Summersweet (Clethra alnifolia 'Sixteen Candles') is a deciduous shrub native to the swampy woodlands and coastal marshes from Maine to Texas, prized for its intensely fragrant white flowers that bloom from July through August. Growing 4 to 5 feet tall and 2 to 3 feet wide, it thrives in zones 4 through 9 and tolerates everything from wet soils to heavy shade, making it nearly foolproof for damp spots where other shrubs struggle. The flowers appear in narrow, upright spikes that attract butterflies and other pollinators throughout the summer, filling the garden with a sweet fragrance that lingers into evening.
Partial Sun
Moderate
4-9
60in H x 36in W
—
Moderate
Hover over chart points for details
The fragrant flowers emerge in midsummer, exactly when many gardens are fading, and they rise in slender spikes that look almost like candles against the green foliage. This shrub genuinely thrives in wet, boggy soils where most ornamentals would rot, which makes it essential for rain gardens and areas prone to standing water. Its low maintenance requirements and ability to tolerate everything from full sun to dense shade mean you can place it almost anywhere on your property and it will perform beautifully.
Summersweet serves as an excellent foundation shrub for rain gardens and wet areas where it stabilizes soil and prevents erosion. Its fragrant summer flowers and pollinator-attracting qualities make it valuable in conservation gardens and native plantings. The shrub works well as a specimen plant in woodland borders, along stream banks, or in any landscape where moisture lingers rather than drains quickly.
No timeline data available yet for this variety.
Germinate seeds at 65 to 75 degrees Fahrenheit if starting from seed, though cuttings are the preferred propagation method for this cultivar.
Prune in late winter if needed to maintain shape or remove dead wood. The shrub naturally grows in a rounded, densely-branched form, so pruning is largely optional unless you wish to control its spread or remove the root suckers that may appear at the base. If a more naturalized, suckering appearance suits your landscape design, leave pruning to a minimum.
Enter your ZIP code to see a personalized growing calendar for this plant.
“Clethra alnifolia has been documented as a native plant across eastern North American wetlands for centuries, growing in the wild from Maine down the Atlantic coast to Florida and west into Texas. The species became popular in cultivation during the Victorian era when gardeners began collecting native plants and breeding ornamental forms. 'Sixteen Candles' represents a modern cultivar selection, bred to enhance the ornamental qualities of the species, particularly the upright flower spikes that justify its common name.”