Rhamnus – Beautiful Buckthorns for Almost Any Garden
By Sara Malone, Sonoma County Master Gardener
Regular readers of this site will have already heard me sing the praises of foliage over flowers, form over confusion. Thus, it comes as no surprise that I love rhamnus, commonly called buckthorn, in almost all of its species and varieties. However, those of you cottage garden fanciers will love rhamnus, too, because this is a genus that has lovely rich, glossy evergreen leaves (or in one case, beautifully variegated foliage), is amenable to pruning for size and structure, attracts numerous pollinators and in some varieties, sports showy berries in autumn. The elegantly shaped shrubs provide a perfect backdrop for flowers and perennials, as well as adding year-round interest to your garden. This is one low-water plant that stays green and lush all through our dry summers.
The genus rhamnus includes about 125 species, but only two are grown with frequency in the Bay Area: R. alaternus (Italian buckthorn) and R. californica, (coffeeberry). They have rather different looks and growth habits, but I love and use them both in my garden. These two species are fully evergreen, grow in full sun but are tolerant of shade, and require little water once established. As a bonus, they are relatively free of pest and disease problems. They can both be used as a screen or wide hedge, in a shrub border and make striking individual plantings. Both have insignificant flowers that are highly favored by various pollinators.
Italian buckthorn rhamnus alaternus
rhamnus alaternusRhamnus alaternus is an upright shrub native to the Mediterranean region, with extremely glossy, small, deep green pointed leaves. It is slow to get started (a five gallon is usually the most satisfying size to plant) but after a few years will take hold and fill out. Its mature size is approximately 15 feet tall by 5 feet wide, so this is not a small shrub; however, it can be pruned carefully to slow it down and keep it smaller. I generally like to prune it in winter as the cut boughs make a wonderful addition to holiday greenery arrangements and inside decorations. A row of r. alaternus makes a beautiful hedge, privacy screen or windbreak, and you can either place the plants in a straight line or stagger them for a slightly more natural look. The glossy foliage is decorative in itself, but as noted, it makes a beautiful backdrop for perennials, flowers or deciduous shrubs with showy blooms.
R. alaternus ‘variegata’, variegated Italian buckthorn, has variegated leaves instead of solid green ones. That is like saying that rose bushes have a flower; the variegated leaves on R. alaternus variegata are among the most beautiful leaves that I have ever seen. The structure and shape of the plant is the same as its green cousin, (although perhaps does not get quite as tall) but each leaf is gray-green with a conspicuous white margin, making the shrub very light-colored. To find a rhamnus alaternus variegatashrub this robust with this kind of coloring is rare. It is especially striking when planted against a dark-colored background, such as a group of r. alaternus! I have a mixed hedge of the two varieties, which I planted as a windbreak, and it is one of my favorite parts of my garden. R. alaternus variegata has the added feature of tiny flowers whose stems turn reddish in fall and winter. This foliage is superb in cut greens arrangements.
Rhamnus californica, ‘Coffeeberrry’
R. californica is a very different shrub from r. alaternus, although its cultural requirements are essentially the same. As the name suggests, this species is native to California. R. californica ranges in size from about 4’ x 4’ to 8’ x 8’, depending on the variety, although there is huge variation in the literature about the heights and widths the different varieties eventually attain. Sunset lists the height range as being from 3-15' tall! The leaves are larger, a bit less glossy, and the shape is rounder, with the shrubs generally wider than they are tall. Their architecture is perhaps a bit more interesting than r. alaternus, and the berries on some of the varieties are large and extremely decorative. The species gets larger than most of the named varieties.
R. californica ‘Mound San Bruno’
I begin with this variety because it is my favorite rhamnus, possibly my favorite all around ‘utility’ shrub. It grows to about 6' x 6', although some sources claim it can get twice that wide. The good news is that it doesn’t matter too much, as it is extremely amenable to pruning for shape and size. I use it in drifts as a backdrop for other plants, as a border along my driveway under large oak trees, mixed in with other shrubs and as a stand alone where I need punctuation of good, rich green color. This shrub never looks bad – its deep rich green in the driest months keeps the garden looking lush when many of the other plants falter.
R. californica ‘Eve Case’
Another favorite of many, ‘Eve Case’ is notable mostly for its large, showy berries that start out green and then age to red and finally black. The leaves are a bit larger, darker and coarser than ‘Mound San Bruno’, but equally attractive. Although many sources don’t mention it, ‘Eve’ can get very large, topping 8' and equally as wide once established. It is not quite as amenable to shaping as ‘Mound San Bruno’. I recommend using ‘Eve Case’ only in spots where you will be able to accommodate her mature size. Because her berries are such a standout, she makes a good specimen planting.
R. californica ‘leatherleaf’
Another variety with distinctive berries, ‘Leatherleaf’ is smaller than ‘Eve Case’ and so a better choice for smaller gardens. It tops out around 5-6' and has berries very similar to ‘Eve Case’.
There are several other varieties available to home gardeners, such as R. ‘Mountain Home Ranch’, which is more upright in habit, R. ‘Seaview Improved’, which is a groundcover (the lowest variety grown in the trade) and R. ‘Salt Point’ which is a short, broad shrub. I don’t have personal experience with them, but given my success with the others, they are on my short list of shrubs to try next!
For a climate-appropriate, easy-care shrub with year-round appeal, you can’t do better than a rhamnus! You can find a good selection of R. californica at the local nurseries that specialize in native plants, such as Cal Flora in Fulton (which is also currently growing R. alaternus 'variegata') and Buckeye in Petaluma. R. alaternus is available at Urban Tree Farm in Fulton and Emerisa Gardens in Santa Rosa. If they don’t have the variegated version you can often ask then to special-order it for you.