Antelope horns.

At a glance

Care level

Easy

Plant type

Perennial

Light

Full sun

Indoor light

Direct sun

Water

Every 7 to 14 days

Mature size

1 to 2 feet

Growth rate

Medium

Hardiness

USDA 5 to 9

Bloom time

Mid to late spring

Care

Plant this in a spot with excellent drainage to prevent root rot. Keep an eye out for aphids on the flower clusters, which are common but usually harmless. It is very drought tolerant once established, so avoid overwatering.

Watering

Water deeply when the soil is completely dry, but be careful not to let it sit in soggy ground.

Feeding

This plant generally does not need fertilizer and prefers lean soil.

Pruning

Cut back dead foliage in late winter to make room for new spring growth.

Repotting

It has a deep taproot, so it prefers to stay in the ground rather than being moved.

Soil

Sandy or rocky, well draining soil

Soil pH

6.0 to 8.0

Temperature

-25 to 40°C

Humidity

10 to 50%

Safety

People

The milky sap contains cardiac glycosides that can cause skin irritation and severe illness if ingested.

Pets

This plant contains cardiac glycosides and is toxic to cats and dogs if ingested.

Children

Keep this plant away from small children as the milky sap is toxic and can cause irritation if touched or ingested.

Contact allergens

The milky latex sap can cause contact dermatitis or eye irritation in sensitive individuals.

Airborne allergens

There is no significant evidence that this plant causes respiratory allergies.

Edibility

All parts of this plant are toxic if ingested and should not be consumed by humans or pets.

How to identify it

• Greenish yellow flowers in rounded clusters
• Curved, horn shaped seed pods
• Narrow, lance shaped leaves
• Low growing, clumping habit

Height

0.3 to 0.6m

Spread

0.3 to 0.6m

Leaves

green, gray-green, deciduous

Flowers

green, maroon, 5 to 8cm

Fruit

tan, late summer

Problems to watch for

• Aphids · Small insects that cluster on new growth and flower stalks.

Growing it

Propagation

seed

When to plant

spring, fall

Plant this in a sunny spot with well draining soil to keep it happy alongside other drought tolerant prairie natives.

Grows well with

• Little Bluestem · This grass provides a nice textural contrast and shares similar dry soil requirements.
• Purple Coneflower · They bloom around the same time and create a beautiful color combination.

Similar species

• Common Milkweed · It is a much larger, more aggressive plant that prefers slightly more moisture.

Science

Family

Apocynaceae

Genus

Asclepias

Order

Gentianales

Class

Magnoliopsida

Native range

Central and Southwestern United States.

Conservation

This species is not currently endangered or protected.

It survives in harsh, dry environments by developing a deep taproot that reaches moisture far below the surface.

Value to wildlife

larval host plant, nectar source

Pollinators

bees, butterflies, moths

Uses

pollinator garden, xeriscaping, native plant restoration

Taxonomy resolved against GBIF.

Questions people ask

Does it need a lot of water?

No, it is very drought tolerant once established.

Will it attract Monarchs?

Yes, it serves as a host plant for Monarch butterfly caterpillars.

Where the name comes from

The name Asclepias honors the Greek god of medicine, while asperula refers to the rough texture of the leaves.

Good to know

• It is commonly called Antelope Horns because the seed pods resemble the horns of an antelope.
• It thrives in rocky, dry soils where many other plants struggle.
• The flowers are highly fragrant, especially in the evening.

Also in

• Plants toxic to cats and dogs