How to harvest and plant milkweed seeds

By: Jennifer Howell

Learn how to collect, harvest, and plant common milkweed seeds to attract monarch butterflies to your garden.

how-to-grow-milkweed-pv: Monarch catapillars like this one rely on common milkweed as their host plant each year.

Support monarch butterflies with milkweed

Want to help stop the decline of monarch butterfly populations and bring more of these fluttering beauties back into your garden? Plant milkweed — it’s the sole food source for monarch caterpillars and is attractive to many pollinators for its nectar-rich flowers.

how-to-grow-milkweed-plugs-short: Planting plugs of started milkweed is one way to grow milkweed in your garden.

Growing milkweed

You can plant milkweed starter plants purchased at specialty nurseries. Any species in the milkweed family will do, but the easiest to grow is the common milkweed, Asclepias syriaca. Plant them in full sun in groups of three to six spaced 6 to 24 inches apart scattered around your garden. Smaller groupings are less prone than mass plantings to insect or parasite infestations or predators.

It’s also easy to collect milkweed seed (be sure to ask property owners first) and start it yourself. See the gallery at the bottom of the article for our tips on how to collect seeds.

milkweed-planting-seeds: Simply sprinkle milkweed seeds on well-tilled soil and pat them down, add a topdressing of soil and water them in. Fall-sown seed will be naturally stratified outside.

Planting milkweed seeds

Milkweed seeds need to be stratified to help them germinate. Stratification is when a seed is moistened, chilled or frozen and thawed, breaking down germination inhibitors on the seed coat, such as waxes, hormones, oils or heavy coats. Milkweed seed planted in fall is naturally stratified. Spring-planted seeds need to be chilled in the refrigerator, which replicates the natural process of snow and cold breaking down the seed casing.

Learn more about prechilling seeds before planting

Fall seed planting

Plant seed in fall in a sunny location. Simply sprinkle seeds on well-tilled soil and pat them down, add a topdressing of soil, and water them in. Fall-sown seed will be naturally stratified outside.

Spring seed planting

You can plant milkweed seeds in early spring as soon as the soil can be worked, but they will need to be stratified for 2 to 3 months in the refrigerator before planting in spring for better germination.

When emerging milkweeds have three to four sets of leaves, thin seedlings to 6 inches apart.

Starting seeds indoors in winter

You can also start stratified seeds indoors in late winter. Sow 2 to 3 seeds in a pot filled with seed-starting mix, cover with ¼ inch of mix, water lightly and set under lights. Germination takes 7 to 10 days. Plant seedlings outside in a sunny spot when they have 3 to 4 sets of leaves and the ground is warm.

Did you know you should sow these perennial seeds in fall?

Tips for harvesting milkweed seeds

Step 1: Harvest seed pod from milkweed plant

Pick pods as they turn brown, dry and mature. The brown dried pod in the upper left is just beginning to split open — perfect to harvest the seed.

Once the floss fluffs out like the one in the lower left, it is harder to remove from the seed. Leave this pod alone to scatter seed in the wind.

Step 3: Carefully remove the milkweed seed cluster

The seed cluster can then be removed carefully from the milkweed pod. When fully ripe and dried, the seeds will be easily separated from the floss.

Step 2: Open milkweed seed pod

When you are ready to harvest seeds, pry open the dried pods at the split seam before the fluffy floss escapes.

Step 4: Separate seeds from milkweed floss

Grip the floss end of the cluster with one hand and gently remove the seeds from the floss with the other hand, brushing them off into a bowl.

Let them dry for a week or so in a cool, dry location. Store them in an envelope at 40 degrees F or in the refrigerator to stratify until you are ready to plant in spring.