Rock buckthorn: complete guide

Rock buckthorn (Rhamnus saxatilis), also called Avignon Berry in some regions, is a compact low shrub from central and southern Europe. The plant is native to mountain areas of the Alps and Pyrenees, growing on rock faces and dry slopes at elevations of 400 to 2000 meters. Rock buckthorn typically reaches 0.5 to 1.5 meters tall and forms a dense bushy framework with small linear to elliptical leaves measuring 10-20 millimeters long. Leaves are green with a slightly rough texture. From May through June the plant produces small inconspicuous yellow-green flowers in clusters followed by fruits that are initially red then turn black at ripeness.

The plant is extremely hardy to USDA zone 4 meaning it survives temperatures to -30 degrees Celsius. It grows slowly and reaches full maturity in 5-7 years. The root system is deep and firm making the plant highly drought-tolerant once established. Under favorable conditions rock buckthorn can live 20 to 30 years or longer in a garden.

Rock buckthorn prefers well-drained slightly alkaline to neutral soil with pH 7.5 to 8. The plant thrives on nutrient-poor rocky stony soil and is very drought-tolerant. Full sun is ideal with minimum 6 hours direct sunlight daily. The plant tolerates partial shade but will be fuller and denser in complete sun. In rainy regions where soil tends to stay moist very well-drained soil must be provided or the plant placed in elevated terrain.

Watering is minimal once established which typically occurs after 2-3 years. During the first growing season water regularly until the plant is established. Thereafter the plant grows excellently without supplemental water except in very dry summers when once-monthly deep watering may help. In winter virtually no water is needed.

Maintenance of rock buckthorn is minimal. Pruning is not essential but can be done in early spring to shape the framework or remove dead branches. Feeding is unnecessary on nutrient-poor soil; actually excessive fertilizer can lead to rank growth. In rich soils a balanced fertilizer once in spring can be given. Disease is rare and the plant is fungal-resistant in dry conditions.

Rock buckthorn is a valuable plant for alpine gardens dry borders and mountainous landscaping. In northern Europe it grows wild in cooler upland regions and provides ornamental value. The plant attracts birds that eat the fruits and scatter seeds so it can produce self-seedlings in favorable locations. Good plant companions include Saxifraga Sempervivum Festuca and Lavandula species. Once established this is a virtually maintenance-free shrub for decades of garden performance.