List of Iowa Milkweeds
Iowa Milkweed Species to Include in your Butterfly Garden
There are seventeen native species of Iowa milkweeds (Asclepias spp.) that can be grown for Monarch Butterflies and other insects. Milkweeds are an important host species for Monarch, Queen, and Soldier Butterflies. 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.
List of Native Iowa Milkweeds
1. Clasping Milkweed (Asclepias amplexicaulis), a Milkweed for Dry Soils
Clasping Milkweed (Asclepias amplexicaulis): Clasping milkweed is native mostly in eastern Iowa with scattered locations in the west (Kartesz 2015). In the wild, Clasping milkweed grows in dry woodlands, prairies, meadows, and roadsides having sandy or gravelly soil. Growing up to 3 feet tall, this plant has greenish-pink, red, brown, to purple flowers that bloom from March to September.
In Iowa butterfly garden, clasping milkweed is hardy in zones 3-9 and can be grown in places with full sun to part-shade having dry sandy soil. Seeds of clasping milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
2. Engelmann’s Milkweed (Asclepias engelmanniana), a Milkweed for Dry Soils
Engelmann’s Milkweed (Asclepias engelmanniana): Englemann’s milkweed is native and rare in three western counties in Iowa (Kartesz 2015). In the wild, Engelmann’s milkweed grows in dry prairies, plains, canyons, on creek banks, and open woodlands. Growing from 2 to 5 feet tall, this plant has greenish-yellow to purplish flowers that bloom from May to September.
In your Iowa butterfly garden, Engelmann’s milkweed requires full sun, dry sandy or limestone soils and is hardy in zones 5-9. Seeds of Engelmann’s milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
3. Poke Milkweed (Asclepias exaltata), a Milkweed for Shade and Moist Soil
Poke Milkweed (Ascelpias exaltata): Poke milkweed is native generally in eastern Iowa (Kartesz 2015). In the wild, this milkweed is found moist woods, roadsides, and the edges of woods. Growing 2 to 6 feet tall, it is one of the taller milkweeds, and has flowers that are white to green with accents of rose, purple, or blue. The flowers bloom from April to August.
In your Iowa butterfly garden, poke milkweed is hardy in zones 3-9, requires part-shade to shade, and moist soil. Poke milkweed seeds can be purchased in the McMullen House Bed & Breakfast Garden Shop.
4. Swamp Milkweed (Asclepias incarnata), a Milkweed for Moist Soils
Swamp Milkweed (Asclepias incarnata): Swamp milkweed has two subspecies, ssp. incarnata and ssp. pulchra. The former is found throughout the state (hardy in zones 3-9), while the latter is not found in Illinois (Kartesz 2015). Like the name suggests in the wild, swamp milkweed is found in wet places such as the shores of streams, lakes, ponds, and other wetlands. This is one of the taller milkweeds growing from 3 to 5 feet tall. The flowers, which bloom from July to September are generally a pink to red color, but there is also a white cultivar (pictured below).
In Iowa butterfly garden, swamp milkweed requires full sun to part-shade and prefers moist to medium moisture soil, but can exist in drier soil as a landscape plant. Seeds of swamp milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
5. Side-Cluster Milkweed (Asclepias lanuginosa), a Rare Iowa Milkweed
Side-cluster Milkweed (Asclepias lanuginosa): Side-cluster milkweed is native and rare in scattered locations around Iowa (Kartesz 2015). In the wild, Side-cluster milkweed grows in prairies and sandhills having full sun. The height of this milkweed is variable and ranges from 0.5 to 4 feet tall. The flowers range in color from green to cream and bloom from May to July.
In your Iowa butterfly garden, while side-cluster milkweed is hardy in zones 4-7, it is rare throughout most its range and is not in the horticultural trade.
