Clerodendrum: Greenhouse Plants
T – tropical, minimum of 18°C (65°F)
The most commonly grown is the very attractive Clerodendrum thomsonae, the Bleeding Heart Vine from tropical West Africa. Petals are bright crimson, protruding from a creamy-white calyx providing a most effective contrast. Although this plant prefers tropical conditions I have found that it will overwinter at lower temperatures in a dormant state. In the autumn plants should be pruned back to within a few buds of older growth. Water sparingly until the spring, when it will produce new shoots that will quickly look for a climbing frame. However, to appreciate the full glory of the plant it should be given its head and allowed to climb as high as it likes in a tropical atmosphere, where, providing it has sufficient light, it will flower spectacularly. The same can be said for C. splendens, the flowers of which are vivid scarlet. If this requires pruning, do so as drastically as you like after flowering and it will grow back in leaps and bounds. There is a hybrid between these two species, C. speciosum, but I do not consider it as a rival to either of its parents. C. X speciosissimum from Java is an attractive shrubby species worth growing if you can find a source of seed. Large terminal panicles of scarlet flowers are produced in the autumn and winter. C. fragrans pleniflorum is another shrubby species from China and Japan which can do well at lower temperatures. It has white double flowers suffused with pink and heavily scented. Both these grow to 1.2 m (4 ft). Seed sown when ripe or in the spring should yield flowering plants by the following season. Cuttings of side shoots 8-10 cm (3-4 in) long should root easily at 21°C (70°F) and it is worth looking around the base of plants for detachable suckers. Have a go at takingalthough I cannot vouch for this myself.