During your cannabis grow it’s important to constantly be checking up on how your plants are getting along. If you begin to notice that your plants leaves are curling upwards in a canoe type shape, then you really need to take action before it’s too late!

This condition is often referred to as “The Claw” or “Canoeing” due to the curled shape. This is a tell-tale call for help from your plants and means that something is irritating them during their growth cycle.

cannabis leaves curling up

The difficult part about diagnosing what the issue is, is that this curling condition can be caused by multiple different ailments.

In this guide, we’ll be breaking down the most common reasons your plants might be curling, how to diagnose them, and how to save your grow!

Most Common Causes of Cannabis Leaves Curling:

  • Overwatering
  • Over-Fertilization
  • Heat Stress
  • Windburn

How to Fix Curling Cannabis Leaves:

Obviously your plant can’t leave you a note telling you what it doesn’t like, but they will do their best to leave you little signs indicating what it doesn’t like.

If you notice that your plants leaves are curling upwards or curling downwards, this means that it is irritated or in distress. You really need to stop and find what’s causing the irritation before the damage is irreversible.

1. Overwatering:

One of the most common causes of curling or canoeing leaves is due to overwatering. Cannabis plants use their roots deep in the soil to absorb nutrients and oxygen, and when the soil is overwatered, it prevents the plants from being able to absorb these pockets of oxygen.

cannabis leaves curling down during flowering

Along with this, by having too much water in the soil it puts your plant at risk of being invested with harmful fungi and bacteria which could lead to disease.

Signs You’re Overwatering Your Cannabis Plants:

  • Drooping or curling leaves.
  • Plants will droop or curl more soon after watering.
  • Can eventually lead to leaves turning yellow.
  • Pooling water in the soil even days after watering.

Solution:

Ensure that you are using proper pots and containers to store your plants. You want an excess water escape at the bottom of your container so that excess water can leave the container rather than sit and pool.

Slow down your watering frequency, and give your plants a bit of time to recover. You shouldn’t water the plant again until the soil is dry up to about an inch deep into the soil.

2. Too Much Fertilizer:

Generally speaking, fertilizer is a great way to give your plants a healthy and nutritious foundation for growth. That being said, over-fertilizing can actually cause quite a bit of damage to your cannabis grow, and can cause this canoeing of leaves.

Over-fertilizing can actually cause fertilizer burn, where the foundation of fertilizer turns into a toxic like pool, which causes your plan to sit and suffer.

Signs of Over-Fertilization:

  • Drooping or curling leaves.
  • Burn-like marks.
  • Very dark shades of green splotches.

Solution:

Over-fertilization can be difficult to identify, but it is one of the most common causes of curling cannabis leaves.

It’s really important to do your research and stick to the feeding charts for your specific strain and your specific fertilizer.

If you’re seeing signs of over-fertilization, then you should stop giving it additional fertilizer and ensure that your plant has enough water to help flush out the extra fertilizer from its system. Be careful of overwatering, but also ensure that your pot or container has a way for extra water to escape.

3. Heat Stress:

Each cannabis strain will have its preferred climate and growing temperatures for optimal growth. If they’re subjected to temperatures that are warmer than what they prefer, then they can begin feeling heat stress. Most strains will begin feeling heat stress from temperatures above 85 degrees Fahrenheit (30 C.)

weed leaves curling

Generally if you start to see your cannabis leaves curling downwards with brown edges, this is typically a sign of heat stress.

Signs of Heat Stress:

  • Curling or canoeing leaves.
  • Yellow or brown spots or edges.

Solution:

The solution of heat stressed cannabis plants is generally pretty straight forward.

If you’re growing outdoors, then I’d recommend placing a tarp over the plants during the hottest periods of the day. Just providing the plants with a few hours of shade should be enough to let them recover.

If you are growing indoors or growing weed in your closet, then you’ll simply have to adjust the temperature and ensure that it’s receiving proper airflow.

It’s also been reported that seaweed kelp extract can help plants recover from heat stress rather quickly!

4. Windburn:

If you’re growing outdoors, and you live in a windy climate, it’s possible that your plants have gotten windburned.

This will generally result in your leaves curling upwards to try to protect the plant from these strong winds. Windburned cannabis leaves don’t always look exactly like a traditional curling leaf, they can also reposition themselves to try to stay out of the wind.

Signs of Windburn:

  • Curling or canoeing leaves.
  • Leaves curling upwards to try to protect the plant.
  • Leaves positioning themselves away from the direction of the wind.

Solution:

If you’re growing outdoors, then providing a little protection from the wind can make a world of difference. You could put up a tarp that helps cut the wind and give them a bit of cover.

That being said, you’ll have to inspect your plant and look for leaves that have been overly damaged, because these might need to pruned to help protect the rest of the grow.

Final Thoughts on Curling Cannabis Leaves:

Overall it can be difficult to diagnose the exact reason why your cannabis plants might be curling, but hopefully this guide has given you a bit of clarity and helped you come to the likely cause.

Thankfully, the quicker you spot these issues, the quicker you’ll be able to correct the issue and help save your grow.