Mystery dogwood

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on May 11, 2009 at 7:31 AM, updated May 11, 2009 at 7:37 AM
An American "flowering" dogwood in bloom.
Q: I went to a plant sale and got some free plants and trees that a local Girl Scout troop was giving away. They told me the trees were "flowering dogwoods." Aren't all dogwoods flowering? They didn't know what variety, but I was told they are the native ones. I don't want to plant them in my yard until I know what kind they are.

A: Yeah, all dogwoods flower, but I'll bet your dogwood is a native American dogwood (Cornus florida). This is the most common type and is typically called "flowering dogwood" (which is a bit like saying "wet rain.")

American dogwoods bloom pink or white from late April into early May and get oval red fruits in fall along with brilliant red fall foliage. It's a small tree usually found as an understory tree in nature or growing along the edge of a woods line. Birds love it.

On the down side, American dogwoods aren't very drought-tolerant, and they really don't like the clay, alkaline soil in full sun where home gardeners tend to plant them. That's almost exactly opposite of the cool, damp, acidy, humus-rich, well drained woodsy soil where they naturally congregate.

American dogwoods also run into several serious problems in the landscape beyond suffocating clay. They're prone to two leaf diseases (anthracnose and powdery mildew) and a potentially killer bug called dogwood borers, which tunnel into the wood and feed on the crucial cambium layer.

I like the kousa or Chinese dogwood (Cornus kousa) and the Rutgers hybrid dogwoods (Cornus x rutgersensis, a cross between American and Kousa) because they're much more disease- and borer-resistant and hardier in drought and clay soil. 'Saturn,' 'Galaxy', 'Aurora' and 'Stellar Pink' are examples of Rutgers hybrids. 'Milky Way,' 'Greensleeves' and 'Moonbeam' are some of the best kousa varieties.

I also like the pagoda dogwood (Cornus alternifolia, another American native with a more horizontal growth habit and bluish-black fruits) and the cornelian cherry dogwood (Cornus mas, a European type with early-spring yellow flowers and red fall fruits).