Showy milkweed is a robust perennial that is pure magic for pollinators - especially butterflies. It’s pink, firework-shaped flowers are an incredible nectar source that attracts an array of bees and butterflies, it’s large blue-green leaves provide food for larval caterpillars, and the plant's alkaloid compounds boost butterflies' resistance to predators. In a region with relatively small populations of butterflies, due to our generally cloudy climate, Showy Milkweed supports our local butterflies, while rewarding us gardeners with glimpses of their elegance.
- Plant type/canopy layer: deciduous perennial herbaceous plant
- Size at maturity: 36" - 48", spreads laterally by rhizomes forming dense patches
- Light requirements: full to mostly sunny
- Moisture requirements: dry to moist, well-drained soil
- Bloom time: June - July
- Growth rate/ease: moderate growth rate, easy to grow
- Wildlife support: supports adult butterflies/nectar source, bees and other insect pollinators, beneficial insects/pest eating insects, caterpillar host plant/larval food source, hummingbirds (Oregon Flora Project)
- Native habitat/range: Valleys, roadsides, fields, disturbed areas up to 1600 meters in most areas of the state plus CA, ID, NV, WA; north to British Columbia, northeast to Manitoba, east to MI, southeast to TX. Portland Plant List - no.
- Special features & uses: important plant for pollinators, specifically butterflies
Gardening with Showy Milkweed: Showy Milkweed prefers sunny to partially-sunny conditions with dry, well-drained soils - but it can tolerate moisture and even seasonal flooding if the water is fast-draining. It can also handle some drought once established. It is generally intolerant of root disturbance and can be slow growing at first. But, once established, it spreads aggressively by rhizomes and may form dense colonies, particularly in roadside ditches and other wild areas.
Seed Sowing instructions: Direct sowing is not recommended. Showy milkweed seedlings are small and not vigorous in their first year. They are easily overtaken by other plants.Growing transplants: Seeds are not dormant but germinate best in warm temperatures (65-80 degrees). Seedlings will grow slowly the first summer in the containers, should be transplanted out into the landscape in fall when dormant, and will emerge again the following April. Each packet contains approximately 50 seeds collected in Benton County, Oregon.
Photo Credit 1: "Showy Milkweed (Asclepias speciosa) Seedskadee NWR" by USFWS Mountain Prairie is licensed under CC BY 2.0
Photo Credit 2: "Asclepias speciosa--RPBG--9 June 2007" by John Rusk is licensed under CC BY 2.0
Photo Credit 3: "Asclepias speciosa" by Matt Lavin is licensed under CC BY-SA 2.0