Follow our instructions for starting milkweed from seed, including Common Milkweed (Asclepias syriaca), Swamp Milkweed (Asclepias incarnata), and Whorled Milkweed (Asclepias verticillata). We have found these techniques best for good growing results.
Without prolonged exposure to cold temperatures, your milkweed seed is unlikely to sprout.
Getting Started: Understanding Milkweed Seed & Germination
Milkweed seeds require cold stratification.
In most areas, when you plant seeds outside in fall, seeds can go through the cold stratification process naturally. If you are planting seed outside, we suggest seeding in late fall so that Milkweed seeds can lay on the ground through winter. This will give your Milkweed seed a long winter of dormancy. Once the sun comes out and the ground is warm in the spring, the seeds will germinate on their own.
In warm zones without winter frost, or if you are starting your seeds in spring, you can cold-stratify seeds in your refridgerator!
3. Water the area thoroughly and let it saturate the soil.
If you still need to collect milkweed seeds from your garden or local milkweed patch, check out this article to how to harvest milkweed seeds.
10 Simple Steps for Fall Planting Milkweed
4. Put on garden gloves and stick your index finger in the dirt up to your first knuckle.
Fall planting is a great way to get your perennial milkweed varieties started, since the seeds will need cold stratification…and Father Winter takes care of this naturally! Consider planting milkweed varieties that are native to your region for best results.
Warm weather milkweeds, which are annuals for most of us, do not require this cold treatment. These varieties include tropical milkweed, swan milkweed, goose plant, and giant milkweed.
Your milkweed purchase is the first step in creating habitat for the monarch butterfly. It is important to sow the seed correctly to give the seeds the best opportunity to germinate and grow. Make sure that you are able to achieve a good seed to soil/mulch contact before sowing the seed. The seed must contact its growth medium in order to anchor in and begin the germination process. Seeding can occur between October and June, but should not be completed during the summer months. Once the seed is broadcast, work the seed into the soil to a depth of 1/8th inch. This can be accomplished by flipping over a garden rake and lightly moving the seed and the soil/mulch. Straw may be added but is not necessary. Often time, straw introduces weed seed that competes with the milkweed plants.
Milkweed are perennial plants and may take multiple seasons to germinate and grow. Most species need to go through a cold stratification process in order to germinate. This means that if you sow the seed in the spring after the freeze/thaw process the seeds will most likely lay dormant until they can be stratified the following winter. Keep in mind that just because you can’t see the milkweed doesn’t mean it’s not growing. Perennial plants will put down roots for stability prior to emerging above ground. It is these deep root systems that will enable your milkweed plants to be a home to Monarchs for future generations.