Alstonville Tibouchina

Alstonville Tibouchina (Tibouchina lepidota 'Alstonville') is bought for the few weeks each autumn when the whole canopy turns solid purple and the leaves disappear behind the flowers. It makes a rounded evergreen tree of about 4m tall and 3m wide, fast enough to be doing real work in the garden within three years.

Why you'll love it

• Autumn colour you can plan around. Flowering peaks through March and April, and on an established tree the purple covers the canopy rather than dotting it.
• Fast without being coarse. It gains height quickly while holding a neat rounded head.
• A screen that flowers. Planted 2m apart it forms a soft evergreen barrier that pays you back once a year.
• Coastal ready. Salt tolerant and comfortable in humidity, which suits exposed beachside and subtropical gardens.
• Scaled for small gardens. At 4m it fits a courtyard where a larger flowering tree would not.

Where it works best

Feature planting. One tree in lawn or against a light coloured wall, because the purple reads best with space around it.

Flowering screen. Plant 2m apart in a single row. The canopies meet without crowding, and light still reaches the sides so the screen flowers along its length.

Mass planting. Groups of three or five at 2m spacing give a block of colour a single tree cannot.

Growing Alstonville Tibouchina in Australia

Position and climate. Full sun for the heaviest flowering; part shade gives fewer flowers and looser growth. It suits tropical, subtropical and warm temperate gardens, which covers Brisbane, northern New South Wales, coastal Sydney and Perth. It is frost tender, so colder southern and inland gardens want a warm sheltered wall or a pot that can be moved. Shelter it from strong wind, which strips the flowers.

Soil. Slightly acidic, free draining and enriched with compost. It resents lime and waterlogged clay, so on heavy soil plant on a raised mound and mulch 75mm deep, clear of the trunk.

Water and feed. Deep soak twice a week through the first summer, then weekly in dry spells. Feed in early spring and again after flowering, avoiding heavy nitrogen late in summer.

Pruning. Prune as soon as flowering finishes, cutting back by up to a third. It flowers on new wood, so a late prune removes next season's display. Annual trimming keeps the canopy dense rather than twiggy.

What to expect when it arrives

It is grown in three sizes. Tubestock is the economical start for a screen or mass planting, and it catches up quickly because this plant grows fast. The 200mm pack of six suits several trees at once, and the 45L is an advanced plant with a formed head and height already made.

Plants travel upright and are delivered Australia wide, with delivery from $29.95 and a minimum order of $300 before delivery. Advanced and large stock is freighted at cost. Expect a month of settling, then a first worthwhile flowering in the second or third autumn. Every plant is covered by our 30 day healthy plant guarantee.

Plant care guides and related reading

• Alstonville tibouchina care and getting the autumn purple
• Browse more flowering trees
• Compare privacy and screening plants
• Preparing soil before you plant

Common questions

Why is mine not flowering?

Too much shade, or pruning at the wrong time. It flowers on wood produced after the previous display, so a cut in late winter or spring takes the buds with it.

How hard can I prune it?

Up to a third of the canopy immediately after flowering, every year if you want it dense. Neglected plants can be cut harder and will reshoot, though they skip a season of flowers.

Will it grow in Melbourne or Adelaide?

In frost free coastal suburbs, yes, given a warm north facing spot with wind protection. Where frosts are regular it is safer in a pot that can be moved to shelter.