When Are Peonies in Season?

If you enjoy showy, colorful flowers, peonies (Paeonia spp.) could be a perfect choice for your garden. Bushy or tree-form plants that are available in several types, they have flowers in different styles and are generally hardy in U.S. Department of Agriculture plant hardiness zones 3 through 8, depending on their variety. Mostly herbaceous perennials, with leaves and stems that die to the ground in winter, peonies usually grow from spring into fall, but their growth varies a bit at different times.

Peonies usually put out new leafy growth in early spring, when their shoots begin pushing through the soil surface. One type, the tree peony (Paeonia suffruticosa), has woody stems that don't die to the ground each year; most of its new growth appears at stem tips in spring. It is hardy in USDA zones 4 through 8 or zones 5 through 9, depending on the source. Peony flowers include bushy, double and single blooms with five petals surrounding a tuft of showy stamens. The semi-double flower forms have a single outer row of five guard petals surrounding modified stamens that may resemble modified petals. Peony flowers usually remain open about one week in spring and summer, with some varieties blooming early, others in the middle of that period and some a bit later in summer.

Peony plants continue growing throughout summer, even after they finish flowering. Exposure to full sun promotes their best flowering. It also encourages the plants to produce a lot of leaves, which helps to boost their blooming the next year. Peonies tolerate partial shade, but it may lessen their size and the number of their flower buds. Each spring, add a 3- to 4-inch-thick layer of organic mulch -- such as straw or shredded bark -- on top of the soil under each plant's canopy to help conserve soil moisture and to reduce weeds, which compete for soil nutrients. As summer's end nears, peonies tend to put out less new growth and prepare to enter cold-weather dormancy.

As summer ends and fall begins, the growing season ends for the peony plants. Removing the mulch from their soil surface in fall discourages the growth of fungal diseases. When the weather cools, cut herbaceous perennial peonies' stems to within 3 inches of the ground, destroying the stems and cleaning your trimming tools with rubbing alcohol before each cut to prevent the spread of plant diseases; clean the tools in the same way after you finish trimming. Tree peonies need only their dead and diseased stems trimmed back, preserving their healthy stems to promote future growth.

Peonies bloom in many colors, including shades of pink, fuchsia and red as well as white and bicolors, with petals and stamens in contrasting colors. A practice called "disbudding" can help promote especially large flowers. It requires removing all side buds on each stem as soon as they develop, leaving only the single, terminal bud. Support each stem by tying it loosely with a soft tie to a narrow stake sunk a few inches into the ground near the stem. After each flower wilts, remove it, leaving as many leaves on its plant as possible; that technique helps to prevent seed development, which uses up the plant's food reserves and can slow its growth. You also can boost peonies growth by fertilizing them in early spring with a low-nitrogen formula such as 5-10-10, applying about 1/2 cup of the dry, granular fertilizer per plant; scratch the fertilizer gently into each plant's soil, and water the fertilized soil well.