Also known as Antelope Horns · Antelope Horns Milkweed · Immortal
Safety note: This plant may be toxic to humans and pets. See toxicity details.
Antelopehorn Milkweed (Asclepias asperula) is a striking perennial wildflower with twisted horns, crucial for monarch butterfly larvae. Thrives in arid to semi-arid condi
At-a-glance light, water, soil, and growing conditions from plant data
Full Sun
100% intensity
Requires at least 6-8 hours of direct sunlight daily for optimal growth and flowering.
Moderate to Low
50% intensity
Allow soil to dry out between waterings, especially once established. Drought tolerant.
Well-drained soil
50% intensity
Moderate to High
75% intensity
Tolerates a wide range of temperatures but thrives in warm to hot conditions during the growing season. Hardy in USDA zones 4-9.
Low
25% intensity
Requires minimal fertilization. Over-fertilizing can be detrimental. Lean soils are preferred.
Safety information from plant toxicity data
| Attribute | Value |
|---|---|
| Toxic for humans | Yes 5/5 intensity |
| Toxic for pets | Yes 5/5 intensity |
| Edible | No |
Contains cardiac glycosides
Key traits and growing stats from plant data
Watering, pruning, propagation, and repotting details from plant data
Water Asclepias asperula deeply when the soil is dry to the touch, typically once every 1-2 weeks during the growing season. Reduce watering significantly in fall and winter to prevent root rot.
Ensure well-draining soil to avoid waterlogged conditions, which this plant dislikes.
Prune Asclepias asperula in late winter or early spring before new growth emerges. Cut back dead or damaged stems to about 10-15 cm from the ground. This encourages robust new growth and maintains plant health.
Remove any spent flower stalks to prevent unwanted reseeding if necessary.
Propagate Asclepias asperula from seeds sown in fall or early spring. Stratification (cold treatment) improves germination. Seeds can also be started indoors 6-8 weeks before the last frost.
Division of established clumps in early spring is another effective method.
Repot Asclepias asperula only when necessary, typically every 2-3 years, or when the plant becomes root-bound. Choose a pot that is only slightly larger than the current one. Use a well-draining potting mix.
Repot in early spring before new growth begins.
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Monthly activity intensity for bloom and fruit across both hemispheres.
Flowering & fruiting calendar
Flowering & fruiting calendar
Photos of Antelopehorn Milkweed (Asclepias asperula)
Common names and botanical synonyms
Botanical classification
| Rank | Name |
|---|---|
| Kingdom | Plantae |
| Division | Tracheophyta |
| Class | Magnoliopsida |
| Order | Gentianales |
| Family | Apocynaceae |
| Genus | Asclepias |
| Species | Asclepias asperula |
Similar in genus Asclepias
Answers based on plant encyclopedia data
