Updated: Mar 8, 2022
Name: Clethra alnifolia - Sweet Pepperbush or Summersweet
Bloom Time: July - August
Flowers: White spikes occasionally with a touch of blush pink
Soil Condition: Prefers moist soil. Tolerates clay, wet, salty, sandy. Do not let dry out.
Light: Full Sun, Partial Shade, Shade (Flowers best in full sun and partial shade)
Height and Width: 3-8' x 4-8'
Native Range: Eastern and Southern North America
Clethra alnifolia is one of my absolute favorite native shrubs. When most shrubs are done flowering, C. alnifolia is just getting started. The blooms are intoxicatingly sweet with a hint of spice and the nectar attracts an abundance of butterflies and bees. At home in the woodland garden as well as a foundation plant, specimen or hedge. Wherever you decide to plant C. alnifolia, make sure it's a place where you can enjoy the fragrant flowers. To top it off, the fall foliage is a lovely yellow and bright brown. Makes a great alternative to the invasive Buddeia davidii (Butterfly Bush).
Maintenance: Very low maintenance plant. Blooms on new growth. Prune in late winter. Will need supplemental water during droughts. Remove root suckers to control spread.
Benefits: Attracts birds, butterflies and hummingbirds. Songbirds are attracted to the seed capsule
Conditions Comments: Excellent for coastal gardens due to salt-spray tolerance.
Propagation: clump division, root division, seeds (no pretreatment necessary, sow seed on sand), softwood cuttings
Maintenance: very low maintenance, prune/shape in late winter, will need supplemental water during long drought periods
Growth Rate: slow to moderate
Companion Plants: Lobelia cardinals (Cardinal Flower), Tiarella cordifolia (Foamflower), Chelone glabra (White Turtlehead), Aster cordifolius (Blue Wood Aster), Caltha palustris (Marsh Marigold), Carex albicans (White-tinged Sedge)
Cultivars: 'Ruby Spice': All the same attributes but shorter than the straight species at 4-6' tall by 3-5' wide. Rose pink flowers instead of white. Tends to be a little floppy unlike the very vertical presence of the straight species. See center picture above with an Eastern Tiger Swallowtail Butterfly.