Milkweed in Oregon
Showy milkweed dominates the Willamette Valley and the state’s eastern high desert, while narrowleaf milkweed occupies southern Oregon’s drier valleys and heartleaf milkweed climbs into the Siskiyou foothills. Oregon is a critical spring corridor for western monarchs leaving the California coast.
The best milkweed to plant in Oregon
Native to the state, garden-worthy and useful to monarchs. Start here if you are planting rather than identifying.
All milkweed species in Oregon
| Species | Height | Flower | Bloom | Soil | Monarch |
|---|---|---|---|---|---|
| Showy Milkweed Asclepias speciosa |
2 ft–5 ft | pink, rose | May to August | Average / Dry | |
| Narrowleaf Milkweed Asclepias fascicularis |
2 ft–4 ft | white, pink, green | May to September | Dry / Average | |
| Heartleaf Milkweed Asclepias cordifolia |
1 ft–3 ft | maroon, purple | May to July | Dry | |
| Pallid Milkweed Asclepias cryptoceras |
4 in–1 ft | cream, pink | April to June | Dry |
Planting milkweed in Oregon
Sow seed outdoors in October to December, so the seed uses winter rain. Winter then supplies the cold-moist stratification most milkweed seed needs, and germination happens naturally as the soil warms. If you have missed that window, chill seed in the refrigerator for 30 days and sow after your last frost. The full method is here.
Oregon spans USDA zones 4a–9b, so check the zone range on each species page before committing. Match the species to your site rather than the other way round: dry, sunny and poor suits butterfly weed and the whorled species; a damp spot suits swamp milkweed; shade suits very few milkweeds at all.
Plant at least ten stems in one group rather than scattering them, because female monarchs find dense patches far more readily. Add late-season nectar such as goldenrod and asters so the fall migratory generation has fuel as well as host plants. How to lay out a monarch garden.
Where to buy milkweed in Oregon
Start with Native Plant Society of Oregon. State native plant societies run the plant sales worth going to: locally grown, untreated stock, at a few dollars a plant, sold by people who can tell you where to put it.
In Oregon
Independent Portland nursery growing Pacific Northwest natives.
Elsewhere in the pacific
California native plant non-profit with a nursery, a seed program and a well-known plant sale.
Independent California native seed house.
Independent California native nursery with unusually detailed species notes.
Independent southern California native plant nursery.
Independent Bay Area nursery growing local-provenance natives.
Ships to you
One of the widest milkweed seed and bare-root ranges anywhere, with germination codes listed for every species.
Long-established independent nursery specializing in Midwestern natives.
Independent seed producer supplying restoration-scale native seed by the pound.
Family-run native seed producer for the eastern and central states.
Family-run Texas seed house focused on regional ecotypes.
These favor independent nurseries and non-profits over chain garden centers, which mostly stock unlabeled tropical milkweed and often cannot tell you whether it has been treated with neonicotinoids. Search the full directory by ZIP code.
Milkweed in Oregon: common questions
What milkweed is native to Oregon?
4 milkweed species are recorded in Oregon, including Showy Milkweed (Asclepias speciosa), Narrowleaf Milkweed (Asclepias fascicularis), Heartleaf Milkweed (Asclepias cordifolia), Pallid Milkweed (Asclepias cryptoceras). The full list is on this page.
What is the best milkweed to plant in Oregon?
Showy Milkweed, Narrowleaf Milkweed, Heartleaf Milkweed are the best combination of native, available and garden-worthy for Oregon. Showy Milkweed is the easiest to start with.
When should I plant milkweed seed in Oregon?
Sow outdoors in October to December, so the seed uses winter rain, so winter provides the cold stratification the seed needs. If you have missed that window, stratify seed in the refrigerator for 30 days and sow in spring after the last frost.
Does milkweed grow wild in Oregon?
Yes. 4 species occur in Oregon, typically on roadsides, field margins, prairie remnants and along watercourses. Showy milkweed dominates the Willamette Valley and the state’s eastern high desert, while narrowleaf milkweed occupies southern Oregon’s drier valleys and heartleaf milkweed climbs into the Siskiyou foothills.
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Milkweed USA. (2026). Milkweed in Oregon. Retrieved DATE, from https://milkweedusa.com/states/oregon/
"Milkweed in Oregon." Milkweed USA, 2026, https://milkweedusa.com/states/oregon/. Accessed DATE.
Milkweed USA. "Milkweed in Oregon." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/states/oregon/.
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year = {2026},
url = {https://milkweedusa.com/states/oregon/},
note = {Accessed DATE}
}