Native & adapted

Hong Kong orchid tree

Bauhinia × blakeana

Also known as Hong Kong orchid · Bauhinia blakeana · Orchid tree

A fast, nearly evergreen tree with large magenta flowers from late fall into spring. It is sterile, so it skips the messy seed pods of other orchid trees.

FloweringPollinatorHummingbirdFast growingFrost tender

Landscape layersLower canopy

Mature size

20–25 ft tall and 20–25 ft wide

Climate fit

Urban core · USDA 9b–10a · Valley suburbs · USDA 9a–9b

Plant spacing

15–20 ft from other trees; 10 ft from buildings

Frost

Leaves damaged near 28°F; young trees can freeze back below about 25°F.

Special categories

POLLINATOR ATTRACTING

Hardiness guidance

USDA 9b–11; leaves and young branches damaged below about 28°F

Winter chill

None

Typical harvest

Not a food plant.

Before you plant

These conditions determine whether it will thrive.

Soil chemistry

Fast-draining soil. In alkaline Phoenix soil it often needs chelated iron and some soil sulfur to keep leaves green.

Required microclimate

Placement is part of the growing system.

Warm, frost-protected spot, such as a south-facing courtyard or near a wall.

Cold hardiness

Cover in a hard freeze below 28°F

Leaves, flowers and small twigs burn around 28 to 30°F, though the bigger limbs take a couple degrees more and trees regrow from the wood. Cover young trees on frost nights, and throw cloth over established ones when a hard freeze is forecast, since it blooms right through the frost season.

Leaves and wood: damaged below 28°F

Heat tolerance

Shade from late-afternoon sun

Handles Phoenix heat well when it sits in a green, watered landscape, but scorching 110°F afternoons in bare gravel stress it. Keep it off hot west exposures, because the trunk and branches sunscald, and never thin the canopy hard.

Sources:

asu.edu , phoenixtropicals.com

Right plant, right place

Will Hong Kong orchid tree grow at your Arizona property?

Branches can be brittle in monsoon winds. Train a strong central structure while young and keep it out of the most wind-exposed corners.

Best regional fit: Urban core · USDA 9b–10a, Valley suburbs · USDA 9a–9b.

Light

Sun exposure

Full sun to light afternoon shade. Young trees appreciate afternoon shade their first summer.

Water

Irrigation

Moderate. Deep water every 7 to 10 days in summer.

Fruit set

Pollination

Sterile hybrid; it does not set seed. Hummingbirds and bees visit the flowers.

Harvest

How to use it

Grown for flowers and shade.

Planting & stewardship

How to help Hong Kong orchid tree thrive

1
Stake lightly the first year and prune for a strong single or low multi-trunk form.
2
Feed with an iron-rich fertilizer in spring if leaves yellow.
3
Cover young trees on frost nights.
4
Thin crowded branches after flowering to reduce wind damage.

Read the horticultural reference ↗