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Garden Tips

TREE PEONIES NOT REALLY TREES

GARDEN TIPS – written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
published – November 14, 2014

From the prices in a plant catalogs you know that tree peonies must be something special, but why? Despite a name that includes ‘tree,’ this relative of the garden peony is really a deciduous woody shrub.

The tree peony (Paeonia suffruticosa) is slow-growing but eventually reaches a height of six feet. Unlike the herbaceous garden peony, tree peonies do not die back to the ground in the fall. Two other close relatives, Paeonia lutea and Paeonia lutea ludlowii, have been used in tree peony breeding to create hardier and yellow-flowered tree peony hybrids.

Tree peonies are native to northwestern China and are reported to have been in cultivation for centuries in both China and Japan where a number of cultivars (cultivated varieties) have been developed.

Despite their exotic origins and large gorgeous flowers, tree peonies are supposedly not difficult to grow. Tree peonies are hardy to Zone 4 and deer resistant. Tree peonies need a well-drained neutral to slightly alkaline soil that is rich in organic matter. In our region they will need to be provided protection from wind and be located where they receive light or partial shade in the afternoon.

Before planting, loosen the soil in the planting bed to a depth of at least 18-24 inches deep and 12 inches wide. When preparing the soil, mix in organic matter, such as compost. Tree peonies can last many years with good soil preparation and proper care.

When planting bare-root plants, note the swollen area of the stem of grafted plants. This graft should be situated four to six inches below the surface of the soil. Non-grafted plants growing on their own roots should have the swollen portion of their stems located two inches below the surface of the soil. If you are planting a container grown plant, plant it at the same depth it was growing in the container.

Gardeners with herbaceous garden peonies know it is important to not plant them too deep or the plants will not flower. When growing tree peonies it is important to plant them deep enough and not too shallow.

If you buy a tree peony from a specialty nursery, like the Peony Farm in Sequim, WA (ilovepeonies), Klehm’s Song Sparrow (songsparrow.com) or Peony’s Envy (peonysenvy.com), you may be surprised to find that the least expensive ones cost at least $50 and others cost $75 to $200 or more. Sure, the large 6-9 inch single, semi-double, or double flowers are gorgeous and come in beautiful shades of white, yellow, gold, pink, red, purple, pink-purple, and maroon, but why do they cost so much?

First, grafted plants are more labor intensive to propagate, making them more expensive. Tree peonies are slow-growing, putting on only one to six inches of growth per year, lengthening the time it takes to grow them into saleable plants and making them more costly to produce. Finally, these are specialty plants and many of the cultivars are rare and not available in large numbers.

Garden peonies are a favorite of many, but tree peonies can add a touch of the exotic to a garden or landscape, plus they bloom a couple of weeks earlier than garden peonies. I just may plant one in my garden next spring.

Published: 11/14/2014 12:20 PM

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