ONE sign that summer is drawing to a close is the explosion of colour in tibouchinas. Probably the most well-known of this group of tropical flowering trees and shrubs is a variety called Alstonville, developed by the late Ken Dunstan in Alstonville, northern NSW, in the 1960s. Tibouchinas (then known as lassiandras) had been grown in Australia before this, but they were not terribly popular as they were somewhat straggly in habit and required frequent pruning.
Ken Dunstan and his family started experimenting with tibouchina seed imported from Brazil. They grew and selected several superior forms of a few different species, but it was not until Dunstan initiated the planting of Alstonville as a street tree in his home town that tibouchinas became popular.
Alstonville is a fast-growing evergreen tree to about 4-5m tall, bearing masses of satiny deep purple single flowers up to 10cm across, with prominent stamens. The peak flowering period is from late summer into winter, but a few spring flowers are not uncommon. Because Alstonville is such a compact tree, it fits readily into the average suburban garden and, of course, makes a magnificent street tree.
Other varieties produced from the Dunstans' work include Kathleen (named for Ken's sister), which grows to about 6m and produces pink flowers. Noelene was named for Ken's wife, and grows 4-5m tall with flowers that open white and turn pink as they age. Ken's daughter-in-law didn't miss out - he named Jules, a dwarf form to 1m, with flowers similar to Alstonville, for her.
Thanks to the work of the Dunstan family, tibouchinas have become a mainstay of gardens in the warmer parts of Australia, and other new varieties have been produced since then. So now we have Jazzie, which forms a rounded shrub to about 1.5m, and one of my absolute favourites, Peace Baby. This one grows about 60cm x 80cm and has masses of gorgeous large white flowers with delicate pink stamens. I planted some in my garden a couple of years ago. They have been in full bloom since October, and are showing no sign of slowing down yet.
Tibouchinas love water and perform best in full sun to part shade. In a dry spot, they will appreciate protection from the afternoon sun. The compact varieties are well suited to pot culture. Prune lightly after flowering to keep them compact and neat. Sometimes older, neglected trees can become a bit straggly, and these can be re-invigorated with severe pruning.
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