Butterflies love native plants, and some rely on native plants, sometimes one or two species, in order to complete their life cycle. Monarch butterflies arrive to southern Ontario in late summer, just as the Milkweeds are blooming. The adults feed on other plants too, throughout the fall, but in their caterpillar stage they eat milkweed leaves exclusively.

Monarch butterfly populations are shrinking and at risk of extinction. In Canada, they are now listed as an Endangered Species. One contributing factor may be the loss of high quality native meadow habitats which provide diverse, late blooming wildflowers for adults to nectar from, as well as milkweed host plants.

Situated just north of Long Point Provincial Park, a designated Monarch Reserve, St. Williams Nursery & Ecology Centre (SWNEC) is increasingly involved in restoring Monarch habitat in the region, and across the province. SWNEC presently grows six different species of milkweed, so that nearly every habitat type can become a nursery for Monarch caterpillars:

Some, like the Whorled  and Sullivant’s Milkweed, are specialists and will only thrive in very specific conditions. Be sure you match the appropriate species to your project’s site conditions.

All of our native plants are ethically sourced from wild remnant populations in Ontario, and accessioned according to biogeographic region. Each and every milkweed seedling is grown from local seed, collected by hand, and with great excitement!

Carried by their parachutes in the wind Milkweed seeds disperse in the fall and colonize newly disturbed ground. Just before the seed pods ripen, our seed collectors harvest whole pods from fields and from crop rows at the SWNEC farm. The pods are dried on tarps, and the fluff inside is processed to separate the parachute or pappus from the live seed.

This can be done several different ways. For a medium sized batch, you can use a shop-vac and screen to clean milkweed seeds. The vacuum separates the light material from the heavy seed. Because we harvest large amounts of seed, we use a much larger machine called a de-bearder, which is basically a large dry blender, turned on its side, which gently, but firmly, knocks the seed loose from the pappus.

Some seeds are destined for direct-sown habitat creation projects that SWNEC is involve with. Some seed is destined for specialty packs to be given as wedding favors. Some seeds are destined for the greenhouse where we will grow them into seedling plugs and potted plants for wetland restorations, home gardens, and public parks.

Some years, the Monarchs lay thousands of eggs on milkweed seedlings inside of our open-roof greenhouse. They seem to be attracted to the dense concentration of young, tender milkweed shoots, combined with a dense collection of flowering.


Blog contribution by Stefan Weber – SWNEC Ecologist

Growing Milkweed Seeds For Monarch Conservation In Ontario