Types of milkweed to support monarch butterflies
It’s best to grow a milkweed that is native to your area so monarch butterflies that visit find the habitat to which they are accustomed. You can grow other species, but the natives are suited to your region. Most milkweeds grow best in full sun, but they will tolerate some shade. With the exception of swamp milkweed, which prefers moist, rich soil, milkweed species will thrive in poor, dry soils and disturbed areas, fields, and ditches. Also keep in mind that milkweed plants have some toxicity — so keep them out of places where livestock may graze and don’t let pets or children chew on them.
Milkweed is a host plant for monarch caterpillars
Though adult monarch butterflies sip nectar from many flowers, monarch caterpillars feed exclusively on milkweed plants, specifically those in the genus Asclepias. Monarch butterflies lay their eggs on milkweed plants so their larvae, or caterpillars, have an instant food source once the eggs hatch. Chemicals in the milkweed are ingested by the caterpillars which are toxic to other animals, helping protect them from predators. Caterpillars and adult butterflies are also brightly colored, a natural warning that this insect is toxic.
Where to buy native milkweed seeds & plants
The Xerces Society can help you find a seed source in your area. Visit their Milkweed Seed Finder here for more information.
How to keep milkweed from taking over your garden
Many people consider milkweed a weed, but go ahead and plant those pretty “weeds.” The monarchs will thank you. However, if you are worried about these plants spreading too much or your neighbors complain, there are a few things you can do:
Contain milkweed rhizomes
Since milkweeds multiply through underground rhizomes and by seed, keep a small milkweed clump contained by sinking 12- to 18-inch plastic or metal edging into the ground around the plants. Or periodically spade into the ground around the base of the plants and remove any wandering rhizomes from the soil.
Remove seed pods
You'll also want to cut green seed pods off so they can’t produce seed. It won’t bother the monarchs — they feed on leaves and stems as caterpillars and nectar as adults, so they won’t even notice the pods are gone!
Find the right type of milkweed to grow in your region
Here is a list of 8 native milkweeds and regions they are found across the contiguous United States and Canada. Find your region on this map, then look for one or more that you can grow in your area. For more regional information about milkweed, visit the Xerces Society website.