Growing milkweed is easy, but you want to start by choosing the right kind.
More than 100 milkweed species grow in North America, but only about one-fourth of them are good for supporting monarch butterflies, according to information from the U.S. Forest Service.
Some types of milkweeds, called swallow-worts, can fool monarchs into laying their eggs on them. What then happens, the caterpillars don’t get what they need from the leaves to develop into butterflies.
The three types of milkweed Monarch Watch recommends for Ohio are swamp milkweed, common milkweed and butterfly milkweed, also called butterfly weed.
As its name implies, swamp milkweed (Asclepias incarnata) is best for wetter sites, said Bob Kehres, owner of Ohio Prairie Nursery in Hiram Township, which sells milkweed and other native plants. Swamp milkweed grows about 3½ feet tall and produces white, pink or mauve flowers.
Butterfly weed (Asclepias tuberosa) is better suited to drier sites, Kehres said. It reaches only about 2 feet tall and has bold orange flowers.
Kehres said common milkweed (Asclepias syriaca) is the most adaptable, suitable for soils that ranges from a little dry to a little wet. It’s also the most fragrant of the three and the tallest, stretching to 4½ feet or more. Its flowers range from light pink to reddish-purple.
Common milkweed spreads fairly aggressively by underground rhizomes. So if you want to keep its spread in check, Kehres recommended planting common milkweed in a bottomless pot sunk in the ground.
This year, Kehres is selling his milkweed only by seed, which can be ordered at www.ohioprairienursery.com.
The educational organization Monarch Watch offers seed kits to help people start monarch way stations. The $16 kits contains seeds for milkweed and other native plants, along with a guide to creating a way station. They can be ordered at http://shop.monarchwatch.org.
Monarch Watch also sells flats of small milkweed plants, which Taylor said are easier for average gardeners to start in their yards than seeds. Information on ordering the flats, which cost $60.80, is at http://monarchwatch.org/milkweed/market.
Kehres recommended mulching the soil around milkweed plants to conserve moisture and moderate the soil temperature. The plants can be watered during dry periods, but there’s no need to fertilize them, he said.
He recommended pruning the plants late in the season, when they start to dry out.
That encourages them to send out new, tender growth to feed the caterpillars.
— Mary Beth Breckenridge