The last of the dogwood blossoms are still gracing gardens around the area. The Eastern dogwoods started blooming in late April and have been putting on a show ever since. The Kousa dogwoods are just finishing as I write this.
The most popular dogwoods found in gardens here are the pink-flowering Eastern or Florida dogwoods (Cornus florida) that are native to the forests of the Eastern U.S.
Dogwoods are noted for their interesting horizontal branch structure. The tree holds its leaves in tight curved clusters along the top of the branch, adding to the textural interest, especially when the wind shows off the grayish white underside of the leaves. In the fall, they turn subtle but striking shades of red and burgundy. The trees can grow to 20 feet high and wide.
The flowers bloom from white to light pink to almost a red, depending on the cultivar. One of the reasons they are so stunning is the tree blooms before the leaves come out so that flowers are all you see. But the “flowers” we see aren’t really flowers; they are modified leaves called bracts that surround the inconspicuous yellow flowers at the center of the bract cluster.
The trees need a well drained humus-rich soil and regular deep watering especially during the drier part of the summer. They can be planted in full sun away from walls and large rocks that tend to hold heat. They do exceptional well in morning sun and light afternoon shade. Trees planted in too much shade will grow more quickly but flower less. It can take several years for a young tree to begin blooming. Dogwoods do not need any pruning as they grow slowly and their natural shape is one of their hallmarks.
The Eastern dogwoods are at their hardiness limit here. Even then, that hardiness depends on where your tree was originally grown. Trees grown in the Southern U.S. are not as hardy as those grown in the colder northern areas. Avoid ordering trees from mail order sources based in the South. Better yet, shop at your local nursery and pick the tree yourself.
While Eastern dogwoods are popular, they have some issues. The Kousa or Japanese dogwood (Cornus kousa) may be a better choice here. Kousa dogwood is native to Korea and Japan with a growth habit and cultural needs similar to the Easterns. The tree is a little hardier than its American cousin and it blooms in late May to early June here, which helps it escape the late frosts that can damage the Eastern’s blooms.
The major advantage though is the Kousa dogwoods are much more resistant to a fungal disease called anthracnose. This disease deforms the leaves and can kill the tree. There are a number of Kousa cultivars available and breeders have crosses of the Eastern and Kousa that have better resistance.