6. Long-leaf Milkweed (Asclepias longifolia), a Milkweed for Moist Soils
Long-leaf Milkweed (Asclepias longifolia): Long-leaf milkweed has two varieties, var. hirtella and var. longifolia. Of these var. hirtella is native mostly in eastern Iowa (Kartesz 2015). In the wild, long-leaf milkweed grows in moist areas and wetlands such as bogs, swamps, flatwoods, and prairies having full sun. Growing from 1 to 2.5 feet tall, the greenish-white flowers bloom from April to July.
In your Iowa butterfly garden, long-leaf milkweed requires full sun, moist to wet soils and is hardy in zones 4-9.
7. Mead’s Milkweed (Asclepias meadii), a Rare Iowa Milkweed
Mead’s Milkweed (Asclepias meadii): Mead’s milkweed is native and rare in southwest and eastern Iowa (Kartesz 2015). In the wild, Mead’s milkweed grows in tallgrass prairies, hay meadows, and barrens having full sun. Growing from 1 to 3 feet tall, the greenish-white to yellow flowers bloom from June to July. This plant is federally endangered and is not in cultivation.
8. Oval-leaf Milkweed (Asclepias ovalifolia), a Milkweed for Well-drained High pH Soil
Oval-leaf Milkweed (Asclepias ovalifolia): Oval-leaf milkweed is native to scattered locations in the state (Kartesz 2015). In the wild, oval-leaf milkweed grows in open areas having full sun or partial shade such as prairies, grasslands, savannas, railroad edges, and alluvial terraces. It is one of the shorter milkweeds in Iowa and grows to about 2 feet tall and has white, pink, or green flowers that bloom from May to August.
In your Iowa butterfly garden, oval-leaf milkweed is hardy in zones 5-9, requires full sun to part-shade and well-drained high pH soil. Oval-leaf milkweed seeds can be purchased in the McMullen House Bed & Breakfast Garden Shop.
9. Purple Milkweed (Asclepias purpurascens), a Milkweed for Moist Soils
Purple Milkweed (Asclepias purpurascens): Purple milkweed is native in eastern, central, and southern Iowa (Kartesz 2015). In the wild, purple milkweed grows in moist to dry places having full sun to part shade such as swamps, woodlands, meadows, roadsides, and dry fields. Growing up to 6 feet tall the purple to pink flowers bloom from May to July.
In your Iowa butterfly garden, purple milkweed is hardy in zones 3-8 and requires part-shade but can handle full sun. Soils should be moist and well-drained, but dry soil can be tolerated. Seeds of purple milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
10. Four-leaf Milkweed (Asclepias quadrifolia), a Milkweed for Dry Rocky Soils
Four-leaf Milkweed (Asclepias quadrifolia): Four-leaf milkweed is native primarily in southeastern Iowa, with a scattered distribution in the south central area (Kartesz 2015). In the wild, four-leaf milkweed grows in open places with full sun such as roadsides, pastures, and prairies. Growing from 1 to 3 feet tall, four-leaf milkweed has cream to pink flowers that bloom from April to July.
In your Iowa butterfly garden, four-leaf milkweed is hardy in zones 5-8 and grows best in places of full sun to part-shade with dry rocky soils.
11. Showy Milkweed (Asclepias speciosa), a Milkweed for Medium to Dry Soils
Showy Milkweed (Asclepias speciosa): Showy milkweed is native and rare in the northwestern part of the state (Kartesz 2015). In the wild, Showy milkweed grows in open places with full sun such as fields, roadsides, and woodlands that are mesic to dry. Growing from 1 to 3 feet tall, this plant has purple to pink flowers that bloom from April to June.
In your Iowa butterfly garden, showy milkweed is hardy in zones 3-9 and requires places of full sun having medium to dry well-drained soil. Seeds of showy milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
12. Slim-leaf Milkweed (Asclepias stenophylla), a Milkweed for Dry Soils
Slim-leaf Milkweed (Asclepias stenophylla): Slim-leaf milkweed is native and rare in the western part of the state (Kartesz 2015). In the wild, Slim-leaf milkweed grows in open areas with full sun such as prairies and sandy areas. Growing from 0.5 to 3 feet tall, this milkweed has greenish-white flowers that bloom from June to August.
