Our plant of the season is none other than the Cornus kousa, Kousa dogwood, a Secrest Select tree. A cousin to our native eastern dogwood (Cornus florida), it blooms later in the season. The species is native to Taiwan, Korea, China, and Japan, where it acquired the species name kousa.
Cornus kousa is more cold hardy than Cornus florida, being hardy to USDA Zone 4b according to Michael Dirr. The tree, which matures between 20-30’ tall in landscapes, produces flowers in late May to June. “Flowers,” which consist of bracts, are white but selections like ‘Satomi’ and Scarlet Fire® have been bred to sport pink bracts. The true flowers are borne in a small, rounded umbel in the center of the bracts and are inconspicuous.
The edible, but mealy salmon-red fruit, is about 1” in diameter and adds to the ornamental appeal of the plant. I have found in my taste-tests in the arboretum that the flavor and texture of the fruit is highly variable from tree to tree and from year to year. Nonetheless, it provides a fun snack and talking point for various groups that visit the arboretum. While birds will eat the fruit, the primary animal to feast on them in Secrest is the chipmunk.
Cornus kousa has an upright habit when young, becoming vase shaped at maturity. Generally, the plant is considered slow growing, and according to North Carolina Extension Gardener Toolbox, is mildly resistant to deer damage. However, it is our experience that deer tend to rub on the trunks of young trees causing damage to the bark. As Cornus kousa ages, it develops beautiful bark which exfoliates in puzzle-piece-like chunks. In the fall, the leaves turn reddish purple and persist for three to five weeks.
You can grow Cornus kousa in full sun, but it does best with a little afternoon shade. It is a disease resistant tree that thrives in average garden soil but prefers soils that are rich in organic matter and are moist but well-drained. You will not be disappointed adding one to your garden! You can find selections of Cornus kousa at Autumn Discovery Day on October 4.
--Paul Snyder, Operations Manager snyder1062@osu.edu