List of California Milkweeds
California Milkweed Species to Include in your Butterfly Garden
There are fourteen species of native California milkweeds (Asclepias spp.) that can be grown for Monarch Butterflies and other insects. Another milkweed, tropical milkweed, is adventive to the state. 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.
1. White-stem Milkweed (Asclepias albicans), a Milkweed for Dry Soils
White-stem Milkweed (Asclepias albicans): White-stem milkweed is native to the southern counties of California (Kartesz 2015). In the wild, white-stem milkweed grows in dry areas such as deserts and gravelly, sparsely vegetated places. Growing from 4 to 12 feet tall, this milkweed is the tallest and one of the only shrubby milkweeds in North America. The greenish to white flowers bloom from September to June. It is hardy in zones 9-11.
In a California butterfly garden, this milkweed is hardy in zones 9-11 and requires full sun and sandy to rocky dry soils.
2. Spider Milkweed (Asclepias asperula), a Milkweed for Dry Soils
Spider Milkweed (Ascelpias asperula): Spider milkweed is native and rare to San Bernardino County (Kartesz 2015). Spider milkweed has two subspecies, one of which, subspecies asperula in California. In the wild, this milkweed grows in open areas that are dry rocky and/or sandy in desert scrub, swales, and pastures. Growing from 1 to 3 feet tall, the flowers are yellowish-green with a dark purple hood and bloom from April to June.
In a California butterfly garden, this milkweed is hardy in zones 5-9. Seeds of spider milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
3. California Milkweed (Asclepias californica), a Milkweed for Dry Sandy Soil
California Milkweed (Asclepias californica): California milkweed is native only to the state of California and adjacent areas of northern Mexico. It has two subspecies, subsp. californica, which is found in the southern counties of the state, and subsp. greenei, which is found in the central and northern counties of the state (Kartesz 2015). In the wild, California milkweed is grows in open areas with disturbance such as fields, pastures, and roadsides, and woodlands. Growing from 2 to 4 feet tall, the flower colors are widely variable and include white, pink, lavender, green, purple, or red and bloom from March to July.
In a California butterfly garden, this milkweed is hardy in zones 7-10, requires full sun and dry sandy or clay soils.
4. Heart-leaf Milkweed (Asclepias cordifolia), a Milkweed for Mesic to Dry Soils
Heart-leaf Milkweed (Asclepias cordifolia): Heart-leaf milkweed is native in the central and northern counties of California (Kartesz 2015). In the wild, heart-leaf milkweed grows in woodlands and talus slopes. Growing from 1 to 4 feet tall, the purple, lavender, to red flowers bloom from March to August.
In a California butterfly garden, heart-leaf milkweed is hardy in zones 7-10, requires full sun to partial shade and mesic to dry well-drained soil. Seeds of Heart-leaf Milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
5. Pallid Milkweed (Asclepias cyptoceras), a Milkweed for Dry Sandy/Rocky Soils
Pallid Milkweed (Asclepias cryptoceras): Pallid milkweed is native to two counties in the eastern part of the state (Kartesz 2015). In the wild, pallid milkweed grows in sandy washes and canyon bottoms (Jepson eflora), as well as, talus slopes (Baker 1971). Growing from 0.4 to 1 foot tall, the yellowish-green (Woodson 1954) to cream-white (Heil, et al 2013) flowers bloom from April to June.
In a California butterfly garden, this milkweed is hardy in zones 6-10, requires full sun and dry or rocky sandy soils.
6. Woollypod Milkweed (Asclepias eriocarpa), a Milkweed for Mesic to Dry Soils
Woollypod Milkweed (Asclepias eriocarpa): Woollypod milkweed is native throughout the state (Kartesz 2015). In the wild, woollypod milkweed grows in dry areas with full sun including deserts, roadsides, fields, and rocky hillsides. Growing from 2 to 4 feet tall, the greenish to yellowish-white (Woodson 1954) or pink (Calscape) flowers bloom from May to October.
In a garden setting, this plant is hardy in zones 4-9, requires full sun to partial shade and mesic to dry well-drained soil. Seeds of woollypod milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
7. Desert Milkweed (Asclepias erosa), a Milkweed for Dry Sandy Soils
Desert Milkweed (Asclepias erosa): Desert milkweed is native to the central and southern counties of California (Kartesz 2015). In the wild, desert milkweed grows in washes, roadsides, and sandy plains. Growing from 1 to 4 feet tall, the white, cream, green, to yellow flowers bloom from April to October.
In a California butterfly garden, this milkweed is hardy in zones 4-10, require full to partial sun and dry sandy soils. Seeds for desert milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
8. Narrow-leaf Milkweed (Asclepias fascicularis), a Milkweed for Poor Well-drained Soils
Narrow-leaf Milkweed (Asclepias fascicularis): Narrow-leaf milkweed is native throughout California (Kartesz 2015). In the wild, narrow-leaf milkweed grows in dry open areas such as grasslands, roadsides, woodlands, and disturbed areas. Growing from 1 to 3.5 feet, the grayish-pink to white (Woodson 1954), lavender (Calscape), white to peach (Ljubenkov and Ross 2002) or greenish-white (Jepson eflora) flowers bloom from May to October.
In a California butterfly garden, this milkweed is hardy in zones 6-10, requires full sun and poor well-drained soils. Seeds of narrow-leaf milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
9. Broad-leaf Milkweed (Asclepias latifolia), a Milkweed for Dry Soils
Broad-leaf Milkweed (Asclepias latifolia): Broad-leaf milkweed is native in the eastern counties of California (Kartesz 2015). In the wild, broad-leaf milkweed grows in dry open areas such as prairies, roadsides, and other right-of-ways. Growing from 1 to 3 feet tall, the greenish to yellow flowers bloom from May to August.
