Olneya tesota

Common Names

Desert Ironwood, Ironwood, Palo De Hierro, Palo Fierro, Tesota

Summary

Desert Ironwood, native to the Sonoran Desert, is a slow-growing tree or large shrub that reaches about 15–30 ft tall and wide, with gray fissured bark, spines on twigs, and small gray-green pinnate leaves with 6–20 leaflets; lavender to pinkish-purple pea-like flowers appear in spring, followed by woody pods and dense wood that sinks in water, making it a keystone species that fixes nitrogen and provides shade, habitat, and a nurse plant for other desert species.

Cultivation favors full sun and well-drained soils, with drought tolerance once established and minimal irrigation; nitrogen fertilization is not needed, and pruning is light to maintain shape; transplanting can be difficult due to a deep taproot; propagation is by seed (scarification may improve germination). It suits xeriscapes and desert landscapes for shade and visual interest, and its dense wood is used for fuel and carvings, while wildlife benefit from its shade, nectar for pollinators, and seed resources.

Lifecycle

Perennial

Height

15-30 feet

Spread

20-50 feet

Hardiness Zones

Zones 9-11

Sunlight Requirements

Ideally full sun, tolerates partial shade.

Soil Type

Well-drained sandy or rocky soils; pH 6.0–8.5.

Soil Drainage

Well-drained soil

Soil pH

5.5–8.5

Bloom Color

Lavender to pinkish-purple

Bloom Time

Spring

Foliage Color

Gray-green

Fall Foliage Color

No fall foliage color; evergreen

Leaf Lifecycle

Semi-deciduous

Growth Rate

Slow-growing; 5–10 years to reach about 10–15 ft.

Seasons of Interest

Spring, Summer, Fall, Winter

Propagation Methods

Seeds, Cuttings, Air layering, Grafting, Cloning

Attracts Wildlife

Bees, hummingbirds, butterflies, other pollinators, and birds are attracted.