Why is my purple fountain grass turning brown?

Answered by Robert Flynn

Purple fountain grass (Pennisetum setaceum ‘Rubrum’) is a popular ornamental grass known for its vibrant purple foliage and graceful fountain-like appearance. However, like any other plant, it can experience changes in color and appearance that may cause concern for gardeners. If you notice your purple fountain grass turning brown, there are several possible reasons for this change.

1. Seasonal changes: Purple fountain grass is a warm season grass, meaning it thrives in hot and sunny conditions. As cooler temperatures arrive and winter approaches, it is normal for the grass to go dormant and turn brown. This is a natural response to the changing seasons and does not necessarily indicate any problems with the plant’s health. The brown coloration is simply a sign that the grass has entered its dormant phase. In spring, when temperatures warm up again, the grass will start to regrow and regain its vibrant purple color.

2. Lack of water: Another common reason for purple fountain grass turning brown is insufficient water. This grass prefers consistently moist soil, especially during periods of hot and dry weather. If the grass is not receiving enough water, it may become stressed and start to turn brown. To prevent this, make sure to water the grass deeply and regularly, especially during dry spells. However, be cautious not to overwater, as this can also lead to root rot and other issues.

3. Nutrient deficiencies: Brown foliage can also be a sign of nutrient deficiencies in the soil. Purple fountain grass requires adequate levels of nutrients, particularly nitrogen, to maintain its vibrant color. If the soil lacks essential nutrients, the grass may start to turn brown. Consider conducting a soil test to determine if any deficiencies are present and amend the soil accordingly with organic matter or appropriate fertilizers.

4. Disease or pests: While purple fountain grass is generally resistant to most diseases and pests, certain issues can still arise. Fungal diseases, such as leaf spot or rust, can cause browning and discoloration of the foliage. Additionally, pests like aphids or spider mites may infest the grass and cause damage. Inspect the grass carefully for any signs of pests or diseases and take appropriate measures to control and treat the issue if necessary.

5. Pruning or trimming: Sometimes, the browning of purple fountain grass may be the result of improper pruning or trimming techniques. If the grass is cut back too harshly or at the wrong time, it may lead to stress and browning. When pruning, make sure to remove only the dead or damaged foliage and avoid cutting back the grass too severely. It is best to prune purple fountain grass in late winter or early spring before the new growth begins.

If your purple fountain grass is turning brown, it is likely due to seasonal changes, lack of water, nutrient deficiencies, disease or pest issues, or improper pruning. By understanding these potential causes and taking appropriate actions, you can help your grass regain its vibrant color and health. Remember to provide adequate water, nutrients, and care to ensure the optimal growth and appearance of your purple fountain grass.