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Plants from the Ground Up

Clethra the Fragrant Beauty of Summer

Clethra is one of my true plant loves! Aptly called Summersweet due to its deliciously spicy-sweet summer flowers. We call it the ‘rootbeer’ plant here at the nursery since its fragrance reminds us all of that tasty brew. The pretty white (sometimes pink) flowers appear in July and August when not much else is blooming. They have an extra superpower, they will even flower in the shade! ‘Clethra’ comes from the Greek klethra, meaning Alder, since their leaves somewhat resemble those of the Alder tree.

Clethra alnifolia Sixteen Candles - White Summersweet

Clethra alnifolia Sixteen Candles – White Summersweet

Clethra alnifolia: Summersweet or Sweet Pepperbush

These small 3′ to 6′ shrubs are native to the moist creeks, marshes or shorelines of the eastern United states. They are found from Maine to Florida and across to Texas. One of the best things about Clethra alnifolia is that it is so easily grown. Thought it prefers moist, acidic soils and partial shade, it will survive in full sun to heavy shade and tolerates sandy to clay conditions. This shrub tends to be rounded in form and the leaves are a rich dark-green. The upright flower panicles are usually white, however, ‘Ruby Spice’ offers variety with its beautiful dark-pink flowers. The fragrant blooms send their powerful fragrance all through the garden and are much loved by hummingbirds and butterflies. Summer flowers give way to persistent brown seed capsules which look pretty when contrasting the golden-brown fall color; peeling grey-brown bark in winter is also appealing. Summersweet is a perfect shrub for mass plantings or rain gardens. Clethra alnifolia is hardy to USDA zone 4.

Clethra alnifolia Ruby Spice - Pink Summersweet

Clethra alnifolia Ruby Spice – Pink Summersweet

Clethra acuminata: Cinnamonbark, Mountain Pepperbush or Summersweet!

Another lovely American Summersweet from the woodlands and riverbanks of the Appalachian region. This species is much larger than its cousin alnifolia and can reach 6-12 feet. Cinnamonbark has lovely white fragrant flowers and unique cinnamon-colored peeling bark. Its growing requirements are much the same as Clethra alnifolia. Another reason to plant this species is that it is disappearing in the wild, it is officially listed as endangered in Pennsylvania. Clethra acuminata is hardy to USDA zone 6.

Clethra acuminata - Summersweet

Clethra acuminata – Summersweet

Clethra barbinervis: Japanese Summersweet

From the woodlands and streams of Japan comes another gorgeous Summersweet. Larger than its American relatives, Japanese Summersweet can reach upwards of 20 feet. This species can take the form of a shrub or small tree. The white summer flowers are not quite as fragrant as other species, but they hang down in more horizontal or weeping fashion that has a very graceful look.  Japanese Summersweet has very striking gray exfoliating bark that gives it unique winter interest. Japanese Summersweet makes a beautiful specimen plant and can also be used massed along ponds. Clethra barbinervis is hardy to USDA zone 5

Clethra barbinervis - Japanese Summersweet

Clethra barbinervis – Japanese Summersweet

All Summersweet provide four season interest, attract birds and butterflies, have wonderful fragrance, are easy to grow, and are deer resistant. There is certainly room for one of these delightful shrubs in every garden. These shrubs tend to sucker, but the bottom shoots can be removed it you prefer a more manicured looking shrub. Clethra can be grown from seed sown in spring or autumn and also by greenwood cuttings in summer. 

For more photos and information, see Clethra at the Forestfarm Store.

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