Why are my cannabis leaves curling downwards?

Adam Parsons

Cannabis Journalist & Staff Writer at Zamnesia

Adam Parsons

Last updated: 4 December 2025

Notice your cannabis leaves curling down like claws? It could be a sign of trouble, but don't panic! This common issue, often described as “clawing”, is something nearly every grower faces at some point. Whether you're nurturing your very first plant or have a few successful harvests under your belt, seeing your leaves curling downwards can be a worrying sight.

The good news? It's usually fixable. Downward curling in cannabis leaves is your plant's way of sending an SOS: a signal that something in its environment, feeding routine, or root zone needs attention. From overwatering and excess nutrients to heat stress or compacted soil, several factors can trigger those telltale drooping, claw-like tips.

In this guide, we'll help you diagnose exactly why your cannabis leaves are curling down. You'll learn to spot visual cues, use a quick symptom checklist to narrow down the cause, and apply simple fixes that help your plants recover quickly. Along the way, we'll link to in-depth Zamnesia resources, so you can explore each issue in more detail and grow with confidence.

Let's take a closer look at what's really behind those curling leaves and how you can get your plants thriving and fighting fit again.

What downward curling looks like

It’s usually easy to spot when cannabis leaves begin curling downwards. Instead of staying flat and perky, the leaves begin to droop or form a claw shape, where the tips bend sharply toward the soil. Growers often describe this as “weed leaves clawing down” or “leaves canoeing down.”

The most common visual cues include:

• Dark green leaves: A sign your plant may be receiving too much nitrogen or struggling to breathe due to overwatering.
• Firm or stiff texture: Instead of feeling soft and supple, the leaves can feel tough or brittle.
• Downward-pointing tips: The “claw” look, where the tip curls under but the rest of the leaf stays relatively flat.
• Drooping appearance: Especially noticeable during flowering or after feeding.

This type of leaf curl usually appears first on the upper or middle parts of the plant, where light and nutrient exposure are highest. While it may seem serious, it's actually one of your plant's best warning signs; a visual indicator that something in its environment or feeding cycle needs adjustment.

Before making any changes, take a moment to observe when and where the curling appears. Are only a few leaves impacted, or is it spreading throughout the canopy? Does it occur mainly during light-on periods or persist around the clock? These details will help you pinpoint whether the issue is caused by overwatering, nutrient buildup, heat stress, or root problems.

Quick symptom checklist

Before diving into complex fixes, it's worth starting with this quick reference self-check overview.

These simple observations can help you figure out why your cannabis leaves are turning down and point you toward the right solution fast.

Overwatered?

Is your soil constantly damp or heavy? Overwatering is the most common reason for downward-turned leaves. The roots struggle to obtain oxygen, resulting in drooping, soft, and claw-like leaves.

Nutrient burn?

Do you see yellow or burnt tips on otherwise dark green leaves? That's a classic sign of nutrient toxicity, especially too much nitrogen, which causes cannabis leaves to turn a deep green, almost glossy tone.

Heat stress?

Are your plants curling after prolonged exposure to light or sitting too close to powerful grow lamps? Excess heat causes leaves to curl down and edges to crisp up as the plant tries to conserve moisture.

Root issues?

Do your plants droop, grow slowly, or show yellowing even with proper watering? Root problems, such as rot or compaction, can prevent nutrient uptake, resulting in leaves curling downward during flowering or throughout the entire grow cycle.

Once you've identified which scenario sounds most like yours, move on to the next section to learn how to properly diagnose and fix each case in detail.

Common causes and how to identify them

As soon as you spot drooping leaves, your first thought might be, “What did I do wrong?” However, don't worry; the truth is that most causes are common and straightforward to identify once you know what to look for. From watering habits to nutrient balance and temperature control, each factor leaves its own visual clues.

Below, you'll find the most common reasons your weed leaves are curling down, plus how to diagnose each one and bring your plants back to full health.

Overwatering

If your leaves are curling downwards and the soil feels soggy or heavy, overwatering is undoubtedly the culprit. When the roots are constantly saturated, they can't absorb oxygen properly, leading to drooping, dull leaves that eventually form a claw-like shape.

Symptoms:

• Soil that never seems to dry out
• Soft, limp leaves that curl downwards
• Slower growth and a heavy, waterlogged appearance

Fix:

• Let the soil dry before watering again
• Ensure pots have good drainage holes
• Add perlite or coco coir to improve airflow around the roots

For a complete watering guide to avoid any potential overwatering, check out our guide to watering

Nitrogen toxicity

When cannabis leaves droop and turn a deep, shiny green, your plants may be dealing with too much nitrogen. This common feeding mistake can cause nutrient toxicity, particularly during vegetative growth, and may result in your weed's leaves curling sharply at the tips.

