The reasons for peonies turning yellow and withering can be roughly summarized into the following five factors:
1. Overwatering: Root rot and yellowing. Peonies are fleshy-rooted green plants and are very susceptible to waterlogging. If the potting soil has poor aeration, waterlogging can easily occur. Therefore, potted peonies must have sufficiently aerated potting soil, and watering should be done thoroughly only when the soil is completely dry. During periods of heavy rain, pay attention to the drainage of potted plants to prevent clogged drainage holes, which can lead to waterlogging and root rot, causing the peony leaves to turn yellow and wither.
For peonies planted in the ground, it is also necessary to raise the soil level. During rainy seasons, drainage ditches should be dug to prevent waterlogging.
2. Excessive drought: While peonies have fleshy roots and are susceptible to waterlogging, they should not be allowed to dry out completely. If they are not watered for a long time, the leaves will also turn yellow and wither.
Therefore, watering should be moderate, adhering to the principle of thoroughly watering only when the soil is completely dry. Do not overwater and allow the peony to dry out completely.
3. Yellowing and Withering Due to Disease
Peony flowers are also susceptible to diseases, leading to significant yellowing and withering. In summer, peonies are easily affected by anthracnose and gray mold, manifesting as numerous brown spots on the leaves or blackening and scorching of the leaf edges.
In hot and humid weather, it's crucial to take preventative measures against peony diseases. Spraying with mancozeb at the beginning of summer is a preventative measure. When diseases occur, early detection and treatment are essential to prevent weakened growth and ensure flowering the following year.
4. Yellowing and Withering Due to Excessive Sun Exposure
Peony flowers prefer a sunny growing environment, but they are relatively sensitive to direct sunlight in summer and should be shaded. Excessive sun exposure in summer can cause scorching of the leaf edges and significant yellowing and withering. This is caused by excessive sun exposure, and timely shading can significantly improve the situation. If left untreated, the damaged leaves may weaken the peony's growth, affecting flower bud differentiation and potentially preventing flowering the following spring.
5. Natural yellowing and withering: Peonies are perennial deciduous shrubs, so they will shed their leaves and enter a dormant state in autumn. Therefore, when peonies turn yellow and shed their leaves in autumn, there is no need to worry too much. This is often a natural phenomenon, indicating that the peony is about to enter a dormant period.
