Growing Common Milkweed for Monarchs (and more!)

Common milkweed (Asclepia syriaca) is a native perennial to Wisconsin and is an essential plant for monarch butterfly survival. Monarch adults will only lay their eggs on milkweed plants, and their caterpillars will only consume milkweed. Although adult monarchs do not prefer to drink the nectar of common milkweed, the flowers are visited by many native, beneficial pollinators such as moths, solitary wasps, and dozens of species of bees!

Check out the notes and video below for more information about gardening with milkweed.

Notes about this plant:

• Flowers in early-mid summer

• Full sun to part shade

• Start seeds indoors* two months before final frost date, OR sow directly in the soil in spring before final frost, OR scatter seeds in fall.

• Note: common milkweed can spread quickly through seeds and rhizomes, but pull out easily from the ground as young shoots. To control the spread, remove the seedpods in fall, and weed out unwanted new shoots in spring.

The seeds you are using were collected and cleaned by volunteers and staff with Southern Wisconsin Bird Alliance at Goose Pond Sanctuary.

*Starting your seeds indoors:

Milkweeds, like many native plants, require a time of cold stratification—or going through a cold period to trigger the seed’s germination hormones. This is an easy, inexpensive process that will help increase the number of seeds that sprout and flourish in your garden, over directly sowing the seeds into the ground.

6 Tips for cold stratification and germination:

1. Label a zip-lock bag with the species and date.

2. Add a handful of moist (not soggy) sand or vermiculite. Seed-starting or potting soil can work, usually but not as well.

3. Add the milkweed seeds and mix.

4. Close bag and place in refrigerator for 4-6 weeks. Leave the bag closed except for when you check the seeds weekly for mold or sprouting.

5. After the last chance for frost has passed (around May 20th for Madison area), sow the seeds into your garden bed, approx. 1 inch deep.

6. If your seeds begin to sprout in the fridge, gently transplant them into a seed-starting mix and place in a sunny place indoors until the last chance for frost has passed.

Starting your seeds outdoors:

Milkweed seeds can be scattered in an area you want them to grow, ideally in fall so the seeds have the time to naturally cold stratify throughout the winter. Scattering in spring, summer, and winter is fine too, but animals (birds, mice, etc.) may eat the seeds before they germinate.

Want to go a step further?

Distribution of milkweed seed is free, but your voluntary donation will help support our important work and enable us to continue this important restoration work. If you are interested and able to make a donation, you can do so here — put “milkweed seed” in the comments.

Header photo by Emily Meier.