Kousa dogwood (Cornus kousa)
Cornus kousa (Kousa dogwood) is one of a few, terrific landscape plants that have multi-seasonal appeal. It could be Plant of the Month for June, when it flowers. The white to creamy-white inflorescence, or “flower”, held above deep green 2-2 ½ inch leaves, is comprised of four white bracts that many people think are the “petals”. Each individual bract is about 1-2 inches long and approximately ¼ to ¾ inches wide. The four bracts surround the “true” small, almost inconspicuous, green–yellow flowers produced in an umbel in the center of the four white bracts, which usually persist for six weeks and sometimes even longer. Pollinators, like bees and butterflies, are attracted to the small flowers and, after pollinating them, a round green fruit (drupe) begins to form on a 2 to 2 ½ inch long pendulous stalk.
The round green fruit develops into a round, spherical raspberry-like, deep pink-red fruit that begins to color up in late August – early September and often persists into October. The fruit, while mealy and not very palatable, is edible and is also attractive to wildlife (birds, squirrels, etc). A showy display of these pink-red fruits dangling from the branches on the Kousa dogwood adds color and decorative visual interest to the September landscape, making it a good choice for Plant of the Month for September.
In autumn, the medium-dark green foliage gives way to a deep red-burgundy fall color, and, on older, more mature trees, after the leaves fall, a beautiful, mottled, exfoliating bark of tans, browns and grays can be seen, adding interest to the late fall, winter and early spring landscapes.
Cornus kousa is a small to medium (20 to 35 feet high with equal width), vase- shaped deciduous tree, native to China, Korea and Japan. It is a tree with no significant insect or disease problems. It is resistant to dogwood borer and dogwood anthracnose and, for those reasons, it is often planted as an alternative to our native Flowering dogwood, Cornus florida. Cornus kouse is also more drought tolerant than the native C. florida. Kousa dogwood may be planted in small groups, used as a specimen plant, or as a lawn plant, in a mixed shrub border, etc. However, be aware that it will drop its decorative fruit, so avoid planting this tree near a driveway or other areas where the fruit would become messy or become a maintenance problem.
Kousa dogwood grows best in an organic, well-drained, moisture-retentive soil, in full sun (6 or more hours), but will tolerate some light shade. It is winter hardy to Zone 5 and is an excellent low-maintenance, sustainable tree that provides landscape interest throughout the year.
There are numerous, perhaps 100 or more, Cornus kousa cultivars available, including some like ‘Benji Fuji’ or ‘Satomi’ with bright pink bracts. There are cultivars with green and white variegated foliage like ‘Wolf Eyes’ and ‘Samzan’ (Samaritan®); or cultivars with green foliage with a gold center (‘Gold Star’). There are weeping forms like ‘Elizabeth Lustgarten', ‘Lustgarten Weeping’, and ‘Weaver’s Weeping’, which may grow to a height of 12 to 15 feet and display downward arching branches covered in cascading white flowers in June.
Cornus kousa – a great plant for September as well as many other months; so many cultivars, so little time.
Deborah C. Swanson, Horticulturist