Purple Milkweed Seeds for your Butterflies
Purple Milkweed (Asclepias Purpurascens) is a rare, herbaceous perennial that will die back in the fall to return in the spring. It is hardy in USDA zones 3a-9b and could grow from 2-3 feet tall (sometimes even taller than that) and about 1-3 feet wide.
It is unique in that it posses the most beautiful purple flowers of all of the milkweeds. Blooms appear in summer (June-July in our zone 7) and can last for about one month. If no seed pods are set, they will usually re-bloom. There is some patience required as it might take 2 to 3 years for young plants to bloom.
Their fragrance attracts many pollinators and different kinds of butterflies such as: Eastern Black Swallowtails, Eastern Tiger Swallowtails, Great Spangled Fritillaries, Hairstreaks, Painted Lady Butterflies, Skippers, Sulphurs, Red Admirals, and more.
This plant is also a food source for the Monarch caterpillars. The leaves are about 6-8 inches long with the mid-vein tinted the same rich purple color as the flower.
Purple Milkweed Growing Conditions
Asclepias Purpurascens is native to most of the Eastern, Southern and Midwestern parts of the United States and the region around Ontario, Canada (very similar to the range of Common Milkweed). Not only is it very rarely found growing wild, but it is also very hard to find for purchase in nurseries. It is declared an endangered species in the state of Wisconsin and threatened in Massachusetts.
This plant likes full sun to partial shade (prefers morning sun and afternoon shade). It does not have the long tap root or an underground rhizome (typical of milkweeds) so it does not tolerate drought. Purple Milkweed should be planted in well-drained soil, enriched with light amount of composted cow manure (high nutrient requirement), and might possibly favor calcium rich sites.
How to Grow Purple Milkweed Seeds
From our experience we’ve learned that these seeds need a period of 1 month of cold stratification. These can then be started indoors during spring in potting soil at a depth of about 1/8 inch. They germinate readily at room temperature in 1-2 weeks after cold stratification. We see 40-60% germination each year with different batches of seed and have found no increase with longer stratification. If you have a technique for increased germination rates please let us know so we can share it here!
Another option would be to sow the seeds directly outside in the fall or winter.
Buy Asclepias Purpurascens Milkweed Seeds and Plants
Due to its rarity, you may want to get your hands on these specimens whenever the opportunity arises. This native plant needs some help getting re-established! Purple milkweed is not invasive, has pollinator-attracting blooms, beautiful dark purple flowers, and is easy to transplant.