maintain optimal conditions for your plants’ growth.

Introducing the Grow Sensor: Optimising your indoor growing efforts

The Grow Sensor is a cutting-edge grow room sensor. It has been specially crafted to cater to your needs as an indoor, greenhouse, or tunnel grower.

This smart sensor combines various atmospheric sensors with a soil probe that measures temperature, moisture, and EC.

Let’s delve into its standout features:

  • Real-time Monitoring: With the Grow Sensor, you gain the ability to effortlessly monitor your grow spaces. You’ll receive valuable insights about your growing environment and soil data anytime and from anywhere.
  • Enhanced Quality and Consistency: By leveraging the provided information, you can make informed decisions. This will enhance the quality, quantity, and consistency of your cultivated end products.
  • Microclimate Management: The Grow Sensor helps you identify and effectively manage microclimates. This minimises nutrient waste and pest-related issues along the way.
  • Informed Decision Making: The Grow Sensor delivers actionable insights that inform your decision-making. These insights are accessible through desktop and mobile applications available on Apple and Android devices. This, in turn, enables you to cut costs, maximise return on investment, and drive profitability.
  • Unbeatable Accuracy and Connectivity: Designed with innovation and reliability in mind, the Grow Sensor boasts top-notch hardware. It also features precision wireless sensor equipment. It ensures swift installation, robust connectivity, and unmatched accuracy, guaranteeing you optimal results.

With the Grow Sensor at your disposal, you can revolutionise your cultivation processes, efficiency and success in your indoor growing.

Implementing preventive measures

Set up a comprehensive IPM plan to prevent and manage pests effectively. This includes practices like maintaining cleanliness, using natural predators or repellents and employing preventive treatments.

Apply organic foliar sprays, such as neem oil or insecticidal soap, as a preventive measure against common pests. Follow the recommended application guidelines and avoid spraying during flowering to prevent unwanted residues.

Regularly updating your knowledge of cultivation techniques and strains

Continuously educate yourself about the latest cultivation techniques, pest control methods, and advancements in cannabis genetics. Engage in online forums, join grower communities, and read reputable cannabis publications to expand your knowledge.

Connect with other growers, breeders, and experts to share experiences and learn from their insights. Participate in workshops, seminars, or local grower meet-ups to gain practical knowledge and stay up to date with industry trends.

By implementing these preventive measures, you’ll create a solid foundation for successful cannabis cultivation. Remember, prevention is always better than cure. Taking proactive steps will help you avoid the frustration of dealing with leaf curling in the future.


Congratulations! You’ve made it through this comprehensive guide on why cannabis leaves curl up and how to address this issue. We hope that you are now equipped with the knowledge and strategies needed. You should now feel ready to diagnose, treat, and prevent leaf curling in your cannabis garden.

Remember, as a passionate grower, your journey is a continuous learning experience. Each plant teaches us something new. With time, patience, and dedication, you’ll become even more skilled at nurturing healthy and thriving cannabis plants.

So, keep your enthusiasm high and embrace the challenges along the way. Armed with your newfound knowledge, you’re ready to tackle any leaf curling issue that comes your way. Happy growing, my friend, and may your future harvests be abundant and leaf-curl-free!

Author avatar
Tom Starley
Founder at - the smart agri-sensor. Chilli grower extraordinaire. Passionate about growing food sustainably. Keen mushroom hunter and tech advocate. Tom is currently open for Guest posts.

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