Purple Milkweed for Monarch Caterpillars and Beneficial Pollinators
Asclepias purpurascens common name: Purple milkweed
Purple Milkweed Plant Specs
- Perennial Zone: USDA hardiness zones 3a-9b (lows -40 °C or -40 °F)
- Native Plant: Most of the eastern US and Ontario Canada (Ar, Ct, De, DC, Ga, Il, In, Ia, Ks, Ky, La, Me, Md, Ma, Mi, Mn, Ms, Mo, Ne, NH, NJ, NY, NC, Oh, Ok, Pa, RI, SD, Tn, Tx, Va, WV, Wi, ON
- Plant full sun to part shade
- Height: 2 to 3 feet
- Spacing: 1 to 3 ft
- Leaves more pointed than asclepias syriaca (common milkweed) and a dark green color
- Flowers: rich rose to a light purplish color filled with nectar
- Blooms late spring to early summer
- Milkweed pods are smooth and thin compared to common milkweed
Asclepias Purpurascens Pros
- Preferred spring host plant for monarchs
- Not an aggressive spreader like its common counterpart
- Fragrant flowers are popular with pollinators
- Pretty purple flowers (in multiple shades) are some of milkweed’s finest
- Pretty purple blossoms illuminate the garden in late spring and early summer
- Easier to transplant successfully with no underground rhizome
Asclepias Purpurascens Cons
- Seeding can be an issue with mature plants
- More difficult to establish due to lack of an underground rhizome
- Difficult to find plants/seeds locally or online…get them when you have the opportunity!
- Prone to aphid pests like most milkweeds
- Fewer gardeners report growing this successfully, there is still more to learn about best growing practices
- Pest Favorite? After planting 7 plants last fall, they were all mowed to the ground by small critters (rabbits?) within two days.
Asclepias Purpurascens Plant Propagation
- Harvest Milkweed Seeds in Fall and then
- Sow seeds outside in fall– November is a good option for most regions
- Winter sowing milkweed seeds is a good option to control plant placement
- Start seeds indoors 2 months before final frost- seeds must be cold stratified
- Spring sow seeds directly after final frost
- Transplant milkweed plants in early spring or fall
Purple Milkweed Growing Tips
- Easiest to sow outside directly in fall (spring also works with cold stratification)
- This species is supposedly adaptable to a wide range of growing conditions, but this seems unlikely considering this milkweed is a rare find in the wild, let alone in nurseries.
- Since Asclepias purpurascens does not have a long tap root to store excess nutrients, I question reports of drought tolerance.
- Ours is planted in well-drained soil but it’s not overly dry. We mixed in composted manure before planting our purple milkweed last fall.
- Our plants will receive morning/early afternoon sun, but get a shady reprieve from the sizzling afternoon sun.
- Segregate purple from aggressive spreaders like common milkweed so your plants aren’t overcome by ravenous rhizomes.
- Protect your plants! Since these seem more difficult to establish consider putting up a fence to keep away small critters. Rabbit fencing recommended
- Cut- At mid season after the blooms have faded, cut some common stems back by about a third. This promotes fresh plant growth and could get you an extra generation of monarchs on the fresh new leaves. Leave some plants uncut if you want to harvest milkweed seeds in fall.
- Cut II- If you don’t want additional seedlings next spring, simply cut off the seed pods before they pop open or bind them shut with twist ties, rubber bands, or organza bags if you want to collect purple milkweed seeds
Purple milkweed also attracts azures, bumble bees, eastern black swallowtails, eastern tiger swallowtails, great spangled fritillaries, hairstreaks, painted lady butterflies, skippers, sulphurs, and more… (If you know of others, please comment below.)
Buy Asclepias Purpurascens Seeds and Plants
Always purchase seeds and plants by botanical (scientific) name. Asclepias purpurascens’s common name, purple milkweed, is also a common name for a western milkweed variety:
1. Purchase Purple Milkweed from Joyful Butterfly