Tibouchina semidecandra Glory Bush
This attractive shrub is, alas, still little seen in cultivation. Perhaps now that wider use is being made of window glasshouses and glass plant-cases – in other words of equipment ensuring both sufficient light and, more important, the high humidity required by many members of the Melastomataceae family — the situation will improve. Genera such as Osbeckia, Heterocentron, Bertolonia, Sonerila, Miconia and many more would definitely deserve it, for their numbers include both foliage plants and ones with interesting and often large.
Anyone who has been to one of the larger parks in Central or South America has surely admired the large tibouchina shrubs with their huge gentian blue flowers up to 12 cm (43/ 4 in) across. Tibouchina semidecandra, native to southern Brazil, where it grows at higher elevations, has become widespread in cultivation wherever conditions are congenial – chiefly in subtropical regions.
In cultivation it generally does not exceed 1 m (3 ft) in height, whereas in the wild, according to reference books, one will come across specimens up to six times as tall. Because the shrub has unruly growth it should be hard pruned in spring to keep it shapely and compact and thus it is unnecessary to worry about it getting too big.
In summer, these plants tolerate conditions indoors as well as being moved out to the garden or balcony. In winter, it is recommended to keep the temperature between 8 and 10°C (47 and 50°F) but they can also be grown in a warmer room without damage. However, in this case they require frequent and ample ventilation. The compost must be light, acid and lime-free, best being a mixture of peat, leaf mould and sand with bits of charcoal added. One of the peat-based soilless composts would also be ideal.
Propagation is not difficult. Slightly woody cuttings inserted in a peat and sand compost in a warm propagator (22 to 25°C [72 to 77°F]) in spring will root fairly readily.
There are many other species besides this one that are worthy of note for the genus Tibouchina embraces 250 all told.