In Illinois, small spots may appear just before bloom and merge into large blotches later in the season. A fungus causes it, and the disease looks worse than it acts. The plant itself usually keeps growing, so the real question is how to tell this problem from its lookalikes and how to keep the leaves tidy.
Peony Leaves Turning Brown: What You See
Start with the color and the sheen, because the disease has a very particular look on the two sides of the leaf.
- The top of the leaf shows glossy, purplish-brown spots, often circular at first.
- Flip the leaf over and the same spots turn a chestnut or milk chocolate brown.
- Small spots merge into large, irregular blotches as the season goes on.
- The outer leaves, especially along their margins, tend to show more damage.
- Young stems can carry raised spots that join into short, reddish-brown to purple streaks.
In Illinois, spots on young leaves may appear just before bloom; in Ohio, stem lesions usually appear first and lengthen as the season progresses.
From the almanac
Peonies in your state
The dates on this page depend on where you live. Your state's page carries its frost dates, its USDA zones and the year laid out month by month.
Northeast
Southeast
- Alabama
- Arkansas
- Delaware
- Florida
- Georgia
- Kentucky
- Louisiana
- Maryland
- Mississippi
- North Carolina
- South Carolina
- Tennessee
- Virginia
- West Virginia
Midwest
Southwest
West
Pacific Northwest
Canada
Peony Leaves Turning Brown or Something Else?
Several peony problems share a few symptoms with leaf blotch. Checking the surface of the leaf and the spot on the plant keeps you from treating the wrong thing.
Both gray mold and powdery mildew are real lookalikes, and each leaves a distinct signature once you know where to look.
| Looks like | How to tell them apart |
|---|---|
| Powdery mildew | Starts as small white spots that spread into a white-to-gray powdery coating over the whole leaf, which leaf blotch never produces. |
| Gray mold (Botrytis) | Brown or purplish-brown circular spots, sometimes followed by brown, rotting buds. |
| Leaf blotch | Glossy purplish-brown spots on top, chestnut-brown underneath, with reddish stem streaks. |
Phytophthora blight also deserves a look if a shoot collapses or the base of the plant is affected. Black lesions several inches long on young shoots, along with browning at the base of leaves, point toward that problem and away from simple leaf blotch.
What Causes Peony Leaves Turning Brown, and Where It Is Worst
The usual cause is a fungus, Graphiopsis chlorocephala, formerly called Cladosporium paeoniae. The same disease goes by leaf blotch, measles, or stem spot, and it spreads when the weather is warm and humid.
No single region owns this disease. It shows up wherever summers turn muggy, and in Illinois, leaf blotch and powdery mildew appear fairly regularly on peonies during the summer months.
Timing matters for how much to worry. In Illinois, early infection can look unappealing and may reduce plant vitality, while infection that appears late in the season is usually not a problem for growth. Despite the dramatic look, leaf blotch does not significantly affect plant vitality.
How to Treat Peony Leaves Turning Brown
Start by confirming leaf blotch from its distinctive spots and streaks.
- Confirm the diagnosis by checking the underside of the leaf and the stems, so that you treat leaf blotch and not mildew or a blight.
A collapsed shoot, suddenly rotting buds, or an affected crown points to a different problem.
How to Prevent Peony Leaves Turning Brown Coming Back
Watch for the glossy spots and reddish stem streaks that identify leaf blotch.
Where This Comes From
These symptoms and causes are based on plant-disease guidance. Check local guidance for timing and treatment rules.
Common Questions
Should You Cut Back Peonies with Brown Leaves?
Can Brown Spots on Peony Leaves Kill the Plant?
Leaf blotch does not significantly affect plant vitality, so the plant usually survives. A collapsing shoot or a rotting crown is a different situation and calls for a closer look.
Why Are Peony Buds Turning Brown and Rotting?
Brown, rotting buds point to a blight rather than leaf blotch. Botrytis is more likely than Phytophthora to cause bud rot, and both can turn buds brown suddenly at any stage of development.