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7 Irresistible Twin Falls, ID Milkweeds (Asclepias spp.) to Grow for Butterflies

General Information about Native Plant and Pollinator Gardens

When planting a native plant and pollinator garden in Twin Falls, ID, you need to ensure that you have a selection of plants that provide blooms at different times of the year. In addition to the plants, you need to provide a source of water such as a birdbath or water feature, shelter for animals, and nesting locations for birds. Be sure to also include plants of different heights for perching. Resources you can use for more information on butterfly gardening in Twin Falls, ID include the Idaho Land Conservation Assistance Network, the Idaho Department of Fish and Game – Backyards for Wildlife (.pdf), and Living Earth LLC..

Location of Twin Falls, Idaho

Idaho Falls in red on a map of Idaho.
Map of Idaho with Twin Falls in Red — Arkyan, CC BY-SA 3.0, via Wikimedia Commons

Twin Falls is located in southern Idaho at the north end of Twin Falls County.

USDA Plant Hardiness Zones in Twin Falls, Idaho

2023 USDA plant hardiness zone map for the state of Idaho.
2023 Idaho USDA Plant Hardiness Zone Map — USDA Public Domain

Twin Falls, ID is located at the edge of Plant Hardiness Zone 7a. When selecting plants in the city of Twin Falls you will want to get those that can handle temperatures as cold as 00F. Other parts of Twin Falls County will range from 00F to -150F depending on your hardiness zone.

Butterflies in Twin Falls, Idaho that are Hosted by Milkweeds (Asclepias spp.)

Monarch butterfly on green flower.
Green Flower with Monarch Butterfly (Danaus plexippus) — U.S. Fish and Wildlife Service, Public domain, via Wikimedia Commons

Monarch Butterfly (Danaus plexippus)

The monarch butterfly is an iconic butterfly in North America and is a bell-weather of the environment. Having a distinctive orange color with black stripes, this butterfly has a wingspan of 3 in (7.6 cm) to 5 in (12.7 cm). The monarch butterfly uses milkweed to get cardenolides, a toxin that is distasteful to predators. This butterfly can have several flights a year and is known for its migrations to Mexico each year. However, some populations in California, Arizona, and Florida do not migrate and breed year-round (Urguhart, et al 1968).

List of Milkweeds that are Native or Nearly Native in the Twin Falls, ID Area

1. Spider Milkweed (Asclepias asperula), a Milkweed for Dry Soils

If you are able to keep your plants watered and need a fairly short milkweed, spider milkweed may be for you. The short stature of the plant may make this plant suitable for growing in a container. Other companion plants for spider milkweed include showy milkweed (Asclepias speciosa), butterfly weed (Asclepias tuberosa), and rush milkweed (Asclepias subulata). These plants in addition to a selection of nectar plants can turn your garden into a pollinator buffet.

Plant of spider milkweed (Asclepias asperula) with white flowers.
Spider Milkweed (Asclepias asperula) — Patrick Alexander from Las Cruces, NM, CC0, via Wikimedia Commons

Facts about Spider Milkweed

  • Native to Idaho: Yes, one county in southeast Idaho (Kartesz 2015)
  • Native to Twin Falls County: No
  • Natural Habitat: areas that are open, dry and rocky or sandy including pastures, desert shrub and swales
  • Height: 1 ft (0.3 m) to 3 ft (0.9 m)
  • Flower Color: Yellowish-green with a dark purple hood
  • Flowering Period: April to June
  • USDA Hardiness Zone: 5-9

Gardening with Spider Milkweed

2. Pallid Milkweed (Asclepias cryptoceras), a Milkweed for Dry Sandy/Rocky Soils

Pallid milkweed is native to the Twin Falls area and is a small plant that is also suitable for containers and small plants. Just be sure to have full sun and a dry/rocky soil.

Yellowish flowers of pallid milkweed (Asclepias cryptoceras) in a desert.
Pallid Milkweed (Asclepias cryptoceras) — Patrick Alexander from Las Cruces, NM, CC0, via Wikimedia Commons

Facts about Pallid Milkweed

  • Native to Idaho: Yes, southwestern counties (Kartesz 2015)
  • Native to Twin Falls County: Yes
  • Natural Habitat: sandy washes and canyon bottoms (Jepson eflora) and talus slopes (Baker 1971)
  • Height: 0.4 ft (0.1 m) to 1 ft (0.3 m)
  • Flower Color: Yellowish-green (Woodson 1954) to cream-white (Heil, et al 2013)
  • Flowering Period: April to June
  • USDA Hardiness Zone: 6-10

Gardening with Pallid Milkweed

3. Narrow-leaf Milkweed (Asclepias fascicularis), a Milkweed for Well-drained Soils

Narrow-leaf milkweed is a good choice for those who have an open area with full sun exposure and well-drained soils. The narrow leaves add another texture to the garden that you do not often see.

