Green Antelopehorns

Year-round

Green antelopehorn milkweed is a low, clump-forming perennial from dry prairies and roadsides across the central and eastern United States. It is documented as native to Texas broadly, but it is not specifically confirmed in the El Paso area or the Chihuahuan Desert borderlands, so treat it here as an adapted dryland perennial rather than a locally native one.

• Plant in full sun in fast-draining soil. It tolerates poor, rocky, or limestone-based soil and does not need amending in El Paso's alkaline ground.
• Give it occasional deep water through the hottest months rather than frequent shallow watering. Lady Bird Johnson Wildflower Center lists it as a low-water-use plant.
• Milkweeds in the Asclepias genus, including this species, are the required host plant for monarch caterpillars. Leave some plants unclipped through the growing season so caterpillars can feed.
• All parts of milkweed contain compounds the ASPCA lists as toxic to dogs, cats, and horses. Site it away from areas pets chew on and rinse hands after handling cut stems.

Fall

Fall brings milder temperatures and El Paso's longest stretch of reliable dry weather, a good time to leave seed heads standing and reduce watering as the plant heads toward winter dormancy.

• Cut back watering to every 3 to 4 weeks as temperatures drop after October.
• Leave dried stems and pods standing through fall. They release seed over time and offer some shelter for overwintering insects.
• This is a good window to divide and transplant established clumps, since the plant is not actively flowering.
• El Paso's first frost typically arrives around mid-November. Stop fertilizing at least six weeks before it.

Winter

This milkweed dies back to the ground in winter and relies on its taproot to survive El Paso's cold snaps, needing little from a caregiver besides patience.

• Do not water on a regular schedule in winter. The dormant crown needs almost no supplemental moisture.
• Leave the dead stalks in place rather than cutting them to the ground. They mark the plant's location and offer a small amount of frost buffering for the crown.
• El Paso's zone 8a to 8b winters typically bottom out between 10 and 20 degrees Fahrenheit, with occasional harder freezes in an unusual winter. A dormant, well-rooted plant should tolerate this without protection.
• Wait until new growth appears in spring, often not until April, before assuming a clump is dead.

Spring

Spring is the natural bloom window for green antelopehorn milkweed in the Southwest, and in El Paso's dry, windy spring this is also when new growth needs the most consistent moisture to get established.

• Water newly planted or divided clumps twice a week through March and April while roots establish, then taper off.
• Expect flowering to begin in April, among the earliest milkweeds to bloom, so watch new growth for butterfly eggs.
• El Paso's spring dust storms and wind can dry out young leaves fast. A layer of gravel mulch around the base helps hold soil moisture without trapping stem rot.
• Established clumps are slow to emerge. Do not assume a plant is dead if it has not leafed out by mid-March, wait until late April before replacing it.

Its low, tidy clumping habit under two feet reads as an HOA-friendly front-bed perennial once established.

Summer

Summer in El Paso means long stretches of triple-digit heat and very low humidity, conditions this milkweed tolerates well once established, but young or thirsty plants can go dormant early if the soil dries out completely for too long.

• Deep-water every 10 to 14 days during peak summer heat, more often for plants in their first year.
• Seed pods form after bloom. Let a few mature and split for self-seeding if you want more plants, or remove them for a tidier look.
• This species often dies back to the crown by mid to late summer even with water. That is normal here, not a sign of disease.
• Water at soil level in the early morning rather than overhead in the afternoon, to cut down on evaporation loss.