Peonies are long-lived herbaceous perennials cherished for their large, often fragrant blooms that announce the arrival of late spring and early summer. A single plant can thrive and flower for a century or more, making it a permanent fixture in the garden landscape. Establishing and maintaining a peony requires specific, methodical care to ensure a lifetime of abundant flowering.
Establishing the Peony: Site Selection and Planting
Peonies demand a location that receives a minimum of six hours of direct, unfiltered sunlight each day to produce robust stems and plentiful flowers. They also require well-drained soil, as sitting in consistently wet conditions can quickly lead to root rot and plant failure. If your soil is heavy clay, amending the planting area with compost or installing a raised bed will improve aeration and drainage.
The most common reason for a healthy peony failing to bloom is improper planting depth. The root division, often called a bare root, has small reddish or pink buds known as “eyes.” These eyes must be positioned no more than one to two inches below the soil surface. Planting the eyes too deeply encourages the plant to put energy into foliage production instead of flower bud formation.
When planting multiple divisions, space them three to four feet apart to allow for mature growth and ensure adequate air circulation between the plants. Proper spacing helps to minimize the risk of fungal diseases later on. After setting the root at the correct shallow depth, backfill the hole gently and water the area thoroughly to settle the soil around the roots.
Routine Maintenance: Water, Feed, and Support
After initial establishment, peonies are surprisingly drought-tolerant, but they benefit from consistent deep watering, particularly during dry periods and throughout their first year. Aim to provide about one inch of water per week, ensuring the moisture soaks down to the deep roots. When watering, apply the water directly to the soil around the base of the plant to keep the foliage dry, which helps prevent fungal issues.
Peonies are light feeders and generally require minimal fertilization, especially if the soil was properly enriched with compost at planting. Over-fertilization, especially with high-nitrogen formulas, can lead to excessive, floppy foliage growth at the expense of flower production. If a plant appears to be struggling, a light application of a low-nitrogen, balanced fertilizer or bone meal is best applied in the fall or very early spring.
Many classic herbaceous peony varieties produce large, heavy double flowers that are prone to flopping over, especially after a rainstorm. Providing physical support is highly recommended to prevent stems from snapping and blooms from resting on the ground. Install a metal peony cage or hoop very early in the spring, before the stems grow more than six inches tall.
Installing the support early allows the emerging stems to grow naturally up through the grid or ring, concealing the support structure and providing continuous reinforcement. For rows of plants, corralling them with stakes and twine is a cost-effective alternative. This proactive measure ensures the plant’s weight is managed before the flower buds develop.
Seasonal Pruning and Winter Preparation
During the flowering season, deadheading spent blooms helps to maintain a tidy appearance and directs the plant’s energy away from seed production. Use clean, sharp pruners to snip the faded flower head just below the bloom, cutting back to the nearest set of healthy leaves. The remaining foliage must be left intact throughout the summer and fall, as it continues to photosynthesize and store energy in the roots for the following season’s blooms.
The most important annual pruning task occurs in the fall, following the first hard frost. Once the foliage of herbaceous peonies turns yellow or brown and dies back, cut the stems down to about three inches above the soil line. This thorough fall cut-back is a critical sanitation measure.
Removing all the dead foliage and plant debris prevents fungal spores, particularly those of Botrytis blight, from overwintering in the garden and infecting the new shoots in the spring. The cut stems and leaves should be disposed of in the trash, not added to the compost pile, to avoid reintroducing pathogens. In regions with extremely cold winters, a light layer of mulch can be applied over the crown after the ground freezes to offer extra insulation.
Addressing Common Peony Issues
One of the most frequent concerns for new growers is the presence of ants crawling on the developing flower buds. Peony buds secrete a sugary nectar on their outer sepals, which attracts ants. The ants are completely harmless to the plant and are not required for the buds to open.
A more serious issue is Botrytis blight, a fungal disease that thrives in cool, wet conditions. It is often responsible for buds turning brown and failing to open, or for stems collapsing near the soil line. Good cultural practices are the primary defense, including ensuring excellent air circulation, avoiding overhead watering, and performing the annual fall clean-up. Infected stems should be removed immediately and discarded upon first sign of the characteristic brown spots or gray mold.
If a mature, established peony is not blooming, the cause is almost certainly related to environmental factors. The lack of flowers can typically be traced back to the eyes being planted too deeply, a sudden increase in shade from nearby trees, or the plant being too young. Addressing the planting depth in the fall is the most effective corrective action.