PBS TOW
Peonies on the West Coast Part 1 by James W. Waddick

The intent of this brief introduction to peonies is based on two
assumptions: 1) that this is an introduction to the whole genus and 2)
that garden peonies are not widely grown in western gardens. I'll follow
with some suggestions.

The genus Paeonia is primarily a temperate genus of plants
closely related to the Family Ranunculaceae, but now usually confined to
their own Family Paeoniaceae. In many ways peonies are horticulturally
treated as bulbs in the widest sense. Many have thick storage rots and a
life cycle based on spring flowering/fall planted bulbs. Some bulb
nurseries actually grow and sell dormant peonies along with the
traditional tulips, daffodils and hyacinths.

Horticulturally the genus is divided into two 'structural'
groups: herbaceous peonies and woody peonies. Systematically they are
best understood as four subgenera:

American Native Peonies (Subgenus Onaepia)

And in Part 2:Chinese Peonies (Subgenus Albiflora containing the
single species P. lactiflora)
Most Herbaceous Peonies (Subgenus Paeonia)

Native Species
Most gardeners, even West Coast Gardeners do not realize that
there is one (or two) species native to the US west coast. Paeonia
brownii ( or ssp brownii) is found in the Pacific Northwest in OR, WA,
ID, UT WY, NV mostly in high desert sites. The closely related, P. b.
ssp. californica (or P. californica) is found in a smaller area of
central and southern CA in desert sites. Both have attractive foliage,
but their dull maroon-brown flowers are hidden in the foliage and
generally attractive only to collectors. They have proven difficult to
grow outside their native area without extensive special care. I grow
mine on a high raised bed for increased drainage and no added water.
This species has the most bulb-like yearly cycle. In mild
climates the foliage emerges in fall at the onset of rains, remains all
winter to bloom in early spring and then goes dormant with spring/summer
heat and dry. P. b. californica is especially intolerant to heavy frost.

Woody Peonies
The cultivated tree peonies grow from 3 to 6 feet tall (certainly
not 'trees') and have long-lived, woody stems. There are two sub groups;
1) the shrubby stoloniferous P. delavayi species with red, yellow or
white flowers, and 2) the taller forms most often found in gardens
including P. suffruticosa, P. rockii and relatives. These have been
cultivated for centuries, perhaps a millennium, in China and in the West
for about 150 years.
Woody peonies comprise as few as 3 or 4 species or as many as 10
depending on your 'authority'. The arrangements are especially
controversial due to the long period these have been cultivated in China.
All are found in SW China and among the most southerly of all peonies. As
expected these will do well in milder climates and can be grown as far
south as Los Angeles with some understanding and proper care.
Tree peonies can reach to seven feet and live over 100 years. A
well-grown plant can have hundreds of flowers up to a foot across and
inspire growers to excess. They certainly deserve to be more widely grown
in many areas and microclimates on the Pacific Coast. They require a
minimum winter chill for dormancy and bud production. Some growers remove
still green foliage during the coolest season to encourage this dormancy.
These plants are the least bulb-like in growth, but can still be
dug and shipped bare-root when dormant in the fall like other bulbous
plants. In the ground treat them like woody shrubs.