Crotolaria capensisDescription, History & Interesting Facts:

The genus Crotalaria consists of about 600 species of annuals, perennial herbs, and shrubs , occurring in warmer countries world-wide,  with some 500 species from Africa.  The Cape rattle-pod belongs to the pea and bean family and the genus name Crotalaria comes from the Greek word krotalon, meaning castanet, and refers to the rattling sound the ripe seeds make in the dry seed pods. The species name capensis means of the Cape; and the common name Cape laburnum refers to its flowers which resemble those of the European laburnum (Laburnum anagroides), but this can be misleading because it is not related to the Laburnum. 

It can be found in the Western Cape, Eastern Cape, Transkei, KwaZulu-Natal, Free State, Gauteng, Mpumalanga, Limpopo, Swaziland, Mozambique and Zimbabwe;  occurring in fynbos, grasslands, along rivers and streams, on forest margins, and in coastal bush.  Being a member of the legume family of plants Crotalarias have a symbiotic relationship with bacteria that live in their roots and are able to fix atmospheric nitrogen in the roots and making it available to the plant. When the host plant dies, the nitrogen is released into the soil and becomes available to other plants. This, together with their fast growth makes Crotalarias excellent pioneer plants and they are often the first plants to re-colonise a damaged or disturbed area.

The Cape rattle-pod is a fast growing evergreen which can be trained into a little tree or a much branched shrub which is a delight in any garden. If left un-pruned and under optimal conditions it can grow up to 5m tall, but is generally kept at +-2 to 3m tall in the garden. It develops a slender main stem and drooping branches and the new stems are velvety to the touch. The leaves are bright green, and the young growth is silvery blue.

The large sweetly scented pea flowers have bright yellow petals which are often edged with red, and are borne in long pendulous sprays mainly from October to April, but flowers can often be found on the bush throughout the year.  The flowers are pollinated mainly by carpenter bees and will attract sunbirds and butterflies to your garden. The fruits are inflated hollow pods and when the pods are dry, they rattle in the wind. Blue butterfly larvae of the family Lycaenidae parasitize the pods and Chameleons are often found on the bushes waiting to predate the adult butterflies.

In the Garden:

This plant is highly recommended for new gardens and gardeners alike, because it is quick and easy-to-grow. It is so versatile, making a decorative hedge or informal screening plant; and is wonderful in the mixed shrub border. It also makes a good specimen flowering tree, suitable for even the tiniest of gardens.

Cultivation/Propagation:

This wonderful evergreen thrives in full sun and does best in regions with moderate to good rainfall because it is not very drought hardy and does not look at its best if stressed for water. In hot dry summer rainfall regions and in the winter rainfall regions, it will need regular watering. It is very wind tolerant and hardy to moderate frost, tolerating temperatures below zero once established. Protect young plants from frost.

The Cape rattle-pod will grow in most well-drained garden soils and is tolerant of soils ranging from acidic to slightly alkaline; adapting to chalk, clay, clay loam, loam, loamy sand, sandy clay, sandy clay loam and sandy loam soils. It prefers high fertility, so for optimum growth enrich the soil with compost, mulch the roots, and water and feed regularly.

Prune the plant into shape when it is still young; to grow a small tree, prune away the lower branches to form a standard, to encourage a bushy shrub, pinch back the growing tips.

The plant seeds itself freely but unwanted seedlings are easily removed.

Fresh seeds germinate within about 2 weeks if sown in autumn or spring, and seed is often sown in situ, especially when the plants are to be used for rehabilitation projects. Soaking seed in hand-hot water and treating with a fungicide that combats pre-and post-emergence damping off, although not essential for germination, will increase the number of successful seedlings. Prick out the seedlings soon after the first pair of true leaves develop. The growth rate is fast, up to 1m per year; and the plants will flower in their second year. 

Propagation from hardwood cuttings or from young growth may also be successful.