Wildflower/Perennial · Sonoran native
Desert Milkweed
Asclepias subulata · Apocynaceae (formerly Asclepiadaceae)
Also called: Rush Milkweed, Ajamete
Desert Milkweed (Asclepias subulata) is a very low-water wildflower/perennial native to the Sonoran Desert region well suited to Tucson and the low desert. It grows to 3-4 ft H x 2-3 ft W in full sun, with a moderate to fast growth rate.
Desert Milkweed at a glance
- Water use
- Very Low (established)
- Sun
- Full sun; tolerates reflected heat
- Mature size
- 3-4 ft H x 2-3 ft W
- Growth rate
- Moderate to fast
- Bloom
- Pale creamy yellow to greenish-yellow, Spring through fall, peaking in warm months; can bloom nearly year-round with adequate warmth
- Cold hardiness
- Hardy to about 25 F; USDA zones 8-11
- Soil
- Sandy or rocky, well-drained native desert soils; tolerates poor, alkaline soils; demands excellent drainage
- Native range
- Sonoran and Mojave Deserts of Arizona, southeastern California, Nevada, Baja California and Sonora, Mexico
- Best used as
- Pollinator garden, Butterfly/monarch host plant, Accent in desert and xeriscape plantings, Naturalistic and native restoration plantings
- Wildlife
- Larval host plant for monarch and queen butterflies; nectar source for butterflies, bees and other pollinators. Stems and foliage exude toxic latex that deters most browsers.
- Toxicity
- Toxic if ingested; milky sap contains cardiac glycosides and can cause irritation and poisoning in humans, pets and livestock. Sap may irritate skin and eyes.
How to grow Desert Milkweed in Tucson & the low desert
Watering
Drought tolerant once established; water deeply but infrequently, roughly every 2-3 weeks in summer and rarely in winter. Overwatering causes weak, leggy growth and root rot.
Fertilizer & nutrients
No fertilizer needed; thrives in lean desert soils. Avoid feeding, which only produces rank growth.
Pruning & care
Little pruning required. Cut back leggy or frost-damaged stems in early spring to rejuvenate; the leafless rush-like green stems perform photosynthesis, so retain them.
Notes
Distinctive leafless, blue-green rush-like upright stems; one of the best heat- and drought-adapted milkweeds for low-desert Tucson landscapes and a key monarch host.
Sources: University of Arizona Cooperative Extension; Arizona-Sonora Desert Museum; AMWUA Landscape Plants for the Arizona Desert; Tohono Chul / Tucson Botanical Gardens