Summersweet (Clethra Alnifolia): A Choice Fragrant Shrub for Your Garden

Summersweet (Clethra alnifolia) appears to be a modest little garden shrub at first glance, but during midsummer, its blooms dazzle the senses with intoxicatingly heady sweet clove perfume. Summer will be sweet, indeed!

Clethra grows as a native in most of the Eastern United States. It is also known by the names sweetpepper bush, and coastal sweetpepper bush. In the wild, Clethra grows in wet coastal areas, damp spots and woodlands, but actually prospers in a variety of settings, sun or shade, and even tolerates salt spray. It is hardy in USDA zones 3 to 9, from Nova Scotia down to Texas. In nature, the shrub suckers and spreads slowly to form colonies, and can be 8' tall and 6' wide. It has few pest problems and, luckily, doesn't appeal much to deer.

Native plants are always desirable in the garden because we know they thrive in our local conditions. At times they might appear a little too wild or rangy for some gardeners' tastes, and invariable, hybridizers refine their characteristics to increase their commercial appeal. This is the case with Clethra. The natural form has white bottlebrush shaped flowers, which sometimes have a pinkish tint. Cultivated garden varieties offer much deeper pink flower color. In some of the older varieties, they fade a little to white, but newer ones stay deep rose. The North Carolina State University website offers informative Plant Fact Sheets with a table listing some good cultivars with their sizes and characteristics. This site offers good pictures, also.

In my many years working as a garden designer, I used Clethra in a large number of gardens and always got a delighted reaction from my clients when it bloomed.

One important goal of garden design involves allocating available space wisely by picking plants that will offer appeal in multiple seasons. I think my clients sometimes wondered at first why I elected to plant little groups of Clethra, but when it bloomed, they understood. In spring, Clethra is late to leaf out, and admittedly, isn't anything special. As summer progresses, many of the famous fragrant bloomers, like lilacs, put on their show and finish, then in July and August, Clethra fills the air with its incredible perfume. After the flowering is done, small seedpods form, and in October, the leaves turn bright, clear yellow, and eventually drop, leaving the seedpods over winter.

If I were to select plants for a very small space, the taller, wider varieties of Clethra might not be worthwhile simply because three weeks of fragrant bloom and some fall leaf color isn't enough payoff to justify taking up that much space. I usually relied on Clethra a. "Hummingbird", a small shrub 2 ½' to 3' tall and equally wide. A group of three C. a. "Hummingbird" can be tucked into a nook near a garden bench and I'll guarantee you'll consider the space well used.

Sources:
personal experience

NC State University Plant Fact Sheet on Clethra