Asclepias verticillata.
Whorled Milkweed is a perennial wildflower native to many regions of the United States.
The upright, sparingly branched plant grows to around 18 to 24 inches in height and produces clusters of greenish-white flowers from late spring through early fall.
Attracts numerous butterflies and pollinators, particularly the monarch butterfly whose larvae feed exclusively on milkweed. Deer and rabbits avoid.
Typically blooms in its second year.
Whorled Milkweed
Growth Chart
Hardiness Zones: 3 to 11 Light Requirement: Full to partial sun Soil Type: Dry, sandy, rocky, clay Sow Depth: 1/8 inch Plant Spacing: 12 to 36 inches Germination Note: Cold stratification required Stratification Time: 30 days Bloom Time: May through September Growing Tips
Direct sow just beneath the soil's surface in late fall. Germination will occur after the last spring frost. For spring planting, mix the seeds with moist sand and refrigerate for 30 days (cold stratification) before direct sowing.
A Note on Cold Stratification
These seeds require cold, moist stratification. To naturally stratify the seeds, plant outdoors late fall on a weed-free site and allow seeds to overwinter.
To artificially stratify the seeds, place the seeds and a moist medium (such as a damp paper towel, coffee filter, sand, or vermiculite) in a labeled, sealed plastic bag and store in a refrigerator (33-40°F) for the amount of time noted on the growth chart before sowing.