Fall color on a Sargent’s cherry at the north end of Azalea Way. (Photo by Niall Dunne)
BY PHIL WOOD
Azalea Way is famed for the wonderful spring floral display of its cherry trees, many of which date back to the early, formative years of Washington Park Arboretum. Less well known is the brilliant fall color that some of these trees produce.
Take the Sargent’s cherry, Prunus sargentii, for instance. In late March and early April, the tree bears copious clusters of beautiful, single, blush-pink flowers before its shiny, oval, dark-green serrated foliage emerges. In October, the leaves turn a stunning orange to bronzy red before dropping.
Native to northern Japan and Korea, Prunus sargentii grows up to 80 feet tall in the wild but usually ranges between 20 and 40 feet tall in culti-vation. As it matures, it develops a broad, rounded crown. The flowers develop into small, sour, black cherries, which disappear quickly from the branches, due to their popularity among birds.
Another attractive feature of the tree is its bark: shiny, reddish-brown, with prominent horizontal lenticels (pores, for gas exchange). The bark can roughen with age, but it retains its color and banded patterning.
‘Pink Flair’ Sargent’s cherry blooming in early April. (Photo by Niall Dunne)
Azalea Way Legacy
The species name honors American botanist Charles Sprague Sargent (1841–1927), first director of Harvard’s Arnold Arboretum. Prunus sargentii was introduced to the U.S. in 1890, when surgeon and Japanese art collector William Bigelow (a Harvard graduate) sent seeds to the Arnold Arboretum. Sargent also collected seeds during an expedition he made to Japan two years later, and he was instrumental in distributing the tree to other botanic gardens.
Our Arboretum has about a dozen Sargent’s cherries strewn along the length of Azalea Way. The eldest of these date to 1940 and were acquired in a large batch from Princeton Nursery, New Jersey. A few of them are still going strong—such as the wonderful 35-foot specimen growing directly across the promenade from the Hybrid Rhododendron Garden—while others are reaching the end of their life spans.
Because of our rainy climate, it can be tough to grow cherry trees in the maritime Pacific Northwest. A number of fungal diseases—in particular cherry blossom brown rot—and insect pests can wreak havoc with ornamental Prunus varieties. However, Prunus sargentii is one of the better cherry options for our region.
“Generally, Prunus sargentii is much more disease resistant than Prunus subhirtella or Prunus serrulata,” says Ray Larson, assistant director and curator of UW Botanic Gardens. “While resistant to cherry blossom brown rot, it still can get cherry bark tortix. Generally, we’re lucky to get 60 years out of a cherry in the Pacific Northwest, so anything above 80 is very good indeed!”
Close up of the flowers of ‘Pink Flair’. (Photo by Niall Dunne)
Culivated Varieties
Several cultivars of Sargent’s cherry are available, include ‘Columnaris’ and ‘Rancho’, both more upright than the straight species. In recent years, the Arboretum has been planting ‘Pink Flair’, which is both more upright and more compact than the straight species, topping out at 25 feet high.
‘Pink Flair’ was developed by the nursery J. Frank Schmidt & Son, of Boring, Oregon. On their website, they say the cultivar avoids frost damage by flowering a week or two later than is typical of the species.
My favorite ‘Pink Flair’ specimen in the Arboretum grows beside the large western red cedar at the north entrance of Azalea Way. Dating to 2014, it has already grown to about 20 feet in height. It is striking in spring bloom and fall color—a beautiful beacon welcoming visitors into the park from the Graham Visitors Center.
When selecting a cherry for smaller home gardens, size is an important consideration, so Prunus sargentii ‘Pink Flair’ is a good candidate. Like the straight species, it is resistant to fungal disease. It’s also on the Arboretum’s checklist of recommended cherries for the Pacific Northwest. (See “Disease-Resistant Cherries for the PNW” below.)
Attractive, striped bark on a mature specimen of Sargent’s cherry on Azalea Way. (Photo by Niall Dunne)
Growing Tips
Providing good light and soil conditions are also key for growing cherry trees in our region. As with other cherries, Prunus sargentii does best in full sun and medium-moist, well-drained soils.
“The Arboretum’s clay soils along Azalea Way can make siting of new cherry trees a challenge at times,” says Ray. Annual mulching around the base of your tree with arborist wood chips will not only improve poor soil conditions but also help suppress fungal pathogens that might be living on fallen leaves and other debris.
If you’re looking to plant a cherry, you can’t go too far wrong with Prunus sargentii. It offers stunning spring bloom, food for local wildlife, lovely bark, and a bonus of vibrant fall color.
Phil Wood is a retired garden designer and a member of the “Bulletin” Editorial Board.
Disease-Resistant Cherries for the PNW
In a 2018 blog post on the UW Botanic Gardens website, then-horticulture man-ager David Zuckerman wrote about the pest management techniques used in the Arboretum to care for the flowering cherry collection. It specifically addressed techniques for battling the cherry blossom brown rot fungal disease, which include pruning to remove infected twigs and improve air circulation, and adding a fresh ring of wood chip mulch around trees in the fall to bury any infected plant material that may be on the ground. Another practice is to replace dying or dead trees with cultivars that are known to be resistant to the brown rot fungus. David attached a list of resistant cultivars that the horticulture team uses at the Arboretum:
Prunus ‘Berry Cascade Snow’
Prunus ‘Kwanzan’ syn. ‘Sekiyama’
Prunus sargentii ‘Pink Flair’
Prunus ‘Royal Burgundy’
Prunus ‘Shirofugen’
Prunus ‘Shirotae’
Prunus ‘Snow Goose’
Prunus subhirtella var. ascendens
Prunus × yedoensis ‘Shidare Yoshino’
Source: “Flowering Cherries Need to Stay Healthy,” by David Zuckerman. UW Botanic Gardens Blog. March 16, 2018. ❦
Subscribe to Our Bulletin Magazine!
This article is reprinted from the fall 2025 issue of the Arboretum Bulletin, our quarterly botanical and horticultural magazine. Published since 1937, the Bulletin is a benefit of Arboretum Foundation membership and features in-depth articles on the Arboretum collections and history, as well as general information of interest to plant lovers in the Pacific Northwest and beyond. Join/subscribe today.
