Asclepias incarnata, commonly called swamp milkweed, is an erect, clump-forming native plant which is commonly found in swamps, river bottomlands and wet meadows. It typically grows 3-4' tall (less frequently to 5') on branching stems. Small, fragrant, pink to mauve flowers (1/4" wide), each with five reflexed petals and an elevated central crown, appear in tight clusters (umbels) at the stem ends in summer. Flowers are uncommonly white. Narrow, lance-shaped, taper-pointed leaves are 3-6" long. Stems exude a toxic milky sap when cut. Flowers are followed by attractive seed pods (to 4" long) which split open when ripe releasing silky-haired seeds easily carried by the wind. Flowers are very attractive to butterflies as a nectar source. In addition, swamp milkweed is an important food source for the larval stage of Monarch butterflies. Sunny borders, stream/pond banks, butterfly gardens. A good plant for low spots or other moist areas in the landscape. Easily grown in medium to wet soils in full sun. Surprisingly tolerant of average well-drained soils in cultivation even though the species is native to swamps and wet meadows. Hardy in zones 3-6.
Growing Instructions for the Swamp Milkweed
The seeds have a period of dormancy. They can be planted outdoors in the fall or winter for spring germination or they can be cold stratified to simulate winter conditions and to break their dormancy at any time of the year. 1. Put the seeds in a ziplock bag. 3. Put the bag in the refrigerator and leave it there for 4 weeks. 2. Prepare a mixture of half potting soil and half sand, perlite or vermiculite. Water the mixture so that it is moist but not wet. 3. Put the seeds on the soil. 4. Cover the seeds with a thin layer of soil. 5. Water the seeds. 6. Place the pots in an area with warm temperatures in full sun or part shade 7. When the seedlings are a few inches tall, they can be transplanted.