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.

Horsetail Milkweed

Name: Pollinator Patch
Author: Pollinator Patch

Asclepias subverticillata

Last reviewed: August 2026

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) 426-4435and 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.

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

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Browse plants for this ecoregion

Central Basin and Range North American Deserts Southern Rockies Arizona/New Mexico Mountains Chihuahuan Deserts High Plains Southwestern Tablelands Madrean Archipelago Sonoran Basin and Range

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.

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.

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