In Sydney the onset of lush, purple/violet flowers is always a sign of pleasant cooler autumn weather to come.
Tibouchinas originate from South America and like Jacarandas and Poincianas are popular flowering trees in south East Queensland. They grow over a wide range of climatic regions in South America and do the same in Australia. Selective cultivation in the 1960’s, primarily by the Dunstan family in Alstonville, resulted in superior cultivars and secured its widespread popularity.

The following cultivars have proven to be popular garden plants.

Tibouchina Alstonville
So named as it was developed in Alstonville can be either a large shrub or small tree to 5m depending on how it is pruned.
It is covered in autumn with violet/purple flowers.

Tibouchina Kathleen
Large shrub or small tree to 5m. Developed in Alstonville and has rosy pink flowers in autumn.

Tibouchina Noelene
Large shrub or small tree to 5m. Flowers open white and darken to pink resulting in a pretty two toned effect on the shrub.

Tibouchina Jules
Blooms prolifically in autumn with purple/ violet flowers. Tibouchina Jules is a much smaller cultivar growing in a bun shape to less than a metre. This cultivar in particular needs a warm sheltered spot.

Tibouchina Jazzie
Growing to 1.5m this cultivar has violet purple flowers mainly in autumn but also spot flowers rather well at other times throughout the year.


Cultivation

Tibouchinas are fairly hardy once established and tolerate a wide range of conditions but thrive in a well drained, friable, slightly acid soil with reliable moisture. Sandy or heavy clay soils can be prepared with plenty of organic matter. Always mulch Tibouchinas well and fertilise annually in spring.
While Tibouchinas can handle a little dryness once established some extra watering will ensure better growth and more foliage, this is particularly important in summer before flowering.
Tibouchinas do not like hard frosts so choose a warm sunny spot preferably with shelter from strong winds.
Tibouchinas respond well to pruning and the larger varieties can be kept lower with an annual trim, it is essential to prune as soon after flowering as possible. To create a ‘tree’ shape ensure a central leader always has dominance and take out lower branches, the earlier you start this process the better.
The good news is Tibouchinas are practically pest and disease free.

Garden Use

The larger cultivars can be used as trees or free flowering shrubs depending on how they are pruned.
The smaller varieties are great in pots, borders, as shrubby groundcovers or low hedges.
The dark purple colour of Tibouchina blossoms are a standout feature and there are many ways to use such a strong purple, it looks great with white and other shades of the purple/pink/lilac spectrum. I have seen spectacular results when purple Tibouchinas are planted near lilac Crepe Myrtles, the two prolifically flowering plants providing a large area of colour and tag teaming over a long period. You can also zing up that purple with bright orange or purplish reds.

Some plants flowering at the same time you may consider using are:

Strelitzia (Bird of Paradise) – orange
Plumbago – white
Crucifix Orchid – orange
Frangipani – white
Crepe Myrtle – lilac, pinks, white but especially the lilacs
Bougainvillea – purple, pinks, white
Iresine – purple/red
Gardenias – white
Hibiscus – white, pink, purple, red, orange
Vireya Rhododendron - orange