Table of Contents for Twin Falls, ID Native or Nearly Native Milkweeds
There are seven species of native or nearly native Twin Falls milkweeds (Asclepias spp.) that can be grown for butterflies and other insects. Milkweeds are an important host species for monarch butterflies in Idaho. The monarch butterfly in particular uses the cardenolides found in the milky sap of milkweeds to give an unpleasant taste to predators. These plants are also an important nectar source to all insects visiting your pollinator garden.
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
Twin Falls is located in southern Idaho at the north end of Twin Falls County.
USDA Plant Hardiness Zones in Twin Falls, Idaho
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 (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.
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
In your Twin Falls, ID butterfly garden, this milkweed needs full sun and sandy/rocky soil. In the future, it may experience heat stress from climate induced warming, being at the top end of its hardiness zone.
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.
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
In your Twin Falls, ID butterfly garden, this milkweed needs full sun and dry/rocky sandy soils. Due to its rarity, this plant is not likely in the horticultural trade.
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.
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
In your Twin Falls, ID butterfly garden, this milkweed needs full sun and soils that are well-drained.
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.
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
In your Twin Falls, ID butterfly garden, this milkweed needs full sun to partial shade and medium to moist soil.
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.
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
In your Twin Falls, ID butterfly garden, this milkweed needs full sun and medium to well-drained soil.
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.
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
In your Twin Falls, ID butterfly garden, this milkweed needs full sun to part shade and soils that are well-drained to occasionally dry. While this species in not native to Idaho or the county, it can handle the plant hardiness zone and has been planted in adjacent states.
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.
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
In your Twin Falls, ID butterfly garden, this milkweed needs full sun and nearly any soil type. While this milkweed is not native to the area it can handle the plant hardiness zone.
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
- Daniels, Jaret C. 2022. Garden Bugs & Insects of the Northwest – Identify Pollinators, Pests, and Other Garden Visitors – Adventure Quick Guides. Adventure Publications. 36 pp.
- Daniels, Jaret C. 2020. Butterflies of the Northwest – Your Way to Easily Identify Butterflies – Advenute Quick Guides. Adventure Publications.
- Denver Botanic Gardens, Inc. 2024. Pollinators of the American West – A Field Guide to Over 300 Invertebrate Pollinators. Globe Pequot. 320 pp. (will be published in December 2024)
- Miller, George Oxford. 2024. Native Plant Gardening for Birds, Bees & Butterflies: Rocky Mountains – Nature Friendly Gardens. Adventure Publications. 280 pp. (will be published in July 2024)
- Parkinson. 2015. Landscaping With Native Plants of the Intermountain Region. Createspace. 54 pp.
- Pyle, Robert Michael and Caitlin C. LaBar. 2018. Butterflies of the Pacific Northwest – Timber Press Field Guide. Timber Press. 461 pp.
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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.