Symptoms:

• Very dark green leaves
• Rigid “clawing” tips
• Slowed or distorted growth

Fix:

• Flush the soil with clean, pH-balanced water
• Reduce the strength or frequency of nutrient feeds
• Switch to a balanced fertiliser designed for cannabis

Learn more about this issue with our dedicated guide to nitrogen toxicity in cannabis plants.

Heat stress

Heat stress can also cause leaves to curl. If you notice drooping during flowering or soon after increasing light intensity, heat stress may be to blame. Cannabis plants can only tolerate so much warmth before they begin to protect themselves by curling their leaves to reduce surface exposure.

Symptoms:

• Curling edges or “canoeing” leaves near the top of the canopy
• Dry, crispy leaf tips
• Symptoms at their worst are directly under grow lights

Fix:

• Raise lights or lower intensity
• Improve air circulation with fans
• Maintain ideal canopy temperatures (around 24–28°C during lights on)

Find expert growing temperature advice in our introductory growing guide.

Root problems

Healthy roots mean healthy leaves. When the root zone becomes compacted, infected, or oxygen-starved, the first visible symptom is the leaves curling down. These issues can stem from overwatering, poor drainage, or pests such as fungus gnats.

Symptoms:

• Weak or thin stems
• Stunted growth and yellowing leaves
• Persistent drooping even with proper watering

Fix:

• Check the root zone for signs of rot or poor drainage
• Transplant to a slightly larger pot with fresh, airy soil
• Avoid overwatering and ensure pots don't sit in runoff water

For more information, see our complete guide on how to identify and fix cannabis root rot.

When to act and what to do

When you see your cannabis leaves curling down, don't rush to change everything at once. Start by observing, then make one adjustment at a time and watch how your plant responds over the next 24–72 hours.

Immediate first checks

• Touch the soil: Is it wet and heavy or dry and airy?
• Leaf tips: Any yellow/burnt tips (possible nutrient burn) or just leaves clawing down?
• Light distance: Are the worst leaves closest to the lamp?
• Growth speed: Drooping and stunted?

Step-by-step fix

1. Pause and observe: Note when and where curling appears; this helps identify whether it's from watering, nutrients, or heat.
2. Adjust watering: Let the soil dry slightly before watering again. Heavy, damp pots are a clear warning.
3. Ease nutrients: Flush with clean, pH-balanced water if leaves are dark and clawed, then feed lighter.
4. Tweak the environment: Raise lights, improve airflow, and keep canopy temperatures around 24–28°C.
5. Check roots: Ensure good drainage and no foul smell, as root rot can mimic overwatering.

For more guidance on growing healthy plants, consult our Grow Weed Hub.

Most cases of downward curling leaves recover within a few days once the underlying issues have been addressed. Patience and small, measured changes are key to success.

When to be concerned

In most cases, cannabis leaves curling down will recover once you've adjusted watering, feeding, or light conditions. However, if the problem continues to worsen even after changes, it's a sign that something deeper is affecting your plant's health.

You should start to worry if the curling becomes more pronounced, the leaves turn yellow or brown, or new growth begins to twist and deform. These additional symptoms often indicate ongoing stress in the root zone, such as nutrient lockout, compacted soil, or an oxygen shortage due to waterlogged soil. If you detect a foul smell, notice mould on the soil surface, or find roots that are brown and slimy instead of white and firm, root rot has likely taken hold. Left unchecked, this can quickly lead to stunted growth and potentially leaf death.

At this stage, focus on restoring balance below the surface. Inspect your pots for proper drainage, refresh growing medium if needed, and ensure humidity and temperature remain within safe ranges. It's also wise to isolate affected plants to prevent the possible spread of any fungal pathogens.

If your weed leaves continue to curl down despite these corrections, consult Zamnesia's in-depth growing resources for expert troubleshooting and recovery advice. Acting early gives your plants the best chance to recover strong and healthy.

Don't let the claw get you down!

Seeing your cannabis leaves curling down can be a stressful sight, but remember: it's your plant's way of communicating. With a few careful adjustments to watering, nutrients, or climate, most issues can be corrected quickly. Once balance is restored, you'll notice new leaves growing flat, vibrant, and full of life again.

Growing cannabis is a learning process, and every challenge makes you a better cultivator. Stay observant, take small steps, and trust your plants to respond.

Ready to give your next grow the best possible start? Explore our full range of cannabis seeds and grow gear and supplies to keep your garden flourishing from seed to harvest.