In your Iowa butterfly garden, slim-leaf milkweed is hardy in zones 3-9, requires full sun, and dry sandy or gravelly soils. Seeds of slim-leaf milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
13. Sullivant’s Milkweed (Asclepias sullivantii), a Milkweed for Medium to Dry Soils
Sullivant’s Milkweed (Asclepias sullivantii): Sullivant’s milkweed is native throughout the state (Kartesz 2015). In the wild, Sullivant’s milkweed grows in open areas with full sun such as prairies, meadows, roadsides, and railroads. Growing from 2 to 5 feet tall, it has pink to purplish flowers the pink to purplish flowers that bloom from June to July.
In your Iowa butterfly garden, Sullivant’s milkweed is hardy in zones 3-7, requiring full sun and medium to dry sandy soil. Seeds of Sullivant’s milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
14. Common Milkweed (Asclepias syriaca), a Milkweed for all Conditions
Common Milkweed (Asclepias syriaca): Common milkweed is native throughout the state (Kartesz 2015). In the wild, common milkweed is found in open areas such as fields, pastures, and roadsides, where it can receive full sun. One of the taller milkweeds, it can grow up to 6 feet tall and has flowers ranging from pink, greenish-purple, greenish-white, to white that bloom from June to August.
In your Iowa butterfly garden, common milkweed is hardy in zones 3-9 and grows in almost any exposure and soil condition, though it prefers full sun. Seeds of common milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
15. Butterfly Weed (Asclepias tuberosa), a Milkweed for all Conditions
Butterfly Weed (Asclepias tuberosa): Butterfly weed is one of the most common for butterfly gardeners on the east coast of the United States. In Iowa, subspecies interior of this species is native throughout the state (Kartesz 2015). In the wild, butterfly weed grows in open areas with full sun such as fields, roadsides, and open woods. Growing from 1 to 3 feet tall, the characteristically orange flowers bloom throughout the summer and sometimes into the autumn.
In your Iowa butterfly garden, it is hardy from zones 3-9 and grows in most conditions, but prefers full sun if possible. Seeds of butterfly weed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
16. Whorled Milkweed (Asclepias verticillata), a Milkweed for Medium to Dry Soils
Whorled Milkweed (Asclepias verticillata): Whorled milkweed is native throughout the state (Kartesz 2015). In the wild, whorled milkweed grows in open areas such as meadows and fields, where it can take advantage of full sun. Growing up to 3 feet tall, this milkweed has green to white flowers that bloom from May to September.
In your Iowa butterfly garden, whorled milkweed is hardy in zones 3-9, requires full sun to part-shade and medium to dry soil. Seeds of whorled milkweed can be purchased at the McMullen House Bed & Breakfast Garden Shop.
17. Green Comet Milkweed (Asclepias viridiflora), a Milkweed for Medium to Dry Soils
Green Comet Milkweed (Asclepias viridiflora): Green comet milkweed is native throughout Iowa (Kartesz 2015). In the wild, green comet milkweed grows in open areas such as meadows and field where there is full sun. Growing up to 3 feet tall, it has flowers that start out green color but age to become yellow and purple tinged. The flowers bloom from June to August.
In your Iowa butterfly garden, it is hardy in zones 3-9, requires full sun to part-shade, and medium to dry sandy soil. Seeds of green comet milkweed can be purchased at the McMullen House Bed & Breakfast Garden Shop.
When selecting your Iowa milkweed, be sure to make sure that it grows in your zone and habitat.
References for Iowa Milkweeds
- Kartesz, J.T. The Biota of North America Program (BONAP). 2015. Taxonomic Data Center. Link to website. Chapel Hill, N.C. [maps generated from Kartesz, J.T. 2015. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP). (in press)]