A native shrub that you should see this season is summersweet clethra (Clethra alnifolia). This species is native to the eastern United States, primarily the Coastal Plain from the New England states to Louisiana.
This deciduous shrub grows 4-6’ tall in a rounded habit but many cultivated selections are more dwarf. It is quite an adaptable plant, growing in water-filled ditches in its native environment, to being tolerant of drier conditions (though it is not recommended to plant this shrub in very dry locations). It also tolerates a variety of soil conditions from alkaline to acidic and is even tolerant of road salt.
While primarily a green shrub, its season of interest is summer (August) when the intensely fragrant flowers are born. The flower spikes are typically 4-6” long and composed of many small white flowers. It is a fantastic pollinator, supporting many species. Fall color can be a nice golden.
A few of the many cultivated selections include:
- Hummingbird (Clethra alnifolia ’Hummingbird’) which is more compact than the species at 2-3’ tall with large white flowers that open earlier than the wild form.
- Ruby Spice (Clethra alnifolia ‘Ruby Spice’) with typical 4-6’ tall size but rosy-pink flowers.
- Sixteen Candles (Clethra alnifolia ‘Sixteen Candles’) is another floriferous compact choice with a bloom on nearly every stem.
The Dawes Arboretum features 12 different named selections of this species and its closely related variety, Clethra alnifolia var. tomentosa (woolly summersweet clethra). Visit The Dawes Arboretum Explorer website and search for “Clethra” to see where they can be found on our grounds and get an up-close personal treat while these summer sweeties are still blooming!