Milkweed (Asclepias) is a native wildflower we should all grow for the butterflies—specifically Monarchs! The Old Farmer’s ÃÛÌÒÁµÈË will help you choose your milkweed plants, explain when and how to plant, and instruct you on after-season care.
About Milkweed
Several popular species are suited for cultivation in the garden. Common milkweed (Asclepias syriaca) is the best-known of the over 100 perennial milkweeds 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 monarch caterpillars can eat. Plus, monarch butterflies also need the milkweed plant to lay their eggs on.
Self-sowing milkweed before flowering! Credit: Catherine Boeckmann
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.
Where to Plant
Milkweed plants require full sun.
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. They can grow quite tall and need lots of space for their deep root systems to spread. They do NOT like to be transplanted.
Consider planting low-growing perennials
Plant low-growing perennials in front of the milkweed.
How to Plant
If you plant from seed, scatter seeds on top of the soil and cover with about ¼ inch of additional soil. Seeds will germinate in 7 to 10 days. Thin seedlings to 2 inches apart.
If you buy small plants, choose healthy specimens with well-developed root systems. Gently loosen the roots a bit before planting.
Plant to plant transplants in blocks rather than long rows. Space milkweed 18 to 24 inches apart.
Dig a hole that’s two times as deep and wide as the rootball of your plant. There is no need to amend healthy soil or amend it with a little compost.
Plant with the top of the root ball even with the soil line, and fill the rest of the hole with extra soil and firm up the area.
Water after planting to compress the soil and keep the soil moist until plants are established.
Growing
How to Grow Milkweed
Do not worry if the plants take time to get going. They stay dormant longer than most plants but should start leafing out in late spring or early summer. Avoid watering during dormancy. If they don’t flower in the first season, their leaves still provide a food source for Monarch babies.
Common Milkweed and Butterfly Weed need little water and thrive in a drier environment. Swamp and Tropical Milkweed need to be watered but not overwatered
Water plants if the soil is dry, but avoid overwatering (especially during early dormancy).
The good news is that milkweed is otherwise left alone. Do NOT fertilize, spray, or prune.
Butterfly weed, Asclepias tuberosa. Photo by NNehring/Getty Images.
Types
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.
Harvesting
Once established, milkweed does NOT like to be transplanted or divided. If possible, leave milkweed alone.
If you are bothered by the plants’ more scraggly looks or half-eaten leaves late in the season, remember to plant them at the back of your garden (or in their own space) and low-growing perennials in the front to hide the milkweed stems.
As with many native plants, milkweed will self-seed which is a free and natural way of spreading Monarch food. If you do NOT want milkweed spreading in your garden bed OR you’d like to plant some milkweed in a different location, you can remove the seedpods (before they burst open) and scatter the seeds elsewhere.
You can also propagate milkweed from cuttings and give the plant to friends!
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.
Gardening Products
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.
Milkweed isn’t severely affected by pests, diseases, or problems. You are most likely to see aphids enjoying the nectar! Just squirt with a water hose (but be careful to check for Monarch eggs!).
Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s ÃÛÌÒÁµÈË found each other. She leads digital content for the ÃÛÌÒÁµÈË website, and is also a certified master gardener in the state of Indiana. Read More from Catherine Boeckmann
You can find milkweed seeds on a number of seed-selling websites, or you may be able to find them at your local nursery. You should also be able to find young plants at nurseries.
We wouldn’t recommend taking milkweed from the wild, as it should be left in its natural habitat! It also may be illegal in some places. If you happen to have a friend with milkweed on their property, perhaps they could give you some seeds at the end of the season.
