Woody Paeonia

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Woody Peony (tree peony) Culture and Care

Diversity and Beauty-Not Difficult to Grow!

While often marketed as ‘Tree Peonies’ this group is best referred to as ‘Woody Peonies’. Seldom do woody peonies become tree size in stature, but rather, are small shrubs-most only growing to 3 to 5 feet in height in good conditions. Plants may have many stems and be wider than they are high. They are characterized by woody stems that persist through winter which produce flowers in early spring. Flowers are very large in comparison to other peonies and have a wide variety of forms and color-all depending on the specific cultivar. For more detailed information, select the “Culture & Care Guide” at right. This guide may also be downloaded free of charge from within our Woody Peony Catalog.

-Major Points of Culture-

Typically, woody peonies do not require much special treatment and their culture is fairly intuitive for the gardener, with some exceptions. However, they are a plant that is not commonly grown at this time in most gardens, thus some basic cultural information related to them may be helpful.

Plant in a well-drained site, which never becomes wet and allows roots to prosper. It is especially important to know the winter season’s site properties, as this is the period in which many soils may become saturated. Typically, gardeners do not notice winter soil conditions due to inactivity in the garden, thus extra attention is required to the site before planting. Winter kill from excessive moisture is one of the most common reasons for woody peony plant failure.
Select a site which does not have competition from other plants – especially shrubs and trees. Lilacs and some other shrubs produce root systems which compete with the roots of peonies for the same nutrients.
The planting site should be one not subject to late spring frosts, as this may prevent young buds from developing further. Low sites are most often impacted by late frosts.
Provide a site with full sun or very light shade. Those planted in hot summer climates are best when some shade is provided to protect the leaves from burning.
Water only if needed. Woody peonies are quite drought resistant and resent wet feet. Keep plantings well clear of automatic sprinklers, such as those to keep lawns green and growing. Do not plant near downspouts and roof driplines.
Provide a site which will have good air movement and is not crowded. Good air movement around plants prevents foliar and stem diseases.
Plant in predominately native soil found at your location, if at all possible. Amending soils heavily with organic material in the planting hole often creates a ‘BIRD BATH EFFECT’ in which water is held and causes rooting issues. The goal is to create a homogenous soil in which roots do not encounter pockets of variable constituents (roots have to adapt to each soil variable they encounter). If amending the soil, do so broadly over the entire planting area, not just the planting hole. DO NOT USE excessive amounts of peat as an amendment – it holds water and is acidic. Peat is a very good dry packing material for shipping peonies due to its antiseptic properties, but is not useful as a growing medium by peonies. However, peat may be well mixed with native soils in very minor amounts to improve soil structure without detriment.
Soils which support best growth have a near neutral pH (6 to 7). Clay soils are often highly fertile and may support excellent growth, but may hold excessive water which damages roots. Avoid soils with fresh and excessive organic material included, as this may promote disease. Soil predominantly composed of sand are not particularly fertile and peonies will not prosper.
Removal of old, dead or weak stems allows new growth to progress unimpeded and promotes new healthy stem production. Woody peony stems are not particularly long lived in most situations. If planted deeply, any woody peony which loses its stems will almost always regrow from basal shoots, given proper growing conditions.
Containerized culture is not recommended and less than positive results may be expected over time. Plant woody peonies in the ground where they may grow their extensive root systems which will feed their large stems.
Fertilize only if necessary. Allow plants to establish at least 5 years before considering the application of fertilizer (true for all peonies). Avoid the use of fresh manure, as this may burn root systems or carry diseases. Woody peonies grow slowly the first few years and their growth is always measured, thus it is unlikely any large increase in growth will ever be noted after fertilizing. High nitrogen fertilizers, as those found in lawn and bedding plant ratios, are to be avoided. High nitrogen fertilizers will promote soft growth susceptible to disease.
Plant them in the late summer into the fall season as soils begin to cool. This period of time is when root growth occurs. The month of planting will depend upon region the garden is located. Those in the northern tier of the United States usually plant at the end of September to mid-October. More southerly locations will have best results in mid-October to November. Spring planted woodies can be expected to flounder (or die) and do not produce roots until soils begin cooling in late summer – spring planting is not recommended and will not produce a larger plant the following year.
Avoid the use of mulch near woody peonies. Mulch often holds excessive moisture and does not allow for good aeration of the soil below it, creating a wet situation. Mulching plantings has become popular and is one of the main causes related to plant failure and development of disease. If plantings are mulched, make sure it is applied no closer to the woody peony plant than 16 inches. Additionally, many of the commonly available mulches are now treated with preservatives and coloring to enhance their longevity and visual appeal, these may be detrimental peony growth. Mulch contamination from oils, herbicides and other contaminants may occur at the production site before it is sold to end consumer – these may also present issues with its use. Lastly, some wood mulches may be produced from tree species which contain chemicals which adversely impact peony growth (ex: Black Walnut).