The Garden Guy has known of the summersweet or Clethra alnifolia for over 20 years; when the variety Hummingbird was selected as a Georgia Gold Medal Winner in 1996. If I may pose the question, however, do you, 'really' know it? Embarrassingly I have to admit, I didn't.
I am here to tell you it is a champion of pollinators. I have been watching for weeks and witnessing a spectacle of nature. There are more bee and wasp species than I knew existed buzzing around in a state of pure ecstasy.
You will notice, that is not all, hummingbirds will feast as will the Eastern Tiger Swallowtail, American Lady, Gray Hairstreak, Red-banded Hairstreak, Silver-spotted Skippers, and more. The native clethra or summersweet is an entomological treasure chest.
The bottlebrush-like spikes are an exotic beauty as well. It looks as though it was created to be partnered with Virginia sweetspire, but forms an idyllic combination with purple-leafed plants like Purple Pixie or Purple Daydream loropetalum. You'll also love it with white blooming hydrangeas.
The blooms of the summersweet yield a fragrance as luring as the finest of perfumes. Growing a bold drift or sweep of these shrubs around the porch patio or deck will give the family, and all who visit, an olfactory experience in which memories will be created. Can you imagine a native plant offering so much in June and July?
The pure native would make a fine choice for your landscape, but there are reasons others have been made for the market place. Hummingbird was selected for its uniformity and compactness. It reaches 3 feet tall and 4 feet wide. It does sucker some but is easy to manage in allotted space. Sixteen Candles is also compact and holds blooms erect.
Ruby Spice is taller reaching 3 to 6 feet tall producing rose-pink blooms. It is known to sucker but is densely branched and makes a nice hedge. Vanilla Spice is large in habit and bloom. The plants will reach 6 feet tall and as wide with blooms reportedly twice as large as other selections.
Summersweets are tolerant of wet soil and resist browsing by deer. They offer good yellow fall leaf color before dropping leaves and the remaining seed capsules or fruit are eaten by a variety of birds. This gorgeous clump-forming native shrub is disease and insect resistant.
As mentioned, it can spread or form additional clumps by spreading underground stems. It is not hard to keep in bounds or maintained. Pruning will help you develop the desired bushy or mounding shrub look versus a thicket or briar appearance. They bloom on new wood so losing blooms to late frost is typically not an issue.
The ideal location would be in a naturalistic area where they receive morning sun and afternoon shade or high shifting filtered light. The clethra is a light feeder, the best time to fertilize is late winter with a slow-release balanced fertilizer spread evenly under mature plants.
Despite its native stature and compatibility over a large geographic area, plus all of the named selections, simply walking into your favorite garden center and picking up five may be a challenge. To be honest container-grown, nursery-stock can be planted just about any time, so take advantage and buy them when you see them for sale. Once you start growing the clethra or summersweet, you'll never want to be without some in the landscape.
(Norman Winter, horticulturist, garden speaker and author of, "Tough-as-Nails Flowers for the South" and "Captivating Combinations: Color and Style in the Garden." Follow him on Facebook @NormanWinterTheGardenGuy.)
(c)2019 Norman Winter
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