One summer day working at a client’s garden doing routine maintenance, I caught a whiff of wonderful fragrance on the breeze. After searching for the source, I came upon a mid-sized shrub full of narrow, spike-like creamy white flowers with an extremely sweet fragrance. Alive with insects darting in and out, the shrub swayed in a slight breeze wafting fragrance. That was my first experience seeing a Summersweet, Clethra alnifolia, at its peak of bloom and fragrance, and it left a lasting impression with me. Clethra is one of the best shrubs for mid to late summer color and fragrance.
Clethra has lots of other reasons to grow besides the knock-out fragrance and the beautiful abundant flowers. The yellow fall color is a standout and the shrubs shine with a clear yellow light, even on a cloudy day.
Glossy dark green leaves with exfoliating brown bark makes this a complete multi-seasonal interest package. The fragrant flowers are followed by brown capsules, which attract small mammals and birds. A tall (6-10′), many branched, deciduous shrub, clethra often spreads into mounded clumps, spreading by suckers that pop up nearby.
There are dwarf forms, notably Sugartina from Proven Winners and these look good planted in a group.
Easily grown in average, medium to wet soils in full sun to part shade, Clethra is a valuable plant for wet situations where many other shrubs would die. it tolerates clay soils and full shade as well. Sending out suckers or runners, you can easily remove these unless you want it to naturalize and spread in a large area.
Prune if needed in late winter to shape the shrub, but many times, I leave it alone. Since the shrub blooms on new growth, pruning can be done without any harm to the future flowering. Sometimes after a harsh winter, pruning is a good way to rejuvenate the shrub, removing any old or weakened branches. Clethra tolerates occasional flooding, actually thriving in wet soil, which makes this a perfect rain garden plant.
Native from Maine to Florida and west to Texas, it is found in the wild in mashes, stream banks, and along seashores. Flowering in mid to late summer, when most shrubs are done, the flowers are like magnets for butterflies, hummingbirds, and bumblebees, honey bees, and other native bees – a huge draw! Even in shade, Clethra will flower profusely, so it is a great native for woodland gardens. I like to group the shrubs in borders for dramatic impact.
After I designed a healing labyrinth for a client, I surrounded it with Clethras which light up the entire area in the fall with their yellow color. Rarely bothered by deer and not troubled with disease or insects, this is an extremely versatile native shrub. Noted plantsman Michael Dirr says of this plant, “This is one of my favorite shrubs and the more I work with it, the greater my appreciation for its user-friendly nature”.
