Foothills palo verde

Sun

Full sun; best in an open, hot position.

Water

Very low once established; water deeply but infrequently, allowing the root zone to dry between soakings.

Soil

Well-drained sandy, gravelly or rocky soil, including alkaline soils; avoid waterlogged ground and regularly irrigated lawns.

Height

15-25 ft (4.6-7.6 m)

Spread

15-25 ft (4.6-7.6 m)

Flowers

Spring, sometimes extending into early summer; pale yellow flowers with a cream or whitish upper petal.

Foliage

Tiny paired leaflets appear after rain and fall during drought or cold; the yellow-green bark continues photosynthesis when the tree is leafless.

Growth

Slow

Care needed

Low

• Pollinators
• Drought tolerant
• Heat tolerant
• Wildlife
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Hard

Toughness

Needs looking after

Pick your zone, country, light and whether you have pets.

1. Planting day

   7 ft (2 m)

2. After 1 year

   7 ft (2.1 m)

3. After 2 years

   7 ft (2.3 m)

4. After 3 years

   8 ft (2.4 m)

5. After 5 years

   9 ft (2.6 m)

About 32 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Native to

the US

Growth rate

Slow

• Plant with the root flare at ground level in freely draining soil; do not enrich the planting hole heavily.
• Water deeply through the first two summers, letting the soil dry between waterings and gradually increasing the interval.
• Once established, give occasional deep water only during prolonged hot drought; avoid frequent shallow irrigation.
• Do not routinely fertilize; rich soil and excess feeding are unnecessary.
• Keep mulch away from the trunk and place the thorny canopy clear of paths and play areas.

Pruning. Prune lightly in late spring or early summer, after flowering, to remove dead, damaged or crossing branches and gradually establish clearance. Retain the natural branching structure, avoid topping or heavy thinning, and do not suddenly expose shaded bark to intense sun.

Late winter

Check for frost damage, but wait until new growth shows which branches are dead before cutting.

Spring

Plant once damaging frosts have passed, keeping the root flare above any surrounding mulch.

Late spring

After flowering, remove dead or crossing branches with minimal pruning.

Summer

Deep-water young trees as the root zone dries; check soil moisture before watering established trees.

Autumn

Reduce supplemental watering as temperatures fall and check that runoff drains away from the trunk.

Winter

Keep irrigation off unless conditions are unusually dry; protect newly planted trees during brief hard freezes.

• Use as a small specimen tree in a sunny gravel garden, where its green trunk remains visible when leafless.
• Provide light, filtered shade over a desert planting of agaves, yuccas and low shrubs.
• Plant in a broad, dry courtyard with enough room to keep thorny branches away from seating and circulation.
• Combine with other Sonoran Desert plants in an informal wildlife garden with little supplemental irrigation.

Garden styles it suits: Desert modern, Southwestern, Desert / xeriscape, Dry gravel garden, Wildlife garden and Architectural minimal.

Plant it with: Brittlebush, Desert marigold, Fairy duster, Red yucca, Desert spoon and Saguaro.

Wildlife: Flowers attract native bees and other pollinating insects. Birds use the branches for shelter and nesting, and seeds are eaten by desert wildlife; young trees can also shelter establishing desert plants.

• Root and crown rot in wet soil: improve drainage, keep water away from the trunk and stop frequent irrigation.
• Palo verde root borer: larvae can damage roots, especially on stressed trees; maintain sound watering practices and have declining or unstable trees assessed by an arborist.
• Desert mistletoe: remove affected small branches well below the attachment when practical; seek arborist advice for heavy infestations.
• Frost injury or sunburn after heavy pruning: choose a warm site, protect young trees during freezes and preserve enough canopy to shade previously sheltered bark.

Not known to be toxic to people, cats, dogs or horses. Species-specific safety information is limited, so discourage pets and livestock from eating it; the sharp thorns are the main household hazard and can cause puncture wounds.

• Blue palo verde (Parkinsonia florida)

  Usually larger and faster-growing, with blue-green rather than yellow-green bark, larger leaflets and flowers whose petals are all yellow.

• Mexican palo verde (Parkinsonia aculeata)

  Has conspicuously long, narrow, drooping leaf axes carrying many tiny leaflets, rather than the short leaves of foothills palo verde; it is invasive in parts of Australia and other warm regions.

Palo verde is Spanish for 'green stick', referring to the green bark, while microphylla means 'small-leaved' and Parkinsonia honours the English botanist John Parkinson.

Propagation. Grow from seed. Carefully nick the hard seed coat away from the embryo, soak overnight, then sow in a freely draining mix in warm conditions; move seedlings to their permanent position while young to limit root disturbance.

Accepted botanical name

Parkinsonia microphylla

In the US and Canada

Native in the lower 48 states.

Native range

Arizona, California and Mexico Northwest.

Measured

Average height 700 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.