Whorled milkweed, (Asclepius verticillata). Photo by Steve Glass.
More Milkweed Plants
If you, like me, want more milkweed plants in your butterfly or pollinator garden next summer, now is the time to get started. You can sow seeds outdoors this fall either in pots, in flats, or directly in the ground. After a period of cold stratification, seeds will germinate next spring and blooming plants will be ready in 2-3 years.
Species of milkweed, and many other native plants that attract beneficial insects, germinate easily from seed after period of winter cold outdoors. Spring seedlings can be transplanted to larger containers the first or second growing season or when the second set of true leaves appears. They will usually bloom the second or third growing season.
The three species of milkweed most commonly cultivated in Wisconsin—common, marsh, and butterfly milkweed—can all be grown from seed by this method.
Seeds of common milkweed (Asclepias syriaca) ready to be sown. Photo by Steve Glass.
Strive for Diversity
Each year I add a few native plants to my prairie garden, using this method, in hopes of increasing the number and kind of species that are attractive to native bees, butterflies, and other beneficial insects. I look for plants that provide habitat, or serve as pollen, nectar, or food sources for as many of our native insects as possible.
“To make a prairie it takes a clover and one bee
One clover and a bee
And reverie
The reverie alone will do
If bees are few”
—Emily Dickinson
By growing from seed you can save some money over the cost of mature plants. In addition—if seeds are obtained from known and trusted sources—you can be assured that the seed is from a local source and appropriate for your region. But more importantly, from an ecological perspective, by growing from seed (rather than purchasing identical cloned plants) you can boost the genetic diversity of local plant populations.
To obtain seeds, do not collect from nature preserves or other wild places without permission. In fact, check first with local conservation organizations or native plant societies as they may make milkweed seeds available to you either free or at a nominal cost as part of their education programs.
Butterflies and Milkweed
My experience last summer tells me my garden needs more—lots more—milkweed plants; perhaps several dozen more.
Although this past summer I reared and released 22 monarch butterflies from eggs and caterpillars found on more than two dozen milkweed plants in my prairie garden, there could have been more butterflies headed to Mexico late last summer if my gardens grew more milkweed.
Milkweeds are essential because monarch butterflies (Danaus plexipus) lay their eggs only on milkweed leaves and the caterpillars eat only milkweed leaves. This is an obligatory relationship: no milkweeds means no monarchs.
Simply put, there were not nearly enough milkweed plants in my gardens to host and provide food for as many of the monarch butterfly caterpillars that I had hoped would temporarily call my Monarch Way Station home.
My resolution is that next summer there will be more milkweeds in the garden so I am starting production now. This fall I will be sowing seeds of common, marsh, and butterfly milkweed in flats and letting them overwinter outdoors.
I’ll also plant several varieties of blazing stars and gay feathers (liatris), asters, and goldenrods to provide nectar for the adult butterflies.
Getting Started
Milkweed seeds sown 3 to a cell in a seedling tray.
It’s easy, fun, and satisfying to grow plants from seed. Follow these steps:
- Use individual pots or a seedling tray with individual planting cells at least 3” deep and fill with a good quality commercial grade potting soil.
- Sow 2-3 seeds per pot or seedling tray cell and cover with a layer of soil about as thick as the seeds (about 1/8” to ¼”).
- Cover the soil surface with a thin layer of coarse sand to prevent the seeds from washing away in a rain.
- Label each pot or seedling tray with the species name and date planted.
- Water thoroughly and cover with hardware cloth or other wire mesh to prevent rodents from getting at the seeds.
- Keep moist until the soil freezes
- Keep outside or in an un-heated garage where the pots/seedling flats will stay frozen until spring.
- Resume watering in the spring and look for tiny seedlings to appear.
- Thin the seedlings to one per cell.
- Transplant individual plants to larger containers after the second set of true leaves appears.
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