This is a group of evergreen plants which used to be commonly called Lasiandra but is known now as Tibouchina. The 250 to300 species of shrubs and small trees come from South America with the greatest number of species coming from Brazil. According to my references the names are very mixed up and are under review. Some garden forms are misnamed and are probably of hybrid origin.
We have several different species growing here with most flowering over the Autumn to Winter period although some seem to flower in the Summer and others all year. In the wild most flowers are purple, violet or white, but with crossing, pinks and reds are coming into cultivation.
Generally the fruit is a dry capsule but when I was in the Cook Islands there was a fleshy fruited one which was reasonable to eat. In warmer countries some species have become weeds.
Most garden Tibouchina require protection from frost and only a few are tolerant of some wind. If they are growing in a windy spot, keep them pruned back to give a sturdy plant.
Hard pruning to keep them to size is quite alright but I would probably do it over the summer months. I imported a Tibouchina granulosa many years ago from Australia and when it was about three years old gave it a hard prune in the spring when the sap was rising. The sap wouldn’t stop flowing and it bled to death.
Free draining soils are best for good growth and although they can stand dry conditions they do appreciate a good watering.