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6 Reasons Why Peony Leaves Turn Brown (And How To Fix It)

Peonies are known for their large, stunning blooms and go dormant in winter. They come in two main varieties: herbaceous peonies and tree peonies. Today, I’ll share insights into the factors affecting peony leaf health.

Leaf browning in peonies can be due to various diseases. If this happens, relocating your peonies to a spot with at least 6 hours of sunlight daily, ensuring well-draining soil, and applying fungicide can help combat the issue.

It’s natural for peonies to die back in winter, leading to brown leaves that eventually drop. Tree peonies will leave behind a woody stem, while herbaceous peonies retreat entirely below the surface.

Let’s dive into the reasons behind peony leaves turning brown and the steps you can take to address this.

1. Diseases

peony leaves turning brown

Peony leaves turned brown leaf blotch.

Diseases can affect a single peony plant and potentially spread to others nearby. Common issues include leaf blotch, powdery mildew, black spot, and fusarium, as noted by the American Peony Society.

Leaf blotch manifests as initial brown spots on the leaves, which, if not addressed, expand and affect more leaves.

Black spot is characterized by dark brown or black spots with a lighter brown halo. Powdery mildew and other molds are caused by spores that settle on the leaves, depleting them of nutrients and causing browning.

Fusarium, a soil-borne fungus, remains dormant for extended periods. Its presence is hard to detect, with browning and wilting leaves being the primary signs.

Here are some solutions:

  1. Use a multipurpose fungicide spray on the plant.
  2. Avoid wetting the leaves during watering to prevent disease spread.
  3. Cut away and dispose of infected parts to stop the disease from reaching other plants.
  4. Improve airflow by pruning surrounding plants.
  5. If the problem continues, consider replanting in fresh, fusarium-free soil.

2. Root Issues

peony leaves turning brown

Peony leaves turned brown because of root issues.

Peony leaves may turn brown if they’re not receiving enough water at the roots. This issue can stem from insufficient watering, competition from weeds around the plant’s base, or clay-heavy soil that impedes water flow.

The first sign of dehydration is the plant beginning to droop. With ongoing water shortage, the leaf tips turn brown, and the affected areas dry out and become brittle.

Here are some solutions:

  1. Water your peonies once the top 1-2 inches of soil feel dry.
  2. Apply a layer of mulch around the plant’s base to help retain soil moisture.
  3. Provide approximately 1 gallon of water per bush.

3. Not Enough Sunlight

The two types of peonies have different sunlight needs. Tree peonies, which keep their stalks, thrive in both full sun and partial shade throughout the day.

Sunlight not only energizes the plant but also helps to dry the leaves, reducing the risk of diseases that can cause leaf browning.

However, insufficient sunlight alone won’t directly cause the leaves to turn brown. If peonies are placed in complete shade, they might start to decline, particularly the herbaceous varieties. This decline often begins with the leaves turning brown before they eventually fall off.

Here are some solutions:

  1. Move herbaceous peonies to a location where they can enjoy at least 6 hours of full sunlight each day.
  2. Plant tree peonies in areas that receive partial to full sunlight.

4. Poorly Draining Soil

peony leaves turning brown

Peony leaves turned brown due to poorly draining soil.

When peonies are planted in soil that doesn’t drain well, they’re at risk of developing root rot. This condition prevents the roots from adequately supplying water to the leaves, leading to visible signs of distress. You might notice the leaves turning yellow with brown edges, and brown spots could also emerge on the leaves.

Here are some solutions:

  1. Relocate your peonies to well-drained soil.
  2. Before replanting, remove any decayed roots.
  3. Provide some shade for the peonies during the first few weeks after transplanting to help them recover.

5. Pest

peony leaves turning brown

Peony leaves turned brown because of pests.

Peonies are known for their resistance to pests. However, they can occasionally become hosts to pests that drain essential nutrients. Fortunately, these pests are quite easy to identify and manage. Key indicators include spider-web-like formations under the leaves, bumps on the stems, and a brown or black crumbly substance on the plant.

These bumps are actually scale insects feeding on the plant’s nutrients. Additionally, small white insects, known as mealybugs, produce a white silk and can lead to brown patches on the leaves due to nutrient depletion.

Here are some solutions:

  1. Use an insecticidal spray or neem oil on the affected plant.
  2. If there’s a significant pest presence in the soil, it might be best to replant your peonies in fresh soil.

6. Overfertilization

Ideal peony soil mirrors the texture of the compost available at garden centers. Often, there’s no need to supplement this with extra fertilizer. While some plants benefit from additional nutrients, over-fertilizing can harm peonies by damaging their roots.

This damage impedes the plant’s ability to absorb nutrients, leading to brown tips on the leaves and, over time, causing the entire leaf to brown.

Here are some solutions:

  1. Transplant peonies into fresh soil that has the consistency of commercial compost.
  2. Avoid adding extra fertilizers to let the soil naturally find its balance.

Stephen Klyce

Saturday 15th of July 2023

My peony leaves turn brown as soon as I irrigate with well water spray. The well water pH seems neutral. This year I had well problems and could not irrigate and the leaves on the peonies have stayed healthy and green. The well water also turns the Japanese red maple leaves brown as well, but does not cause problems with the vegetable garden greens from chard to squash. Any ideas?

Igor Viznyy

Sunday 23rd of July 2023

Hi Stephen. The issue with your peony leaves turning brown after irrigating with well water may be related to the presence of certain minerals or substances in the water.

A. Hughes

Saturday 20th of May 2023

The new growth on my Peony went brown and died back to the root system. I dug it up today and the top of the root system was brown but lower down was white and 'crunchy'. It was planted in an area that was originally a rubber lined pond that was pierced and then filled with soil and turned into a flower bed. The first year it flowered ok but then reacted as described. However,I think the 'soil' is not particularly good as it tended to dry out quickly.