The perfect time to sow native milkweed outdoors is right when Mother Nature does it, in the fall! Exposure to cold temperatures and moist conditions during winter will stimulate germination. Spring planting is also possible but artificial stratification of the seed is recommended to enhance germination. (Click here to read how to plant milkweed in the spring.)
Choose your Area
Native milkweeds need full sun to grow so make sure the area you choose has at least least 6-8 hours of sun per day.
Prepare the Soil
Like all wildflowers, milkweed should be planted on bare soil. Remove existing plants and weeds and then rake the soil up to remove large rocks and other debris. Make sure there is no existing growth in the area before planting, so the milkweed seeds won’t need to fight underneath the surface to establish their roots.
Sow the Seeds
Be sure to wait until the first killing frost to sow the seeds. Space the seeds out one by one about 10-12 inches apart. If you have a large area and a quantity of seeds you can simply throw them out by the handful. If you do scatter them loosely by hand, come spring when the seeds start to germinate you may want to thin them out if they are extremely close together.
Do not cover the seeds! Simply press them against the soil with your hand or the sole of your shoe. If you’re seeding a large area you could also use a seed roller. Milkweed seeds require light to germinate, so if you cover them with soil, they won’t germinate come spring.
Once you’ve pressed the seeds into the soil, give the area a good watering to set the seeds. Because you’re planting in the fall, you won’t need to water after this until early spring when the seeds start to germinate.
Now walk away and forget about them and let Mother Nature do her magic. As winter progresses, they’ll naturally be exposed to the eight to ten weeks of cold temperatures required for them to germinate when spring arrives.