Thursday, June 17, 2010

Plant Care Profile: Tree Peony (Paeonia suffruticosa)

After featuring tree peonies (Paeonia suffruticosa) as part of my post on the Lan Su Chinese Garden in Portland, Oregon, I thought it might be a good idea to do a care profile on these beauties. I think there are a few flowers - and even fewer that will tolerate a Zone 4 winter - which can compete with tree peonies for sheer showiness or flower size. The plants can be quite pricy and nurseries and garden centers still often carry them as somewhat of a rarity but they are almost care-free once established and grow quite vigorously if they are happy.

Yellow-flowered tree peonies in pots flanking the entrance to the Hall of Brocade Clouds at the Lan Su Chinese Garden in Portland, Oregon, Zone 8b

Origin: Paeonia suffruticosa has been in cultivation in China for millenia and it appears to have been derived from one or several of various similar species found there.
USDA Hardiness Zone: Paeonia suffruticosa is hardy to Zone 4a according to most sources, though some even claim hardiness to Zone 3b.

A close-up of a bloom of the yellow tree peonies at the Lan Su Chinese Garden

Size: Depending on the variety, tree peonies can vary between 2' (ca. 60cm) and 8' (ca. 2.4m) in height and shrubs can be up to 6' (ca. 1.8m) across.
Flowering Time: Tree peonies will flower in mid- to late spring depending on local climate, usually a few weeks earlier than herbaceous peonies.

My own semi-double Paeonia suffruticosa specimen in my family's previous southeast Michigan garden in Zone 6a the first year it flowered

Light Requirements: Tree peonies prefer full sun, though they will put up with a little bit of shade. While it does not kill the plant, even partial shade is likely to lead to reduced flowering.
Soil Requirements: Ordinary, well-drained garden soil suffices, though Paeonia suffruticosa also appears to benefit from added organic matter, such as top dressings of compost and leaf mulch.

A close-up  of the tree peony in my family's former Michigan garden

Siting in the Garden: Tree peonies should be planted in a sunny, somewhat sheltered spot with enough space for their often ample growth.

A very old specimen of Paeonia suffruticosa with enormous pale pink flowers in a frontyard in Niagara-on-the-Lake, Ontario, Zone 6a

Care: Tree peonies should be planted in spring or early summer so they have plenty of time to get established and, as with most shrubs and perennials, it is a good idea to mulch around them after planting to conserve moisture and keep soil temperatures even. Plants are usually sold potted and but sometimes bare-root plants can also be found. While these might be considerably cheaper, they should only be bought if they have several strong shoots with healthy, plump buds on them and even then it might take one or two years of growth until they will flower for the first time. Once established the plants need very little care; they should be watered in times of extended drought and benefit from continued mulching as well occasional top dressings of compost or fertilizing with some bone and blood meal worked lightly into the soil around the plant. Due to the heavy flowers the plants also might need staking while they bloom and unless seeds are wanted they should be dead-headed after flowering. Pruning is possible if plants get too large but otherwise not necessary except to remove dead shoots on the sparsely branched shrubs.

A close-up of a flower of the pink tree peony in Niagara-on-the-Lake

Propagation: Paeonia suffruticosa can be propagated from seed but the seeds need to be very fresh and either have to be sown outdoors in the fall in an area that experiences winter cold or require stratification. Varieties also do not come true from seed, so grafting, air layering, and cuttings are more common methods of propagation, though these, too, are challenging and might not be practical in the home garden.

A white variety of Paeonia suffruticosa in Niagara-on-the-Lake

Uses in the Garden: Paeonia suffruticosa is stunning while in flower and makes a nice backdrop to other flowers even after its own flowers are spent due to its beautiful, finely divided foliage.  It is well suited to the middle or the back of perennial and shrub borders but also looks good in a bed of its own, especially if different varieties are planted together.

A semi-double variety of Paeonia suffruticosa with flowers streaked in white and red, photographed in Newport, Rhode Island, Zone 7a

The Garden Plants of China by Peter Valder, Timber Press, 1999.

3 comments:

  1. Quick comment on propagation: they are not easy to propagate, which is why they are so expensive. Commercially, they are grafted onto the roots of herbaceous peonies.

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  2. I figured, hence the very perfunctory information.

    Thank you for visiting my blog - yours is wonderful, and I am quite jealous of the newest batch of Arrowhead Alpines acquisitions!

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  3. I have one of these on the back of our acreage and I have NO idea how it got there!!

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