Plant moisture stress - symptoms and solutions

Many plant enthusiasts often face leaf-related issues and are unsure of the cause. Common symptoms include leaf cupping, browning edges, and curling tips. These issues may be due to water stress, which can be triggered by various factors. In this article, we will explore the common causes of these symptoms and provide simple solutions, ultimately putting the power to correct these issues in the hands of the grower.

Over-Fertilizing​

Cause​

The most common cause of leaf cupping is the overzealous use of too much plant food. This can lead to moisture stress in the leaves, resulting in margin rolling, burning, and a hard, crispy feel.

Solution​

To avoid over-fertilizing, reduce the amount and/or frequency of plant food application. Be cautious, as excessive plant food can also burn the roots, creating further complications.

High Heat​

Cause​

When a plant loses water through its leaves faster than the root system can replace it, leaf margin cupping can occur. High heat is often the culprit behind this issue.

Solution​

Lower the heat and focus on developing a large, robust root system through sound plant culture. An efficient root system will help prevent heat-induced leaf desiccation and margin curling.

High Light​

Cause​

Cannabis plants can suffer from too much light, which can bleach out and destroy chlorophyll, sometimes leading to leaf cupping. Excessive light often accompanies high heat for indoor growers.

Solution​

Reduce the light intensity and concentrate on developing and maintaining an efficient and robust root system.

Overwatering​

Cause​

Overwatering can weaken the root system by depriving it of proper gas exchange, leading to an anaerobic condition that causes root decline, root rot, and leaf stress.

Solution​

Avoid overwatering by allowing the roots to receive adequate oxygen. Be careful not to add more nutrients when overwatering occurs, as this can exacerbate the problem.

Underwatering​

Cause​

Underwatering can stress the plant due to inadequate moisture and compromised carbohydrate production.

Solution​

Increase the watering frequency and, if necessary, use bottom-up watering for organic growers. Monitor the pot's weight to determine when it's time to water and periodically leach the soil to remove excess salts.

Frequently Asked Questions​

1. What is leaf cupping in cannabis plants?​

Leaf cupping, also known as leaf margin rolling, leaf margin burn, and leaf tip curl/burn, is a common issue in cannabis plants caused by factors such as over-fertilizing, high heat, high light, overwatering, and underwatering.

2. How can I prevent leaf cupping in my cannabis plants?​

To prevent leaf cupping, avoid over-fertilizing, maintain appropriate heat and light levels, and ensure proper watering practices.

3. Can excessive light cause leaf cupping in cannabis plants?​

Yes, excessive light can cause leaf cupping in cannabis plants, mainly by bleaching out and destroying chlorophyll.

4. How does overwatering affect cannabis plants?​

Overwatering can weaken the root system, leading to an anaerobic condition that causes root decline, root rot, and leaf stress.

5. How can I tell if my cannabis plant is underwatered?​

If the pot feels light when lifted, it's time to water. Don't wait until the soil pulls away from the sides of the pot or leaves droop before watering.