Greetings, human. We peonies are generally resilient beings, but our leaves turning brown is our primary way of signaling that something in our environment is out of balance. It is a distress call. To understand it, you must think like a plant. Here is what we are trying to tell you.
Our large, lush leaves have a great surface area from which water can evaporate. When our roots cannot draw enough moisture from the soil to replace what is lost to the sun and wind, our leaf edges and tips are the first to suffer. They dry out and turn brown, crisp, and brittle. This is especially common for newly planted peonies whose root systems are not yet fully established. If the soil feels dry and powdery several inches down, you are not hearing our cries for a deep, nourishing drink.
Conversely, you can love us too much with water. Our roots need oxygen as much as they need water. If we are planted in heavy, compacted, or poorly draining soil, or if you water us too frequently, our roots essentially suffocate and begin to decay. This root rot prevents us from absorbing any water or nutrients at all. The signal we send is wilting, yellowing, and then browning leaves that may feel soft or mushy. It is a cruel irony—we appear thirsty, but the problem is actually that we are drowning.
This is a common ailment for us, especially in cool, wet, and humid spring weather. The fungus *Botrytis paeoniae* attacks our tender new shoots, buds, and leaves. You will first see dark brown or black spots or lesions on the leaves or stems. These spots rapidly enlarge, causing the entire stem to wilt and collapse, and the leaves to turn brown and die. It can look as if the plant has been scorched. This fungus thrives in moisture and poor air circulation, so if our foliage is too dense or we are crowded by other plants, we cannot breathe properly and become vulnerable.
Do not confuse us with the apple tree; we have our own version of "measles." Caused by the fungus *Cladosporium paeoniae*, this issue shows up later in the season as glossy, purple-brown, irregular blotches on our leaves. As these spots mature, the center may become light brown or tan, making our foliage look unsightly and eventually causing it to brown and die back prematurely. It weakens us for the following season.
First, become a detective. Examine our leaves and stems closely. Are the brown areas dry or mushy? Are there distinct spots or a general browning? Check the soil moisture. Then, act accordingly. For thirst, provide a deep, slow watering at our base, ensuring moisture reaches our deep roots. For drowning, improve drainage and let the soil dry out. For fungal issues like Botrytis, immediately cut away all affected stems and leaves well below the infection. Dispose of them in the trash, not the compost, to prevent spread. Ensure we have space for air to move through our leaves. In autumn, always cut our foliage back to the ground and remove all debris from the area to deny these fungal foes a place to overwinter. A preventative fungicide applied in early spring may be necessary if infections are severe and recurring.
