Alder Buckthorn Plant Care

Alder Buckthorn (Frangula alnus) belongs to the Rhamnaceae family within the Frangula genus. Alder Buckthorn is also known as Glossy Buckthorn, Buckthorn, European Alder Buckthorn.

Alder Buckthorn displays an upright, branching shrub growth habit, reaching up to 6 ft tall with a spread of approximately 4 ft. Alder Buckthorn produces small clusters of tiny, fragrant white flowers.

Leaf size: approximately 3 inches.

Water a young or newly planted Alder Buckthorn every 7–14 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established trees mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Alder Buckthorn thrives in full sun to partial shade.

Frangula alnus tolerates temperatures of 50–80°F. Alder Buckthorn prefers humidity levels of 40–70%.

Well-draining loamy soil with added organic matter for moisture retention. Good drainage is essential for Alder Buckthorn to prevent waterlogging, which leads to root rot and fungal issues.

Feed Alder Buckthorn every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established trees in good soil often need little extra feeding, so let weak growth or pale foliage guide you.

Stop feeding by late summer so new growth can harden before winter.

The PlantoScan app can remind you when to water and when to fertilize each plant.

Choose a spot with full sun to partial shade and well-draining loamy soil with added organic matter for moisture retention. Avoid low spots where water collects after rain.

Alder Buckthorn is suited to USDA Zone 12a.

Plant container-grown or balled-and-burlapped trees in spring or early autumn, setting the root flare at soil level, and water well after planting.

Alder Buckthorn can spread to about 4 ft (1.2 m) and reach about 6 ft (2 m) tall. Space plants about 4 ft (1.2 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.

Planning a row or hedge? Try the tree spacing calculator.

Prune Alder Buckthorn while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.

If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the tree in one year.

Alder Buckthorn is frost-tender (hardy to USDA zone 12). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

Alder Buckthorn can be propagated through seeds, hardwood cuttings. Similar propagation techniques also apply to cascara plant care, which shares the same genus.

See all plants toxic to cats and plants toxic to dogs.

Alder Buckthorn is susceptible to aphids, spider mites, scale insects. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.

Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.

Alder Buckthorn grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. In cooler regions, grow Alder Buckthorn as a houseplant or bring it indoors before the first frost.