Tree Wisteria

Tree Wisteria (Bolusanthus speciosus) gives you the hanging violet flowers of a wisteria vine on a self supporting tree of about 6m by 3m. The crown is slender and lightly weeping, the roots are well behaved, and it is deciduous, so winter sun still reaches whatever grows beneath it. Purple pea flowers open in spring and the bees find them within days.

Why you'll love it

• Wisteria flowers without the vine. Purple sprays hang from the branches each spring, without the pergola, wire and annual wrestling a climbing wisteria demands.
• Narrow enough for a small block. At roughly 6m by 3m it fits between a house and a boundary where a spreading shade tree would crowd everything out.
• Roots that stay out of trouble. The root system is non-invasive, one of the safer choices near paving, a driveway or a service trench.
• Genuinely tough once established. Drought, heat and wind tolerant, so a hot western aspect or an exposed corner does not faze it.

Where it works best

Feature planting. One tree in a lawn or courtyard carries the whole spring display. The weeping habit reads best where you can walk right around it.

Driveways and avenues. Space trees 4m to 5m apart. The narrow crown means you are not cutting branches back off the car every second year.

Small gardens and large pots. A pot 600mm or wider holds it for years at a reduced height, provided you water through summer.

Growing Tree Wisteria in Australia

Position and climate. Full sun. It suits tropical, subtropical, warm temperate, Mediterranean and arid or semi-arid gardens. It takes light frost only, so cold tablelands and hard frosting southern districts sit outside its range, and young trees want protection through their first two winters even in mild areas.

Soil. Drainage is the one real requirement, and sandy or gravelly ground suits it. On clay, plant proud on a raised mound with compost and coarse grit through the bed, then mulch 75mm deep and keep it off the trunk.

Water and feed. Deep soak weekly through the first two summers, then only in long dry spells. A complete slow release fertiliser in early spring is plenty, because heavy nitrogen buys leaf at the expense of flower.

Pruning. Very little is needed. Take out crossing branches and lift the lower limbs in late winter, while the tree is bare and the structure is easy to read.

What to expect when it arrives

It is grown in two sizes. The 300mm plant is a young single leader tree that needs staking for its first year. The 45 litre is semi advanced, with a formed trunk and a head of branches already there. Being deciduous, a winter delivery may arrive bare, which is normal and not a fault.

Plants are delivered Australia wide, with delivery from $29.95, and advanced and large stock is freighted at cost. Expect the first real flowering in the second or third spring after planting. Every tree carries our 30 day healthy plant guarantee.

Plant care guides and related reading

• Compare the flowering trees collection.
• More options for a tight block: small trees for urban gardens.
• Planting near paving: trees with non-invasive roots.
• Our guide to the best trees for lining a driveway.

Common questions

Is it related to climbing wisteria?

No. It is a southern African legume in a different genus, and the name comes from the flowers, which hang in similar violet sprays. It does not twine, sucker or need a support structure.

How fast does it grow?

Moderate, roughly 30 to 50cm a year in a warm garden watered through its first few summers. Growth is slower in dry inland gardens and in cooler southern areas.

Will it handle frost?

Light frost only. An established tree shrugs off a light touch, but young trees need cover, and districts with hard winter frosts should choose something hardier.

Can I grow it in a pot?

Yes, in a pot 600mm or wider with a free draining mix. Expect around 3m rather than 6m, and water consistently through summer, since a potted tree cannot chase moisture.