Plant of narrow-leaf milkweed (Asclepias fascicularis) with yellow flowers.
Flowers of Narrow-leaf Milkweed — Asclepias fascicularis Decne. observed in United States of America by Lauren Gill (licensed under CC0 1.0)

Facts about Narrow-leaf Milkweed

  • Native to Idaho: Yes, scattered throughout except eastern counties (Kartesz 2015)
  • Native to Twin Falls County: No
  • Natural Habitat: grasslands, pastures, roadsides, disturbed areas, and woodlands
  • Height: 1 ft (0.3 m) to 3.5 ft (1.1 m)
  • Flower Color: grayish-pink to white (Woodson 1954), lavender to lavender-white (calscape.org), white and peach (Ljubenkov and Ross 2002), or greenish-white (Jepson eflora).
  • Flowering Period: May to October
  • USDA Hardiness Zone: 6-10

Gardening with Narrow-leaf Milkweed

4. Swamp Milkweed (Asclepias incarnata), a Milkweed for Moist Soils

If you have land that is wet or moist in Twin Falls, this milkweed may be for you.

Pink flowers of swamp milkweed (Asclepias incarnata) from Pennsylvania.
Flowers of Swamp Milkweed (Asclepias incarnata) — Cbaile19, CC0, via Wikimedia Commons

Facts about Swamp Milkweed

Asclepias incarnata subsp. incarnata in Idaho

  • Native to Idaho: Yes, central and southwestern counties (Kartesz 2015)
  • Native to Twin Falls County: Yes
  • Natural Habitat: shores of streams, lakes, ponds, and other wetlands
  • Height: 3 ft (0.9 m) to 5 ft (1.5 m)
  • Flower Color: pink or red
  • Flowering Period: July to September
  • USDA Hardiness Zone: 3-9

Gardening with Swamp Milkweed

5. Showy Milkweed (Asclepias speciosa), a Milkweed for Medium to Well-drained Soils

Showy milkweed is a plant in butterfly gardens around the United States. It is a small to medium sized plant, making it suitable for containers, but whether planted or in a container, it needs good drainage.

Pinkish-white flowers of showy milkweed (Asclepias speciosa).
Flowers of Showy Milkweed — Asclepias speciosa Torr. observed in Canada by markeambard (licensed under CC0 1.0)

Facts about Showy Milkweed

  • Native to Idaho: Yes, throughout (Kartesz 2015)
  • Native to Twin Falls County: Yes
  • Natural Habitat: roadsides, fields and woodlands
  • Height: 1 ft (0.3 m) to 3 ft (0.9 m)
  • Flower Color: purple to pink
  • Flowering Period: April to June
  • USDA Hardiness Zone: 3-9

Gardening with Showy Milkweed

6. Common Milkweed (Asclepias syriaca), a Milkweed for all Conditions

This milkweed is one of the most common in the midwest and northeastern United States. The large leaves provide ample feeding opportunities for monarch butterflies. While not native to Twin Falls, ID this species can handle the plant hardiness zone.

Common milkweed (Asclepias syriaca) with eastern tiger swallowtail.
Common Milkweed (Asclepias syriaca) with Eastern Tiger Swallowtail — Author Image

Facts about Common Milkweed

  • Native to Idaho: No (Kartesz 2015)
  • Native to Twin Falls County: No
  • Natural Habitat: grasslands, waste/disturbed lands, and roadsides
  • Height: up to 6 ft (1.8 m)
  • Flower Color: pink, greenish-purple, greenish-white to white
  • Flowering Period: June to August
  • USDA Hardiness Zone: 3-9

Gardening with Common Milkweed

7. Butterfly Weed (Asclepias tuberosa), a Milkweed for all Conditions

Butterfly weed is one of three milkweeds in the United States that has an orange coloered flower. In Twin Falls, ID this milkweed is at the upper limit of its hardiness zone and may experience heat stress in the future with climate change warming.

Orange flowers of butterfly weed (Asclepias tuberosa) in a garden.
Flowers of Butterfly Weed (Asclepias tuberosa) — Robert Coxe, Image

Facts about Butterfly Weed

  • Native to Idaho: No (Kartesz 2015)
  • Native to Twin Falls County: No
  • Natural Habitat: fields, roadsides and open woods
  • Height: 1 ft (0.3 m) to 3 ft (0.9 m)
  • Flower Color: orange
  • Flowering Period: June to October
  • USDA Hardiness Zone: 3-9

Gardening with Butterfly Weed

When selecting your Twin Falls, ID milkweed, be sure to make sure that it grows in your zone and habitat.

Books where you can find out more about Monarchs and Butterfly Gardening in Twin Falls, ID

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References for Twin Falls, ID Milkweeds

  • Ljubenkov, Julie A. and Timothy S. Ross. 2002. An Annotated Checklist of the Vascular Plants of the Whittier Hills, Los Angeles County, California. Crossosoma 27(1): 1-23.
  • Urguhart, Fredrick Albert, Norah Roden Urguhart, and Francis Munger. 1968. Population of Danaus plexippus in Southern California. Journal of Research on the Lepidoptera 7(4): 169-181.
  • Woodson, Robert E. 1954. The North American Species of Asclepias L. Annals of the Missouri Botanical Garden 41: 1-211.
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Robert Coxe

Robert Coxe

Robert Coxe is a professional ecologist and botanist who has worked as the State Ecologist of Delaware and as an ecologist for the Western Pennsylvania Conservancy. He is also a former Past-President of the Pennsylvania Academy of Science. He currently is an innkeeper at McMullen House Bed & Breakfast LLC and a web designer and owner for Silphium Design LLC.

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