Horsetail Milkweed
Asclepias subverticillata
Last reviewed: October 2026
Horsetail Milkweed (Asclepias subverticillata) is a perennial forb native to AZ, CO, KS, MO and 5 more states. It blooms in June, July, August, and September. The flowers draw bees, wasps, and butterflies.
Horsetail 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.
Pollinator Patch flags toxic plants so you can choose a pet-safe native alternative for your yard.
Is Milkweed Toxic to Dogs? covers the symptoms, what to do after exposure, and safe native swaps.
Native swaps for a yard with pets
Horsetail 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
12"–36" H × 12"–24" W
Bloom
Jun, Jul, Aug, Sep
Native to
AZ, CO, KS, MO and 5 more states
Pollinators
bees, wasps, butterflies
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 459 programs across 44 states, each with a link to the provider and the date we last checked it.
Find rebates in your areaPicture natives in your own yard
Upload a photo of your yard and Patch Vision shows a rendering of it planted with natives for your region, like Horsetail Milkweed.
Browse plants for this ecoregion
An upright milkweed with narrow, whorled leaves in tight clusters along the stem and rounded umbels of small white flowers. Spreads by rhizomes to form loose colonies in open, dry ground.
Growing Horsetail Milkweed
Grow Horsetail Milkweed in full sun and low water. Mature plants reach 12 to 36 inches tall and spread 12 to 24 inches wide.
Wildlife value
Host plant for monarch.
A milkweed species that is a larval host plant for monarch butterflies, and its flowers are also a nectar source for bees and wasps. Note: this species is toxic to livestock and pets if ingested in quantity.
Common questions
- How much sun does Horsetail Milkweed need?
- Horsetail Milkweed grows best in full sun conditions.
- When does Horsetail Milkweed bloom?
- Horsetail Milkweed blooms in June, July, August, and September.
- Where is Horsetail Milkweed native?
- Horsetail Milkweed (Asclepias subverticillata) is native to AZ, CO, KS, MO and 5 more states, per vouchered herbarium specimen records and regional native plant society lists.
- Is Horsetail Milkweed toxic to dogs?
- Yes. Horsetail 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 Horsetail Milkweed toxic to cats?
- Yes. Horsetail 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 Horsetail Milkweed host?
- Horsetail Milkweed is a larval host plant for monarch.
Native range data from vouchered herbarium specimen records and regional native plant society lists. 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 Horsetail Milkweed and shows pet-safe natives for your ecoregion instead.