Why cannabis leaves turning yellow?

For every gardener, watching their plants thrive is a joy. But when cannabis leaves turn yellow, it asks, “What’s going wrong?” Let’s explore the causes behind this phenomenon and how to counteract them.

cannabis plants leaves are yellowing

Causes cannabis leaves turning yellow

Whether it’s due to nutritional imbalances, lighting issues, or external environmental stressors, understanding the root causes of these yellow leaves is paramount. The following breakdown sheds light on the many reasons behind this phenomenon and provides insights into the health of your cannabis garden.

Nutritional necessities

Much like humans, plants need various essential nutrients to grow robustly. A deficiency or even an overdose of these nutrients can adversely affect their health. When cannabis plants lack essential nutrients, especially nitrogen, they signal their distress by turning their leaves yellow. On the flip side, an overabundance of nutrients can cause nutrient burn, which can also manifest as yellowing leaves.

The watering conundrum

Finding the right watering balance can be surprisingly tricky. Overwatering drowns the roots, depriving them of oxygen leading to root rot. As the roots decay, they can no longer absorb nutrients efficiently. On the other hand, underwatering stresses the plant, making it hard for the roots to absorb nutrients from the dry soil. Both conditions can lead to yellowing of leaves, albeit for different reasons.

Balancing pH levels

The soil’s pH level is pivotal to a plant’s health. A pH level that’s too high or too low can hinder the plant’s ability to take in nutrients, no matter how nutrient-rich the soil might be. This imbalance can lead to a phenomenon known as nutrient lockout, where the plant is surrounded by nutrients but can’t use them.

Drainage dilemmas

Good drainage is paramount for plant health. Stagnant water in pots can cause the roots to become waterlogged. Plants are unable to breathe in such conditions, leading to root decay. The initial signs of this problem are often yellow, wilting leaves.

Unwanted guests – pests and diseases

Some pests, like spider mites, suck out the cellular content from leaves, causing them to turn yellow. Meanwhile, diseases like fusarium target the vascular system of the plant, blocking nutrient and water transport. Both pests and diseases can wreak havoc if not identified and treated early on.

Lighting levels

Cannabis plants, whether grown indoors or outdoors, have specific light requirements. When exposed to excessive light or very intense light for prolonged periods, they can develop a condition similar to a human sunburn. This ‘light burn’ often results in yellowing or browning at the tips of the leaves.

Genetics and plant varieties

Different strains of cannabis have varied responses to environmental factors. Some strains might be more resilient to certain stresses than others, while some might be particularly sensitive. Understanding the genetic makeup of your plant can provide insights into its specific needs and potential challenges.

Soil quality and composition

The soil isn’t just a medium for the plant to anchor its roots; it’s a dynamic ecosystem. A well-composed soil will have a mix of beneficial microorganisms that aid in nutrient breakdown and uptake. Conversely, poor soil quality can hinder growth and lead to yellow leaves.

Age and lifecycle considerations

As cannabis plants age, it’s natural for some of the lower leaves to turn yellow and drop off, especially during the flowering phase. This is a natural part of the plant’s lifecycle. Differentiating between natural aging and problematic yellowing is crucial.

Environmental stressors

Factors like sudden changes in temperature, exposure to harsh weather conditions, or even transplant shock can stress the plant, leading to yellowing. While some are unavoidable, being aware of potential environmental changes and preparing in advance can mitigate their impact.

yellow cannabis leaves

Solutions: Restoring your cannabis garden

While spotting yellow leaves might be discouraging, it’s worth noting that these symptoms often have clear solutions. By addressing the root causes, you can restore the vitality and vigor of your green companions.

The following list of remedies offers practical solutions to tackle these issues, ensuring a thriving, verdant cannabis garden. Whether it’s adopting a consistent watering routine, understanding the importance of pH balance, or harnessing the power of modern technology, the tools to turn those yellow leaves green are at your fingertips.

Balanced nutrition

Regularly monitoring and adjusting the nutrient mix can mitigate deficiencies and excesses. Depending on the plant’s growth stage and observed symptoms, one might need to increase or decrease certain nutrients.

