Tree Peonies: Buying and Growing
What is a tree peony?
Tree peonies are not trees. They are deciduous shrub perennials. They typically develop several woody stems, which may live and increase in size for years or which may be replaced by new stem growth from the roots. In colder climate zones, such as those north of USDA zone 6, unprotected stems may die back to the snow line in winter, but shall be replaced by new growth in the spring. Most tree peonies grow to about 3-4 feet tall and spread about equally as wide. If the plant is not killed down by cold weather, it may reach up to 6 feet tall and wide.
There is an extensive variety of colors due to hybridization and cultivar selection of tree peonies. Colors can range from blackish-red to shades of pinkish-yellow or sweet cream. In the center of the petals is a golden-crown of anthers. The flowers are large, about 8-10 inches in diameter. They can vary significantly in texture and appearance: smooth or crinkled; velvety, silky, or satiny; wavy, twisted, or frilled; wispy or sturdy; single, semidouble, or double. Some varieties emit a heavenly fragrance, while others exude a piney odor.
One flower usually grows per stem near the stem top. The blooms remain open for around 5-7 days, and the bloom period spans about 10-12 days. The bloom period can be extended by selecting species with overlapping bloom times.
Tree peonies are native to China. The Chinese and Japanese have developed numerous hybrids. The most commonly available tree peonies are the Japanese cultivars. These have fine foliage, sturdy upright stems, and a huge selection of colors. The Japanese varieties are considered the easiest to grow.
Buying and growing tree peonies
Once, tree peonies were difficult to find and extremely expensive. Today gorgeous tree peonies may be purchased online or through mail order catalogues. Sometimes, you can be lucky enough to find them at local nurseries. Tree peonies are usually propagated by bud-grafting onto the rootstock of an herbaceous peony. It takes two years for the plant to grow enough to be sellable. They usually bloom 2-3 years after transplanting, though they bloom lightly the first spring after being planted. Younger plants are easier to transplant than older ones of blooming age.
Tree peonies are rugged and adaptable, but they do best in uncrowded quarters where they do not have to compete for root space. Since they can spread up to 6 feet it is important to plant them at least 12 feet away from any tree and at least 2-3 feet from a fence or wall. Excessive sun will scorch foliage, and too much wind shall batter and break the stems. Planting must be done in a protective site shaded from midday sun or northern winds. Walls or fences provide good wind breakers.
Tree peonies require well-drained, moisture-retentive loam, preferably with a neutral to slightly acid ph. Avoid areas where water stands even if only for a short period of time. A good soil mix consists of equal parts topsoil, compost, and peat moss. Planting should be done in September or October to give the roots time to establish before winter freezing. Spring planting should be avoided if possible.
To plant, dig a 2 foot wide by 2 foot deep hole. Use a good soil mix, and add in about 2 lbs. of bone meal. Set the junction between stem and roots 5 in. below ground level. This will encourage the plant to grow roots on its own stock. When the hole is filled to the proper amount, position the plant, and fill in soil around it. Do not pack the soil down. Leave it loose and flood the hole with water. Once the water has drained, add enough soil to fill the hole completely and create a small mound of soil around the plant. Then mulch heavily to retain soil moisture about 2 in.
Tree peonies require little care. Pruning is not necessary, unless you wish to remove seed heads for aesthetic purposes. They only need to be watered when soil is harshly parched. Also, each year provide a sprinkling of fresh bone meal after gently cultivating about 1 in. into the soil around the plant base. With these simple steps fertilizer should not be necessary.
In the spring, sit back and enjoy your luscious tree peony blooms.