Accent · Sonoran native
Soaptree Yucca
Yucca elata · Asparagaceae (Agavoideae)
Also called: Soapweed, Palmella, Soapweed Yucca
Soaptree Yucca (Yucca elata) is a very low-water accent native to the Sonoran Desert region well suited to Tucson and the low desert.
Soaptree Yucca at a glance
- Water use
- Very Low (established)
- Sun
- Full sun with reflected heat; not for shade.
- Mature size
- Typically 6-15 ft H (old plants to ~20 ft) x 6-10 ft W; flower stalk adds 3-6 ft above the foliage.
- Growth rate
- Slow (roughly an inch or so of trunk per year); develops a branching trunk with age. AMWUA rates it 'moderate' under landscape irrigation.
- Bloom
- Creamy white, bell-shaped flowers in a large cloud on the upper half of a tall stalk., Late spring to early summer, usually May-June.
- Cold hardiness
- Very cold hardy, to about 0°F or below (reported to -20°F in dry soils); USDA zones 6-11.
- Soil
- Well-drained sandy, gravelly, or rocky desert soil; tolerates caliche and alkaline soils. Avoid soggy, poorly drained sites.
- Native range
- Native to the Sonoran and Chihuahuan deserts and desert grasslands of Arizona, New Mexico, west Texas, and northern Mexico; a true Arizona native.
- Best used as
- Signature desert specimen/accent, Sculptural silhouette and vertical interest, Native and habitat plantings, Xeriscape and water-harvesting landscapes, Erosion control on slopes
- Wildlife
- Obligate mutualism with yucca moths (Tegeticula) that pollinate it; flowers and stalks browsed by deer, rabbits, and javelina; provides cover and nesting; larval host value. Roots and leaves historically used for soap (saponins) and fiber.
- Toxicity
- Low toxicity; contains saponins in roots/leaves that can cause mild GI upset if eaten, and leaf tips are sharply pointed. Flowers and fruit are edible to wildlife and were eaten by Indigenous peoples.
How to grow Soaptree Yucca in Tucson & the low desert
Watering
Extremely drought tolerant once established; established plants need water only every 3-4 weeks in the hottest months and little to none the rest of the year. Deep, infrequent soaks that fully drain are best; overwatering causes rot and overly soft growth.
Fertilizer & nutrients
Not needed in native desert soil. If desired on young transplants, a single light spring feeding of slow-release fertilizer can encourage establishment, but mature plants require no fertilization.
Pruning & care
Minimal. Remove spent bloom stalks and groom dead lower (skirt) leaves for a clean trunk if desired, or leave the 'grass skirt' natural. Never top or cut the growing crowns.
Notes
Arizona's signature roadside yucca, with very narrow, flexible, grass-like blue-green leaves edged in white curling fibers, forming a fine-textured spherical head atop a slender trunk. Slow to establish trunk; buy at desired size. Iconic vertical desert accent.
Sources: AMWUA – Landscape Plants for the Arizona Desert (Soaptree Yucca profile); Arizona-Sonora Desert Museum plant care sheets (Yucca elata); University of Arizona Cooperative Extension; Tucson.com/UA 'Plant of the Month: Soaptree Yucca'