Milkweed is a critically important plant for the monarch butterfly, which is threatened with extinction. The monarch caterpillar uses milkweed as its primary food source, and its powerful flowers provide nectar for countless butterflies, bees and insects.
If you stop and observe a milkweed plant in flower for even a short time, you will likely see a frenzy of insect activity, which instantly illustrates how important these plants are to nature.
Interested in providing a home for the monarch butterfly and beneficial insects in your garden? Milkweed is the answer!
One way is to preserve any existing patches of milkweed where you live. Instead of mowing the patch down, leave it up as a wildflower patch throughout the summer and autumn.
Milkweed can be cut back after it has gone to seed and the fluffy white seeds have dispersed, usually around mid-October. If the seed pods haven’t released their seeds by this time, you can open the pods and help disperse them yourself.
Don’t pull milkweed from your garden. Embrace its informal growing habit, and allow it to grow freely among your flowers. It will fit right in.
Planting native milkweed by seed or transplants is another great way to support the monarch and other beneficial insects. If sowing seeds, the ideal time to plant is autumn as the seeds require cold stratification. In other words, the seeds need prolonged exposure to cold winter temperatures to break their natural dormancy cycle, which stimulates germination in the spring.
For transplants, wait until early spring after the danger of frost has passed to plant. Autumn planting may not give them adequate time to get established before winter.
You can sow seeds in spring, but they will need to be cold-treated for a high germination rate. To do this, place the seeds in moist paper towels in a plastic bag or container in a refrigerator with the temperature at 40º F for a minimum of three weeks to three months.
It is important to purchase locally sourced seeds or plants. Place-specific genetic variations can develop by region, so sourcing your plants near where you live will have the most beneficial result.
When you think of milkweed, common milkweed is the plant that most likely comes to mind. This species grows two to three feet tall with showy and fragrant dusty pink to mauve flowers. It grows well in full sun with dry to medium dry soil moisture.
With striking orange flowers, butterfly milkweed is a showstopper in the garden. While slow to grow, the vibrant flowers on this perennial make it worth the wait. Growing one to 2.5 feet tall, it also prefers full sun and dry to medium dry conditions.
Swamp milkweed has very place-based genetics, so it is especially important to source this species locally. It has dusty pink flowers and grows taller than the previous species at three to four feet tall. As indicated by the name, this milkweed prefers soils that are medium to wet in moisture and full sun.
Another native, whorled milkweed has delicate white flowers and can reach heights of one to 2.5 feet. You can plant this in full sun or part shade. It grows best in dry to medium dry soil conditions.
Interested in learning about how to plant milkweed by plant or seed? Check out the Monarch Joint Venture (https://go.uvm.edu/milkweed) for detailed instructions.
Considering its significance to the monarch and its magnet-like attractiveness to beneficial insects, milkweed is one of the most satisfying plants to grow in the garden. Whether you are tending an existing patch or planting your own, give this incredible plant a try. Nature will thank you.
by Bonnie Kirn Donahue, Extension Master Gardener, UVM
Header photo: Reaching heights of three to four feet, swamp milkweed is one of the best milkweeds to plant in a butterfly garden as it feeds both monarch caterpillars and butterflies.