Tibouchinas (Tibouchina sp.) should be pruned after flowering or whenever necessary to promote dense, bushy growth. The plant shown in our segment was looking spindly and ugly, so Don pruned it back severely. He started by removing all the dead and dying wood. He then shortened all the branches by about two thirds, even some that were up to 70mm or 3″ thick.
Many people would be alarmed at Don’s harsh renovation pruning demonstration. However, Don showed another tibouchina that had been treated in exactly the same way and had already grown back into a beautiful, shapely plant. He explained that with this sort of severe pruning you will probably lose one year’s flowering, but in the following and subsequent years the plant will produce more and more flowers.
Tibouchinas, also known by their old name lasiandras, are native to south-east Brazil. They have purple or pink flowers in late summer or autumn, with some varieties flowering in winter. Popular varieties include ‘Alstonville’ (tree to 5m or 15′, with violet/purple flowers), ‘Kathleen’ (tree to 7m or 20′, pink flowers) and ‘Jules’ (dwarf shrub to 1m or 3′, with purple flowers). Tibouchinas will grow in most warm to cool temperate regions of Australia but are not suited to cool mountain districts, or the warmest parts of tropical Australia.
Tibouchinas like a sunny spot and a light friable soil with plenty of moisture during the growing season. Protect from frosts. Their square stems are brittle, so they also need protection from strong winds, especially when young.
General pruning tips:
prune at just about any time of the year
prune so that you think the whole thing either works better or looks better
always take your time and cut carefully and gently
aim for a clean, neat wound
when pruning large branches first make a small cut underneath to stop the bark tearing
when you’re unsure, prune in stages; you can always take more off but it’s hard to stick bits back on again
don’t leave stubs poking out that might injure somebody – safety first
be ruthless when necessary
A good pair of pruning secateurs can cost $70 – $120.