The peony is a beloved perennial, cherished for its large, fragrant blooms that signal the arrival of late spring and early summer. While the flowering period is relatively short, the care provided immediately after the petals drop directly influences the abundance and quality of next year’s display. During this post-bloom period, the plant shifts its focus entirely to energy storage, requiring attention to foliage health, water, and nutrient levels. Consistent care through the summer and fall is the foundation for robust growth and spectacular flowers the following season.
Immediate Care: Deadheading Spent Blooms
The first step after the blooms fade involves removing the spent flower heads, a process known as deadheading. This action redirects the plant’s energy reserves, as peonies will not produce more flowers in the current season. If old flowers remain, the plant attempts to produce seeds, an energy-intensive process that depletes resources needed for root and bud development for the following year.
To deadhead properly, use clean, sharp shears to snip the flower stem just above the nearest set of healthy, full leaves. Only remove the flower structure and a small portion of the stem, leaving the majority of the foliage intact. This technique prevents seed pod formation while maximizing the leaf surface area available for photosynthesis throughout the summer. Discard the spent blooms away from the garden area, as they can harbor fungal spores that might cause disease.
Maintaining Healthy Foliage Through Summer
The foliage that remains after deadheading plays a vital role throughout the summer months. These leaves are the plant’s energy factories, converting sunlight into carbohydrates through photosynthesis, which are stored in the roots for winter dormancy. Keeping this foliage green and healthy until the first frost determines next season’s bloom performance.
Peonies benefit from deep, consistent watering, especially during dry summer periods. Instead of light, frequent sprinkling, soak the soil deeply every week or two to encourage downward root growth and better drought resistance. Ensure the water reaches the entire root zone, applying it directly to the soil surface rather than wetting the foliage, which can encourage fungal issues.
A light application of fertilizer immediately after blooming supports the summer’s energy storage efforts. Peonies thrive on a blend low in nitrogen (N) and higher in phosphorus (P) and potassium (K), such as a 5-10-10 or 4-10-10 ratio. Excessive nitrogen encourages lush leaf growth at the expense of next year’s flower bud development. Apply a slow-release granular fertilizer, such as bone meal, around the drip line, keeping the granules away from the crown and stems.
Summer requires vigilance for common fungal diseases, notably powdery mildew and botrytis blight. Powdery mildew appears as a grayish-white coating on the leaves, typically in late summer, and can reduce the plant’s photosynthetic capacity. Botrytis blight, often called gray mold, is more damaging and can cause stems and leaves to blacken, wilt, and collapse.
If signs of disease appear, immediately remove and destroy the infected foliage by placing it in the trash, not the compost pile, to prevent fungal spores from spreading. Maintaining good air circulation by avoiding overcrowding and ensuring the soil surface dries between waterings are the best preventative measures. Chemical treatments are usually reserved for severe or recurring infections, but maintaining overall plant health is the best defense.
Preparing Peonies for Winter Dormancy
As temperatures drop and the growing season ends, the final step is preparing the plant for winter dormancy. This transition usually occurs in late fall, typically after the first hard frost, which signals the plant to withdraw all remaining energy from the leaves and stems back into the root system. The foliage will naturally turn yellow or brown, indicating the storage process is complete.
Once the foliage has completely died back or after a hard frost, cut the stems down to approximately one to two inches above the soil line. This practice is fundamental for disease management, as it removes above-ground material that could harbor fungal spores, such as those causing botrytis or powdery mildew, over the winter. Collect all cut stems and leaves and dispose of them outside of the garden area.
For mature, established peonies, additional winter protection is often unnecessary, as they are cold-hardy and require a period of cold temperatures to set blooms for spring. If you live in an area with inconsistent winter snow cover or are tending to newly planted divisions, apply a light layer of organic mulch like straw or shredded leaves after the ground freezes. Avoid covering the plant’s crown directly with mulch, as this can trap excess moisture and lead to rot or interfere with the cold period required for flowering.