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How to Grow Milkweed: A Must-Have Plant for Monarch Butterflies

Photo Credit
Lmmahood/Getty Images
Botanical Name
Asclepias spp.
Plant Type
Flowers
Sun Exposure
Full Sun
Soil pH
Slightly Acidic to Neutral
Bloom Time
Spring
Summer
Flower Color
Orange
Pink
Purple
White
Hardiness Zone
3
4
5
6
7
8
9
Special Features
Attracts Butterflies

Planting, Growing, and Caring for Milkweed

Written By: Catherine Boeckmann Executive Digital Editor and Master Gardener

Want to turn your backyard into a butterfly buffet? Milkweed is the VIP host plant that monarch butterflies can’t live without! With its pretty blooms and vital role in the monarch life cycle, this low-maintenance native wildflower deserves a place in every pollinator garden. In this guide, we’ll show you how to grow milkweed—from picking the perfect species to sowing seeds and caring for your plants all season long. Bonus? Bees love it too, so you’ll be the buzz of the block.

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.

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The nectar in all milkweed flowers provides valuable food for butterflies, bees, and other pollinators. Butterflies need not only nectar but also food at the caterpillar stage. The leaves of milkweed plants are the only food monarch caterpillars can eat. Monarch butterflies also need the milkweed plant to lay their eggs on.

Milkweed plant
Self-sowing milkweed before flowering! Credit: Catherine Boeckmann

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Planting

When to Plant 

  • Milkweed can be grown from seed or transplants.
  • Start seeds indoors about 4 to 8 weeks before your last frost date in the spring.
  • Alternatively, sow seeds directly into 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 before planting.
  • 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
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 has very showy orange flowers. 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, 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

  1. Cut fresh green stems (1/3 inch diameter) from young milkweed plants.
  2. Recut the stems underwater and coat the bottom of the stems with rooting hormone.
  3. Place the stems in moist sand, vermiculite, or potting soil.
  4. The stem cuttings will root in 6-10 weeks and will be ready to be transplanted outdoors. 

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Pests/Diseases

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!). 

  • Aphids
  • Milkweed leaf beetle
  • Milkweed tussock moth
  • Red and black milkweed bugs

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.
  • Milkweed is the state wildflower of Illinois.
Milkweed seed pods
Milkweed seed pods

Flowers
About The Author
Catherine Boeckmann

Catherine Boeckmann

Executive Digital Editor and Master Gardener

Catherine Boeckmann is the Executive Digital Editor of Almanac.com, the website companion of The Old Farmer's Almanac. She covers gardening, plants, pest control, soil composition, seasonal and moon c...
Read More from Catherine Boeckmann

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Comments

<a title="View user profile." href="/author/editors">The Editors</a> Wed, 01/26/2022 - 14:54

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.

 <span>Cindy</span> Wed, 05/25/2022 - 01:22
I bought my seeds from eBay seed sellers.