Harpephyllum caffrum aka Wild Plum

Wild Plum is relatively easy to grow once established, with the main consideration being frost sensitivity. It tolerates a wide range of soil types including poor soils, requires moderate care, and grows quickly (1-1.5 meters per year). The tree thrives best in frost-free subtropical climates and needs minimal maintenance once settled. In colder regions (below USDA zone 9), it can be grown in containers and brought indoors during winter.

Water Harpephyllum caffrum regularly during the growing season, especially during hot weather. Once established, the tree has moderate water requirements and tolerates some drought. Young trees need consistent moisture to establish their root system. In subtropical climates, natural rainfall is often sufficient for mature specimens, but supplemental watering benefits fruit production during dry spells.

Harpephyllum caffrum is remarkably adaptable and tolerates a wide range of soils including sandy, loamy, and even poor soils. Good drainage is beneficial, and the tree prefers neutral pH. For container growing, use a well-draining potting mix. Despite its tolerance for various soil conditions, the tree performs best in reasonably fertile soil with adequate organic matter.

Harpephyllum caffrum thrives in full sun exposure with at least 6 hours of direct sunlight daily. It can tolerate semi-shade (3-6 hours of direct sun) but performs best in bright, direct sunlight. Full sun promotes better flowering, fruiting, and the characteristic dense crown development. In hot climates, some afternoon shade may be beneficial for young trees.

Harpephyllum caffrum propagates easily from seeds, which germinate in just 7-11 days with a high success rate. Seed propagation is generally more reliable and faster due to the species' naturally high germination rate.

In gardens and landscapes, Harpephyllum caffrum typically reaches 10-15 meters tall with a spread of 8-10 meters, forming a dense, rounded crown. In its native forest habitat, exceptional specimens can grow up to 35 meters with trunk diameters reaching 60cm. The tree grows rapidly at 1-1.5 meters per year when young. Its candelabra-like branch structure creates excellent shade, making it popular as a street and park tree.

Harpephyllum caffrum is native to southern and eastern Africa, occurring naturally from the Eastern Cape northward through KwaZulu-Natal, Eswatini (Swaziland), southern Mozambique, Limpopo, and into Zimbabwe. The specific epithet 'caffrum' refers to Kaffraria, the historical name for part of what is now Eastern Cape, South Africa. The tree thrives in the summer rainfall regions of eastern southern Africa rather than the winter rainfall areas of the Western Cape.

Harpephyllum caffrum is frost-sensitive and grows best in subtropical to tropical climates. It tolerates minimum temperatures down to about 30°F (-1°C), making it suitable for USDA zones 9-11. In colder regions, grow it in containers and bring indoors when frost threatens, avoiding drafty locations. Plant outdoors in spring or early summer to allow establishment before cooler weather. The tree prefers warm, moderate temperatures and thrives in its native summer rainfall climate.

Harpephyllum caffrum grows best outdoors in frost-free subtropical and tropical climates (USDA zones 9-11). In suitable climates, it makes an excellent shade tree, street tree, or garden specimen requiring minimal care once established. In cooler regions, it can be grown in large containers on patios during summer and overwintered indoors.

Harpephyllum caffrum produces small, inconspicuous whitish-green flowers throughout summer (October to February in the Southern Hemisphere). The species is dioecious, meaning male and female flowers grow on separate trees—you need at least one tree of each sex for fruit production. Plant at least three seedlings to ensure having both sexes. Flowers attract bees and other pollinators.

As a dioecious species, Harpephyllum caffrum relies on insects (primarily bees) to transfer pollen from male to female trees. Both sexes are required for fruit production—only female trees bear fruit. Plant at least three seedlings to increase the likelihood of having both male and female trees, as the sex cannot be determined until flowering age. The small greenish-white flowers attract bees and other pollinating insects.

The fruits of Harpephyllum caffrum are edible with a distinctive sour, slightly acidic taste. The oval red fruits (about 25mm across) ripen from December to March and are commonly used to make jams, jellies, and preserves. The sour flavor also makes them excellent for producing rosé wine. While edible raw, most people prefer the fruit processed due to its tartness. The fruit contains a single seed surrounded by juicy red pulp.

The bark of Harpephyllum caffrum has significant traditional medicinal uses in southern Africa. It is primarily used to treat skin conditions including acne and eczema, applied as facial saunas and skin washes. Powdered burnt bark treats sprains and bone fractures. Root decoctions are traditionally used for paralysis. Scientific studies have validated many of these uses, confirming antibacterial, antifungal, anti-inflammatory, and antioxidant properties in bark extracts.

Beyond its edible and medicinal properties, Harpephyllum caffrum provides several practical uses. The bark produces a mauve or pink dye for coloring fabrics. The pale reddish wood is hard, strong, and elastic, making it valuable for furniture, construction beams, and carved curios. As a landscape plant, it serves excellently as a shade tree, street tree, or ornamental specimen, prized for its dense rounded crown and attractive new growth flushes.

Harpephyllum caffrum is generally a robust tree with few serious pest or disease problems. The leaves serve as food for larvae of the common hairtail butterfly (Anthene definita) and Eggar moth (Lasiocampa kollikerii), though this rarely causes significant damage and supports local biodiversity. The tree belongs to the Anacardiaceae family (related to mango and cashew), so watch for similar pests that affect these relatives. No major diseases are commonly reported.

In subtropical climates, Harpephyllum caffrum needs increased watering during the hot growing season (summer) and reduced watering in cooler months. Flowering occurs in summer with fruit ripening in autumn. In marginal climates, protect from any frost in winter. Container-grown trees should be moved indoors before temperatures drop below 30°F (-1°C).