In a California butterfly garden, this milkweed is hardy in zones 5-8, requires full to partial sun and dry sandy soils. Seeds of broad-leaf milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
10. Mojave Milkweed (Asclepias nyctaginifolia), a Milkweed for Dry Sandy Soils
Mojave Milkweed (Asclepias nyctaginifolia): Mojave milkweed is native and rare in San Bernandino County (Kartesz 2015). In the wild, mojave milkweed grows in a variety of generally dry open places such as washes and hillsides, roadsides, open woodlands, and grasslands. Growing from 0.5 to 1.75 feet tall, the greenish-white to greenish-yellow flowers bloom from April to October.
In a California butterfly garden, this milkweed is hardy in zones 7-9, requires full sun and dry sandy soils.
11. Serpentine Milkweed (Asclepias solanoana), a Milkweed for Serpentine Geology
Serpentine Milkweed (Asclepias solanoana): Serpentine milkweed is native and rare in the northern counties of California (Kartesz 2015). In the wild, serpentine milkweed grows in open woodlands and rocky outcrops of serpentine. Growing from 0.3 to 1 foot tall, the red, purple, to white flowers bloom in June.
In a California butterfly garden, this milkweed is hardy in zones 7-9, requires full sun and a specific geological rock called serpentine. This plant is not known to be in cultivation because of the specific geology required.
12. Showy Milkweed (Asclepias speciosa), a Milkweed for Mesic to Dry Soil
Showy Milkweed (Asclepias speciosa): Showy milkweed is native in the central and northern counties of the state (Kartesz 2015). In the wild, showy milkweed grows in open areas such as roadsides, fields, and woodlands that are mesic to dry. Growing from 1 to 3 feet tall, it has flowers that are purple to pink in color and bloom from April to June.
In a garden setting, this plant is hardy in zones 3-9, requires full sun and soils that mesic to dry. Seeds of showy milkweed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
13. Rush Milkweed (Asclepias subulata), a Milkweed for Dry Soils
Rush Milkweed (Asclepias subulata): Rush milkweed is native to the southern counties of California (Kartesz 2015). In the wild, rush milkweed grows in open areas with full sun such as washes and arroyos (Jepson eflora), benches of slopes (Roberts, et al 1998) desert areas (Shreve 1936), sandy flats (McLaughlin 1987), and roadsides (Felger 2014). Growing from 3 to 6 feet this plant has flowers that are yellowish-white to cream that bloom year-round.
In a California butterfly garden, this milkweed is hardy in zones 9-11, requires full sun and dry sandy/gravelly soils.
14. Woolly Milkweed (Asclepias vestita), a Milkweed for Well-drained Soils
Woolly Milkweed (Asclepias vestita): Woolly milkweed is native to the central and southern counties of California (Kartesz 2015). In the wild, woolly milkweed grows in dry plains, canyons, and chaparral. Growing from 1.5 to 3 feet tall, this plant has yellowish-white or greenish-white flowers with a purple tint that bloom from April to July.
In a California butterfly garden, this milkeed is hardy in zones 7-10, requires full sun and well-drained soils.
Additional Milkweeds in California that are not Native
1. Butterfly Weed (Asclepias tuberosa)
Butterfly Weed (Asclepias tuberosa): Buttefly weed is one of the most common for butterfly gardeners on the east coast of the United States. In California, it essentially occurs throughout the state, except it is scattered in the northwest. The flowers are characteristically orange and bloom throughout the summer and sometimes into the autumn. It grows in open areas with full sun such as fields, roadsides, and open woods and is hardy from zones 3-9. Seeds of butterfly weed can be purchased in the McMullen House Bed & Breakfast Garden Shop.
2. Tropical Milkweed (Asclepias curassavica)
Tropical Milkweed (Asclepias curassavica): Tropical milkweed is adventive (not native, but naturalized) in the southern parts of the state (Kartesz 2015). The flowers, which bloom from June to October, are colored bright orange, yellow, or red. Tropical milkweed is planted in gardens and other disturbance places. It is hardy in zones 8-11.
3. African Milkweed (Asclepias fruticosa)
African Milkweed (Asclepias fruticosa): African milkweed is exotic in the central and southern coastal counties of the state (Kartesz 2015). The flowers, which bloom from December to July, are colored white or pink. African milkweed is planted in gardens and other disturbance places, but according the Jepson flora (Jepson eflora) it is not spreading. It is hardy in zones 8-11.
When selecting your California milkweed, be sure to make sure that it grows in your zone and habitat.
References for California Milkweeds
- Baker, William H. 1971. Noteworthy Records of Western Plants. Madrono 21: 199-200.
- Heil, Kenneth D., Steve L. O’Kane, Linda Mary Reeves, and Arnold Clifford. 2013. Flora of the Four Corners Region: Vascular Plants of the San Juan River Drainage, Arizona, Colorado, New Mexico, and Utah. Monographs on Systematic Botany – Missouri Botanical Garden v. 124.
- 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)]
- 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.
- McLaughlin, Steven P., Janice E. Bowers, and Kenneth R.F. Hall. 1987. Vascular Flora of Eastern Imperial County, California. Madrono 34: 359-378.
- Roberts, Fred M., Grant Fletcher, Steve Boyd, Andrew C. Sanders, Peter Lesica, Peter Husby, Stephen V. Cooper,and Job Kuijt. 1998. Noteworthy Collections. Madrono 45: 326-330.
- Shreve, Forrest. 1936. The Transition from Desert to Chaparral in Baja California. Madrono 3: 257-264.
- Woodson, Robert. 1954. The North American Species of Asclepias L. Annuals of the Missouri Botanical Garden 41: 1-211.
