Featuring: Cornus kousa
Common name: Kousa Dogwood

by Rick Los, Director of Horticulture

Cornus kousa or the Kousa Dogwood is native to Japan and Korea and is one of the showiest of all summer blooming trees in our garden. The variety ‘chinensis' from China is very closely related and even experts have difficulty in distinguishing them from the typical species.

When we think of flowering Dogwood trees in this part of the world we generally think of the native Western Flowering Dogwood or Cornus nutallii. This tree is the official provincial flower of British Columbia and is a beautiful tree in its own right. However, although this is an outstanding tree with some beautiful ornamental features, I must give the nod to the Cornus kousa as the superior landscape tree. Cornus kousa blooms for a longer period (up to 6 weeks) and is relatively pest and disease resistant whereas

Cornus nutallii frequently suffers from anthracnose, a disease causing dieback on branches and often kills the tree. 

The most outstanding feature of the Cornus kousa is the amazing white bracts completely cover the tree and causing it to look like a brilliant white cloud. As the tree gets older the branches tend to become horizontally layered and this adds to the beautiful cloud-like effect. The tree begins to flower for us in early June and produces an interesting light red fruit; similar to a raspberry, early in the fall.

Cornus kousa is typically multi-stemmed and can be pruned at an early stage to a form you personally find desirable, as well as to show off the exfoliating bark which becomes a feature as the tree gets older. This is not a large tree as the typical mature size and spread is around 6 m. x 6 m. (20 ft. by 20 ft.), although there have been reports of the trees reaching 9 m. (30 ft.) tall. At The Gardens we have a beautiful specimen in one of our Rhododendron groves measuring close to 6 m. (20 ft.) tall with a spread of at least 7.6 m. (25 ft.).

As is the case with all Dogwood trees, Cornus kousa prefers to be planted in a well draining, fertile soil in partial shade or even full sun - although I would have to say the trees do perform better when they are not fully exposed to the sun all day long. The only issue we have had with these trees is ensuring they do receive additional water during warm and dry spells in the summer as the leaves may curl and even drop if this is not provided.

This tree has many great qualities throughout the year, but the glow of the brilliant white bracts will surely attract your attention when you visit the Gardens in June or early July.