Vachellia karroo (Hayne) Banfi & Galasso
Sweet Thorn, Common Acacia, Karoo Thorn
Acacia karroo (basionym), Acacia capensis, Acacia dekindtiana, Acacia hirtella, Acacia inconflagrabilis, Acacia reticulata, Mimosa reticulata
Bloom Time: Early summer
Vachellia karroo is a shrub or small to a medium-sized tree that grows up to 40 feet (12 m) tall. It has a rounded crown, branching fairly low down on the trunk. It is variable in shape and size. The bark is red on young branches, darkening and becoming rough with age. Sometimes an attractive reddish color can be seen in the deep bark fissures. The leaves are finely textured and dark green. The thorns are paired, grayish to white, and are long and straight. On mature trees, the thorns may be quite short. The flowers appear in early summer in a mass of yellow pompons. The seed pods are narrow, flat, and crescent-shaped. They are green when young becoming brown and dry.
How to Grow and Care
Acacia requires full sunlight and grows in nearly any type of soil, including sand, clay, or soil that is highly alkaline or acidic. Although Acacia prefers well-drained soil, it tolerates muddy soil for short periods. Acacia is basically a plant-it-and-forget-it type of tree, although a young tree may need protection from wildlife while it develops its defense system. During the first year, the tree benefits from an orchid fertilizer every three to four weeks. After that time, you can feed the tree a general-purpose fertilizer once every year, but it isn't an absolute requirement. Acacia requires little or no water.
Acacia may need occasional pruning during the dry months. Avoid pruning leafy, green areas, and trim only dead growth.
Although the tree is disease-resistant, it can sometimes be affected by a fungal disease known as anthracnose. Additionally, watch for pests such as aphids, thrips, mites, and scale. See more at How to Grow and Care for Acacia.