Brisbane tree guide

Tibouchina

Pleroma species · also called Lasiandra, Glory bush

Tibouchina is the garden name for a group of South American shrubs and small trees, many now classed as Pleroma, grown for masses of purple or pink blooms from late summer through autumn. Larger kinds such as 'Alstonville' make a 4 to 5 metre feature tree, while dwarf varieties suit pots and small gardens. They take pruning well, but their square stems are brittle in wind.

Exotic
4 to 8 m tall
Flowers February to May

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Tibouchina, from Wikimedia Commons — Photo: Stan Shebs, CC BY-SA 3.0, via Wikimedia Commons

Tibouchina at a glance

Height: 4 to 8 m
Leaves: Evergreen
Flowers: Purple, pink, February to May
Origin: South-east Brazil
Family: Melastomataceae

How to identify a tibouchina

In flower they are hard to miss: from late summer into autumn the canopy fills with violet, purple or pink blooms. The leaves are dark green with a paler underside, and the young stems are square in cross-section, a handy clue when the plant isn't flowering. 'Alstonville', one of the best-known larger forms, is a dense evergreen shrub or small tree of 4 to 5 metres. Dwarf types such as 'Jules' grow to only about 1 metre and have small, velvety leaves. Some tree forms reach about 8 metres.

Growing a tibouchina in Brisbane

Burke's Backyard says tibouchinas grow across most of Australia's warm to cool temperate regions, but not in cool mountain districts, inland areas or the hottest parts of the tropics. The popular 'Alstonville' and 'Jules' were both bred in Alstonville, a town near Lismore in northern New South Wales, not far from Brisbane. They like a sunny spot and light, crumbly soil with plenty of moisture through the growing season. Choose a position sheltered from strong wind, because the brittle stems break easily, particularly on young plants. 'Jules' is the most cold-sensitive of them.

What to watch out for

The square stems are brittle and can snap in strong wind, so shelter young plants and check for broken branches after storms.

Brittle branches. The square stems are brittle and can snap in strong wind, especially on young plants.

Pruning and care

Tibouchinas respond very well to pruning and can be trimmed at almost any time of year. Burke's Backyard suggests a harder prune after flowering in late winter, then tip pruning through spring and summer to keep plants dense and bushy. Cut just above new shoots, because these thicken quickly and carry the next flush of flowers. With the right pruning a tree form can be held at whatever height suits the garden. Water well through the growing season, and stake or shelter young plants in windy spots.

Tibouchina: your questions

Short answers, from the sources below.

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When should you prune a tibouchina?

Burke's Backyard suggests a harder prune after flowering in late winter, followed by light tip pruning in spring and summer to keep a tibouchina dense and bushy. It can also be trimmed at almost any time of year.

How tall does a tibouchina grow?

It depends on the variety. Dwarf types such as 'Jules' stay at about 1 metre, 'Alstonville' usually reaches 4 to 5 metres, and some tree forms grow to around 8 metres.

When do tibouchinas flower?

Most tibouchinas flower from late summer into autumn, with purple or pink blooms, and some varieties also flower in winter.

Why are tibouchinas now called Pleroma?

The Australian Plant Census now places species such as Tibouchina urvilleana and Tibouchina granulosa in the genus Pleroma, so newer references use that name. Older books also call them lasiandras.