Slimleaf milkweed
Asclepias stenophylla
Last reviewed: November 2026
Slimleaf milkweed (Asclepias stenophylla) is a perennial forb native to AR, CO, IA, IL and 10 more states. It blooms in June, July, and August. The flowers draw bees and wasps.
Watering reminders and freeze alerts for Slimleaf milkweed, free in the app.
Slimleaf milkweed is toxic to dogs and cats.
Listed as toxic by the ASPCA Animal Poison Control Center (opens in new tab) (last reviewed 2026-08-15). If your pet has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435 and your veterinarian's emergency line.
The Pollinator Patch App flags toxic plants so you can choose a native alternative that is not on the ASPCA toxic plant list.
Native swaps for a yard with pets
Slimleaf milkweed is listed as toxic to dogs by the ASPCA Animal Poison Control Center. These natives fill a similar role in a planting and are not on the ASPCA toxic plant list for dogs or cats. Each plant's page carries its dated record.
Light
full sun
Water
low
Size
18"–36" H × 12"–18" W
Bloom
Jun, Jul, Aug
Native to
AR, CO, IA, IL and 10 more states
Pollinators
bees, wasps
Before you buy
Your city may pay you to plant this
Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 461 programs across 44 states, each with a link to the provider and the date we last checked it.
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Browse plants for this ecoregion
A slender prairie milkweed with narrow, grass-like leaves and rounded clusters of greenish-white flowers held close to the stem in summer. Its fine texture reads more like a wiry grassland forb than a typical broadleaf milkweed.
Growing Slimleaf milkweed
Grow Slimleaf milkweed in full sun and low water. Mature plants reach 18 to 36 inches tall and spread 12 to 18 inches wide.
Wildlife value
Host plant for monarch butterfly.
As a milkweed, it is an essential larval host plant for monarch butterflies, and its flowers also draw a range of native bees and wasps.
Common questions
- How much sun does Slimleaf milkweed need?
- Slimleaf milkweed grows best in full sun conditions.
- When does Slimleaf milkweed bloom?
- Slimleaf milkweed blooms in June, July, and August.
- Where is Slimleaf milkweed native?
- Slimleaf milkweed (Asclepias stenophylla) is native to AR, CO, IA, IL and 10 more states, per the World Checklist of Vascular Plants (Kew).
- Is Slimleaf milkweed toxic to dogs?
- Yes. Slimleaf milkweed is listed as toxic to dogs by the ASPCA Animal Poison Control Center (aspca.org). If your pet has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.
- Is Slimleaf milkweed toxic to cats?
- Yes. Slimleaf milkweed is listed as toxic to cats by the ASPCA Animal Poison Control Center (aspca.org). If your cat has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.
- What butterflies or moths does Slimleaf milkweed host?
- Slimleaf milkweed is a larval host plant for monarch butterfly.
Native range data from the World Checklist of Vascular Plants (Kew). Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
If something looks wrong
Common plant problems, and what to check first
These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.
- It is dying right after planting
- Leaves turning yellow
- Wilting even though I watered it
- Brown crispy leaf tips
- Bugs on the plant
Pollinator Patch flags toxic plants like Slimleaf milkweed and shows natives not flagged toxic to pets for your ecoregion instead.