Another beautiful shrub for a greenhouse heated to a temperature of at least 10°C. (50°F.) in winter, is Tibouchina semi-decandra. This evergreen has rich purple blooms, with a velvety appearance, which it bears over a long period in summer. Like the streptosolen, T. semi-decandra can be grown in pots or tubs or in a border. In this country it is known as the Brazilian Spider Flower, but in some other countries I believe it has the amusing name Yesterday, Today and Tomorrow, an allusion to the fact that as yesterday’sare beginning to fade today’s flowers are a rich bluish purple and tomorrow’s are just beginning to open in an even richer shade of purple.
This plant grows well in John Innes No. 3 Potting Compost and any repotting should be done in February or March. Water the plant freely during summer, but reduce the amount in winter as there must be a definite resting period. Established plants need feeding regularly with liquid or soluble fertiliser in spring, summer and autumn to keep them flowering and in a healthy condition.
The growths can be trained to wires or canes against the side of the house, but I prefer to see it restricted in size to form a bush. Suchas is necessary to keep the plants reasonably compact should be done after flowering.
Cuttings made from half-ripe shoots can be rooted in a propagating frame with a temperature of 21 to 27°C. (70 to 80°F.) at any time between early spring and autumn.