Rhamnus (Buckthorn/Coffeeberry)

The genus Rhamnus includes about 125 species, but only two are grown with frequency in Sonoma County gardens: Rhamnus alaternus, Italian buckthorn, and the local native Rhamnus californica, coffeeberry. Many, but not all nurseries are now labeling some Rhamnus plants as Frangula.

Similarities and Differences

These two species are fully evergreen, require little water once established, and grow in full sun or partial shade, but they have completely different looks and growth habits.

• Both can be used as a screen or wide hedge or in a habitat shrub border.
• Both have flowers insignificant to gardeners but are highly favored by various pollinators.
• Both make a striking specimen when planted individually where there is ample space all around. Some varieties have showy berries in autumn. 
• These two species are amenable to pruning for controlling size and structure and can be elegantly shaped or left in their natural forms.
• When given plenty of space, they provide a backdrop for flowers and perennials as well as adding year-round interest to gardens.
• They remain green and lush through dry summers and cool, wet winters.
• As a bonus, they are relatively free of pest and disease problems and are unattractive to deer.

Italian Buckthorn, Rhamnus alaternus

• This very large shrub is slow to get started. It takes a few years to fill out and develop girth.
• The mature size is approximately 15 ft. tall and wide—or larger. It does not fit into a small space. It’s important to keep these numbers in mind at planting time when the shrub is small so that it is sited in an amenable place.
  • A five-gallon-size nursery plant is usually the most satisfying size to purchase.
  • Where space allows, generally on a large property, a substantial row of several makes a very imposing privacy screen or windbreak.
  • Once pruning begins to control size, it becomes a never ending—and frequent—process to rein in annual growth. Long-term pruning is not advised.
  • Gardeners who have attempted a pruning strategy either end up hiring a professional to maintain the growth or eventually remove the shrub altogether.
• The plain species, Rhamnus alaternus, bears glossy, small, deep green pointed leaves. 
  • Rhamnus alaternus‘Variegata’ foliage has cream margins and deep green centers, beautiful markings sought after for informal floral arrangements.
  • The structure and shape of the plant is the same as its green cousin but the leaf variegation results in an overall very light-colored shrub, a somewhat rare element in landscape shrubs.
  • ‘Variegata’ is especially striking when planted against a darker background. 

Coffeeberry, Rhamnus californica

This is a very different shrub from Rhamnus alaternus although its cultural requirements are essentially the same.

• As the name suggests, this species is native to California and is found primarily in coastal regions as far north as southern Oregon.
• Most nurseries continue to use the Rhamnus label although most botanists have made the change to Frangula.
• Compared to Italian buckthorn, coffeeberry leaves are much darker and larger—nearly 3 in. long—rounder, and somewhat leathery with pale undersides.
• Berries decorate plants for several months as they ripen from pale green to orange-red to burgundy before turning black and eaten by birds and small animals.
• Species plants found in the wild grow larger and lankier, some reaching over 12 ft. tall, compared to most of the named cultivars which are more appropriate to home gardens.
  • ‘Mound San Bruno’ grows to about a 5 ft. height and width and features light green leaves and a dense form. It is considered to be the most adaptable coffeeberry for gardens.
  • ‘Eve Case’ is sought after for its attractive large, showy berries and its 5-10 ft. size, key for including in a habitat shrub border. In hot, inland areas, some afternoon shade may be needed to prevent leaf burn.
    • ‘Eve Case’ leaves are a bit larger, darker, and coarser than ‘Mound San Bruno,’ but is equally attractive.
    • It is not quite as amenable to shaping, however, as is ‘Mound San Bruno’ and is best planted only in spots that are able to accommodate the mature size.
    • In contrast, ‘Seaview’ rambles as a groundcover under 2 ft., spreading wider to 6-8 ft.
  • Another variety with distinctive berries, ‘Leatherleaf,’ is smaller than ‘Eve Case’ and a better choice for smaller gardens. It tops out around 5-6 ft. and has darker foliage with leaves that may reach 4-6 in. long.
  • Several other cultivars are offered at native plant nurseries.
    ‘Jelly Belly’ is a fairly new small selection.

September 2023