Grow Whorled Milkweed Seeds (Asclepias verticillata) for Monarchs and Other Butterflies
Asclepias verticillata, commonly known as whorled milkweed or horsetail milkweed, is one of the milkweeds used as a host plant by Monarch caterpillars for food. Female Monarchs lay their eggs on this milkweed so the caterpillars can eat the leaves for growth before becoming a chrysalis.
The flowers of this plant are loved by many adult butterflies as a nectar source so this makes it a great double-duty plant performing as both a nectar plant and a host plant in butterfly gardens.
Asclepias verticillata Characteristics
Whorled milkweed is native to the US from the Rocky Mountains through the East and is usually found along roadsides, in prairies, on the edge of woodlands and other dry, sunny areas.
It is a herbaceous perennial that is hardy in zones 3-9 (some sources say 4-10). It is shorter than some other milkweeds growing about 2 feet tall. This milkweed prefers full sun but will tolerate partial shade and is drought tolerant.
It will do well in medium moist gardens but can become somewhat invasive (not as aggressive as Common Milkweed) as it spreads by underground rhizomes. When given some room it will make beautiful colonies that are in bloom from mid-summer through fall.
The flowers are white with hints of green and are fragrant. The leaves are thin and in a whorled pattern, usually on a single stem. Asclepias verticillata generally stays vibrant later in the season than many other milkweeds that bloom earlier so it is an important food source for fall-migration Monarchs.
Starting Whorled Milkweed Seeds
Propagation can take place through seed or rhizome cuttings.To start from seed they must first be cold stratified (unless fall or winter sown). After 30 days of cold stratification, they should be planted about 1/4″ deep, kept moist around room temperature, and should germinate in 10-15 days. These seeds can also be fall or winter sown. Space or thin plants to about 1-2 feet apart.
Whorled milkweed seeds can be collected from mature plants just as the long smooth pods are dry and beginning to split. If you prefer to prevent reseeding, just remove the seed pods before they open.
Why Buy Asclepias verticillata?
If you are looking for a shorter, colonizing milkweed that blooms later in the summer than most milkweeds with fragrant white flowers, then this is a great choice. As a native, drought-tolerant, and robust milkweed, it should bring interest and butterflies to your larger gardening areas.