Watering wisdom

Observation is key. The topsoil can offer insights into when the plant needs water. If the top inch feels dry, it’s watering time. Maintaining a diary can be beneficial for those unsure about their watering routine.

Maintaining pH

Regularly testing and adjusting the soil or water’s pH in hydroponic systems ensures a conducive environment for nutrient absorption. Kits available at garden centers can help with this.

Drainage solutions

Ensuring pots have adequate drainage holes is the first step. For added insurance, consider adding perlite or vermiculite to the soil mix to improve drainage capabilities.

Pest and disease management

Routine inspections can help detect and combat pests and diseases early. Organic insecticides and natural predators, such as ladybugs or lacewings, can prove invaluable in maintaining a healthy garden.

Right light regimen

For indoor growth, understanding the light needs of the specific cannabis strain and adjusting the distance and intensity of the lights can prevent light burn. Outdoor plants might benefit from shade during the intense midday sun.

Monitoring tools and technology

With advancements in gardening technology, there are now tools available that can monitor the health and needs of plants in real time. From moisture meters to smart pots that alert you when watering is needed, leveraging technology can aid even the most novice gardener in preventing yellowing leaves.

yellow cannabis plant


Understanding the intricacies of plant health can seem daunting, but with knowledge and observation, one can quickly diagnose issues. Yellow leaves, while a cause for concern, are a plant’s way of communicating its needs. Addressing these causes will restore the plant’s green vibrancy and enhance its health.


Can yellow leaves turn green again?

Some yellow leaves can recover and turn green when the underlying issue is addressed early. However, severely yellowed or damaged leaves might not regain their green color.

Fixed nutrients, but leaves still yellow. Other causes?

There could be multiple factors like improper lighting, pests, pH imbalances, or other environmental stressors. It’s crucial to conduct a comprehensive check to identify the root cause.

I moved my plant, and it’s yellowing. Is relocation the cause?

Yes, relocating can cause yellowing due to transplant shock. Plants need time to adjust to new environments, especially if light, temperature, or humidity change significantly.

Can smart pots help in preventing yellowing leaves?

Yes, smart or fabric pots offer excellent drainage and prevent root circling. This promotes healthier roots, leading to better nutrient uptake and less chance of issues like overwatering, which can cause yellow leaves.

My cannabis plant’s leaves are yellowing from the bottom up.

It can be. As cannabis plants mature, especially during the flowering phase, it’s common for older, lower leaves to turn yellow and drop off. If the yellowing is widespread or occurs rapidly, it may indicate a more significant issue.

Yellow leaves with brown spots on my plant. Why?

Brown spots combined with yellowing might indicate fungal infections or pest attacks. It’s essential to diagnose the specific cause to treat it effectively.

Alex Ramsey

Alex Ramsey

Cannabis Industry Copywriting Specialist

He combines a deep understanding of cannabis with a passion for crafting engaging content. With a focus on demystifying cannabis through education, Alex contributes to the industry’s growth with content that sells, educates, and engages the community.

Learn more about 420 Ergonomics, our team.

Latest at the Weed Blog

Animals And Marijuana Plants

Animals And Marijuana Plants

Imagine a world where the lines between the animal kingdom and the botanical realm blur amusingly, especially when it involves the green and leafy cannabis plants. This collection of images takes you on a whimsical journey, showcasing a variety of animals in...

read more
Overcoming Slow Growth in Cannabis: Action Steps

Overcoming Slow Growth in Cannabis: Action Steps

In cannabis cultivation, few things are as frustrating as expecting your plants to thrive only to find them growing at a snail's pace. Understanding the reasons behind this slow growth is the first step in addressing the issue and ensuring your plants reach their full...

read more
How to Use SM-90 for Cannabis Growing

How to Use SM-90 for Cannabis Growing

Navigating the complexities of cannabis cultivation requires not just a passion but also a deep understanding of the tools and products that can enhance plant health and yield. Among these, the SM-90 stands out as a product revered for its versatility and...

read more
Using C02 with Led Lights

Using C02 with Led Lights

In the quest for lush, potent cannabis crops, growers are turning to advanced techniques that promise to unlock the full potential of their plants. Among these, using CO2 with LED lights offers enhanced growth rates, yields, and quality. Let us delve into this...

read more