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Summersweet

Summer heat and humidity cause folks to think about escaping to swimming pools, lakes, mountain retreats, and beaches. If your home is your sanctuary, then find refuge in your garden with our native summersweet (Clethra alnifolia). This month, summersweet produces spikes of spicy, fragrant flowers atop a 4 to 8 ft. high multistemmed shrub with attractive lustrous green leaves. The flowers mature into clusters of woody capsules that look like dried peppercorns. In the fall, summersweet leaves turn pale yellow to rich golden yellow.

Despite its small stature, Hummingbird summersweet produces more flowers than the species to the delight of people and pollinators. Bob Polomski, ©2021, Clemson Extension

Despite its small stature, Hummingbird summersweet (Clethra alnifolia) produces more flowers than the species to the delight of people and pollinators.
Bob Polomski, ©2021, Clemson Extension

For you and me, summersweet is a visual and olfactory delight. To butterflies and other pollinating insects, it’s a smorgasbord of nectar and pollen. While you can settle for growing the straight species, take a closer look at an extensive menu of desirable cultivars available. ‘Hummingbird’ is a compact, 3 to 4 ft. high white-flowering gem that tends to flower more heavily than other named cultivars. ‘Sixteen Candles’ is a selection that bears 4- to 6-inch long arrow-straight spikes of white flowers that look like birthday candles. And, ‘Sherry Sue’ is a cultivar that offers multi-season interest: white flowers in midsummer, golden fall-colored leaves, and brightly colored red stems in winter and early spring. You want pink? ‘Ruby Spice’ will take you to your “happy place” with rose-pink flowers.

Hummingbird summersweet planted in drifts or en masse results in a spectacular display of fragrant flowers. Bob Polomski, ©2021, Clemson Extension

Hummingbird summersweet planted in drifts or en masse results in a spectacular display of fragrant flowers.
Bob Polomski, ©2021, Clemson Extension

Despite the differences in flower size and color between the straight species and the cultivars (or nativars, in this case, which is a native cultivar), pollinators find them equally appealing. In a 2019 study, University of Connecticut scientists found similar numbers of pollinators visiting the flowers of summersweet and its cultivars, Hummingbird and Ruby Spice.

Summersweet grows in partial shade to full sun, but from my experience, shade from the afternoon sun keeps it looking its best, provided that you water during very dry spells. Use this multistemmed shrub in mixed borders, damp areas, rain gardens, bogs, or in naturalized areas along streams and ponds.

Ruby Spice produces rose-pink flowers on a 3 to 4 ft. tall shrub. Bob Polomski, ©2021, Clemson Extension

Ruby Spice produces rose-pink flowers on a 3 to 4 ft. tall shrub.
Bob Polomski, ©2021, Clemson Extension

Yes, I am smitten by this native shrub, which forces me to end with this cheesy line: Summer will never be as sweet without summersweet.

Source:

  1. Ricker, J. G., J. D. Lubell, and M. H. Brand. 2019. Comparing insect pollinator visitation for six native shrub species and their cultivars. HortScience 54 (11):2086–2090

If this document didn’t answer your questions, please contact HGIC at hgic@clemson.edu or 1-888-656-9988.

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