Othonna is a genus of more than 100 African plants in the Sunflower family (Asteraceae). These are evergreen or deciduous geophytes, dwarf succulents or shrubs concentrated in the Western Cape Province of South Africa and also in southern Namibia. A few species occur in summer rainfall parts of southern Africa. The genus is closely allied to Senecio and can be distinguished principally by details of the involucre.
The form or habit of Othonnas is very diverse. Leaf diversity is also notable in this genus. A few species possess highly succulent leaves (Othonna capensis, Othonna sedifolia) but most have bifacial leaves that are only slightly succulent. Size and shape are variable, with most species having from 0.4 to 4 inches (1 to 10 cm) long leaves.
The bright yellow (occasionally white or purple) flowers are the most distinguishing characteristic of the genus and the flowering times differ from different species. Some bloom just before the beginning of their summer rest and others bloom after fall growth beginning.
Growing Conditions and General Care
Othonna plants have a variable range of habitats, some grow in a very hot, arid regions, but they avoid the intense desiccating rays of the north and west sun, growing between rocks in southern slopes. A few species by contrary grow in strong direct sunlight in arid situations that become very hot and dry as well as saturated for a few weeks during their growing period. All Othonnas grow in very open situations with plenty of free air circulation all around.
Othonnas fleshy leaves and daisy-like flowers make them excellent in a desert or rock garden (where hardy), or indoors as houseplants or greenhouse specimens.
Othonnas tend to be fairly hardy but some of them as Othonna cacalioides can be extremely difficult in cultivation. If you do not give them the right conditions, space to develop the radicular system, better to keep them in flat pots. In summer protect plants from direct sunlight. In growing season they like to be moist, fresh and plenty of light. They do not like temperatures below 50 °F (10 °C).
In the warmer months, Othonnas go into their dormancy period. Stop watering, place them in a shaded, cooler area, away from getting direct sunlight, relatively dry and with good air circulation. In the fall, when nights cool down, the plants may start growing on their own, but a good soaking will help them to leaf out.
A typical succulent soil mix should be suitable for growing Othonnas but additional drainage material would be recommended.
Start seed in spring at 64 to 70 °F (18 to 21 °C). Plants can also be propagated from basal or semi-ripe cuttings in late summer using bottom heat.