Milkweed is a native wildflower beloved by monarch butterflies. There are a number of popular species suited for cultivation in the garden. Here’s how to plant, grow, and care for milkweed in your garden—and support butterflies!
Common milkweed (Asclepias syriaca) is the best known species of the over 100 perennial milkweed species native to North America. Milkweed plants support 12 species of butterflies and moths, including the Monarch butterfly.
The nectar in all milkweed flowers provides valuable food for butterflies, bees, and other pollinators. Butterflies don’t only need nectar, but also need food at the caterpillar stage. The leaves of milkweed plants are the only food that monarch caterpillars can eat. And monarch butterflies also need the milkweed plant to lay their eggs on.
Start seeds indoors about 4 to 8 weeks before your last frost date in the spring.
Alternatively, sow seeds directly into the garden soil in the fall or in early spring.
Choosing and Preparing a Planting Site
Milkweed plants require full sun and a lot of space.
Milkweed does best in well-draining soil, although some species, like swamp milkweed, prefer to grow in soil with higher moisture levels.
Plant in the back of flower beds or create a bed for just milkweed.
How to Plant Milkweed
Scatter seeds on top of the soil and cover with about ¼ inch of additional soil.
Seeds will germinate in 7-10 days.
Thin seedlings to 2 inches apart.
Transplant seedlings when 3-6 inches tall.
Plant transplants in blocks rather than long rows. Plant milkweed 18-24 inches apart.
Water after planting and keep soil moist until plants are established.
Add mulch around the plants to keep the soil moist and discourage weeds.
How to Grow Milkweed
Water plants if soil is dry, but avoid overwatering.
Plants generally do not need supplemental fertilization.
Avoid using insecticides/herbicides in areas around milkweed.
Plants may not bloom the first year, but leaves will still provide a food source for butterfly caterpillars.
Common milkweed (Asclepias syriaca) is a hardy perennial that will thrive almost anywhere in the United States, especially east of the Rockies and into Canada. It needs sun, reaches 2 to 6 feet tall with wide, gray-green, velvety leaves, and is an aggressive grower. Don’t plant this in your flowerbed, or it will take over. It has a wide-spreading root system and needs an area all its own, where it can really stretch out. It has pale purple-pink flowers that are very fragrant and attract many pollinators in addition to Monarch butterflies.
Butterfly weed(A. tuberosa) is less aggressive than the common milkweed, growing only 1 to 2-1/2 feet tall. It is commonly grown in gardens, adapts well to moist or dry soil, and its orange flowers are very showy. It likes full sun and is hardy in Zones 3 to 9.
Swamp milkweed (A. incarnata) has thinner leaves and more colorful flowers than common milkweed. It is better-behaved than common milkweed, forming clumps rather than spreading out. It grows 2 to 4 feet tall, has deep rose-pink flowers, and is shade tolerant. It will grow in wet soil near lakesides or damp marshlands, but also grows well in average garden soil and is hardy in Zones 3-9.
Showy milkweed (A. speciosa) is native from west of the Mississippi into California and north to Canada. It has pastel pink flowers on 2- to 4-foot tall plants. It is drought tolerant, making it a good plant for arid plains and prairie-lands, though it grows well in moist garden soils as well. It needs full sun and is hardy in Zones 3-9.
Propagating Milkweed from Cuttings
Cut fresh green stems (1/3 inch diameter) from young milkweed plants.
Recut the stems underwater and coat the bottom of the stems with rooting hormone.
Place the stems in moist sand, vermiculite, or potting soil.
The stem cuttings will root in 6-10 weeks and will be ready to be transplanted outdoors.
Wit and Wisdom
The genus name, Asclepias, commemorates Asklepios, the Greek god of medicine.
Native Americans taught early European settlers how to cook milkweed so that it could be safely eaten.
The milky white sap was applied topically to remove warts, and the roots were chewed to cure dysentery.
Infusions of the roots and leaves were taken to suppress coughs and used to treat typhus fever and asthma.
The stems’ tough, stringy fibers were twisted into strong twine and rope, or woven into coarse fabric.
Inside milkweed’s seed pods is fluffy white floss attached to brown seeds. The floss was used to stuff pillows, mattresses, and quilts, and was carried as tinder to start fires.
During World War II, the regular material used to stuff life jackets was in short supply, so milkweed floss was used as a substitute—it is about six times more buoyant than cork.