How to Grow and Care for Common Milkweed (2023)

Common milkweed (Asclepias syriaca) is a native herbaceous perennial that appeals to butterflies—especially the monarch butterfly. Asclepias is the only plant family that serves as the host plant for monarch butterfly egg laying. The monarch larvae, the hatchling caterpillars, feed exclusively on milkweed leaves. Without milkweed, there can be no monarch butterflies.

Common milkweed grows quickly to two to four feet in height. It has a narrow vertical growth habit and thick, long, oblong green leaves that grow to about eight inches.

Plant seedlings in the early spring after the danger of frost has passed and direct-sow seeds in the ground in the late fall. Once established, milkweed spreads rapidly by self-seeding if seed pods are not removed. In late spring to mid-summer, fragrant clusters of pink-purple flowers appear. Milkweed's leaves and the milk-like substance within are poisonous, except to monarch butterflies.

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Common NameMilkweed, common milkweed
Botanical NameAsclepias syriaca
FamilyApocynaceae/Asclepiadaceae
Plant TypeHerbaceous perennial
Mature Size2 to 4 ft. tall
Sun ExposureFull sun
Soil TypeAny well-drained soil; tolerates clay soil and poor, dry conditions
Soil pH4.8 to 7.2
Bloom TimeJune to August
Flower ColorPink, mauve, white
Hardiness Zones3 to 9 (USDA)
Native AreaEastern United States
ToxicityToxic to humans and animals

Common Milkweed Care

Plants in the milkweed family are the single most important source of food for the threatened monarch butterfly, and planting a patch or two in your landscape is an important contribution to the continued existence of the species.

Plant common milkweed about 18 inches apart; their rhizomatous roots will quickly fill in the space between plants. Your biggest maintenance challenge will probably be in containing them. Asclepias syriaca spreads both via seeds and rhizomes, forming colonies.

The flowers produce warty seed pods two to four inches long that split when ripe to cast many fine seeds to the wind. You might want to remove the seed pods before they open to reduce spreading. If you let the plant go to seed, they will sprout in distant corners of your yard (and beyond), thanks to the silky appendages that allow the seeds to waft on the slightest breeze. They are rather like the seeds of dandelions in this regard. Common milkweed might not be the best choice for formal perennial borders because of its tendency to get weedy and spread aggressively. It's better suited for naturalized areas like open fields and meadows and butterfly gardens.

How to Grow and Care for Common Milkweed (1)

(Video) Learn to Grow: Common milkweed

How to Grow and Care for Common Milkweed (3)

How to Grow and Care for Common Milkweed (4)

Light

Common milkweed prefers full sunlight. It grows best in an open area where there are six to eight hours of sunlight per day.

Soil

This plant prefers dry to medium average, well-drained soil. It tolerates dry conditions, infertile soil, and rocky conditions.

Water

Common milkweed does not need watering except in the driest conditions. Water deeply, giving the plants between one to two inches of water, then wait until the top inch of soil is dry before watering again. Overwatering common milkweed can result in a lethal fungus.

Temperature and Humidity

Common milkweed tolerates a wide range of temperatures and humidity. But because it's native to eastern parts of the United States, it will not do well in extreme and extended heat or humidity.

Fertilizer

There's no need to fertilize common milkweed plants. Common milkweed tolerates poor soils.

(Video) Don't Plant Common Milkweed Until You Watch This - How It Spreads

Types of Related Milkweed Plants

Over 100 native species of milkweed plants are found in the United States, including common milkweed. In addition to common milkweed, here are some of the most popular types of milkweed within theAsclepiasgenus, which grow to different heights and bloom colors:

  • Butterfly weed(Asclepias tuberosa): one to two feet tall; light orange blooms native to the northeast United States
  • Swamp milkweed (Asclepias incarnate): four to five feet tall; mauve, pink, or white blooms native to the northeast and southeast United States
  • Sandhill milkweed (Asclepias humistrata): one to three feet tall; pink, lavender, or white blooms native to southeast United States
  • Showy milkweed (Asclepias speciosa): one to three feet tall; rosey-purple and pink blooms native to the western United States

Propagating Common Milkweed Plants

Propagating common milkweed by taking cuttings can be easier than dividing rhizomes because milkweed tends to grow deep taproots, which can be tricky to dig up. With cuttings, you can create new plants in a short period of time which is ideal if you want to get a quick start to creating butterfly garden. Here's how to propagate milkweed plants via cuttings:

  1. Take cuttings of common milkweed in the middle of the summer when stems are green. With a sharp, sterilized garden cutting tool, cut stems that are four inches long. Choose green stems with three to five leaf nodes.
  2. Remove the lower leaves of each stem and keep the top two pairs intact. Coat the bottom of the stems with a rooting hormone.
  3. Place stems standing up in potting medium that is an 80/20 mix of perlite to peat moss.
  4. Place pots in a shady cool spot out of any direct sunlight while the stem is forming roots. Keep the soil evenly and continuously moist.
  5. Transplant the cuttings into the ground within six to ten weeks.

How to Grow Common Milkweed From Seed

Common milkweed seeds scatter on their own right before the coming cold seasons so they can naturally encounter cold stratification. You can also scatter seeds directly in the ground in the fall so they can go through this process, planting them about one inch deep in the soil.

Be aware that when you start common milkweed seeds indoors, thel cold stratification process to increase the germination rate takes 30 days, so plan to start that process sometime in March. Here's how to start common milkwood seeds indoors:

  1. Although this step is optional, if you want to increase your seed germination rate, stratify the seeds first. The easiest way is to wrap seeds in a damp paper towel which is then put in a zippered plastic bag. Put the bag in the refrigerator where they will be undisturbed for about 30 days before planting in peat pots.
  2. Fill peat pots 3/4 of the way with seed-starting potting soil; moisten the soil until it is just damp.
  3. Place one or two seeds in each pot. Cover the seed with a 1/4 inch of soil.
  4. Water the seed from the bottom up. Put the peat pots on a flat pan and add 1/2 inch of water to the tray. The pots will absorb the water.
  5. Place the pots on a sunny sill, under grow lights, or in a greenhouse. Watch for sprouts within two weeks.
  6. Transplant the peat pots directly in the ground in the spring. The pots break down over time without disrupting the milkweed's roots.

Common Pests & Plant Diseases

The usual suspects are attracted to common milkweed, including milkweed bugs (which don't do too much harm, in fact), aphids, whiteflies, scale insects, spider mites, thrips, and leaf miners. Use a hose, spray from a bottle, or fingernails to scrape off the offenders. Snails and slugs also love young tender milkweed plants. Snail bait works well and won't harm monarchs, but as the plants grow, the snail problem minimizes.

Watch for fungus problems such as leaf spot, verticillium wilt, and root rot. Trim infected leaves and branches affected by leaf spot, but the other two fungus issues may be difficult to overcome.

FAQ

  • Is common milkweed good to plant in a border garden?

    Common milkweed spreads fairly aggressively, and some gardeners and local agencies advise to be careful where you plant it for this reason. It is too weedy and aggressive for most mixed border gardens unless you are specifically creating a butterfly garden. You can try containing the plant by putting it in the back of your garden where it has limited space to spread.

    (Video) Complete Guide to Butterfly Weed - Grow and Care, Asclepias tuberosa

  • What type of pesticides should I use on common milkweed?

    It is important not to use pesticides in a butterfly garden, as the same chemicals that kill destructive insects will also kill butterflies and their larva. Most gardeners find, though, that once a garden goes chemical-free, it establishes a good balance of beneficial, predatory insects, and provides songbirds with a source of food (many bird species consume large quantities of insects).

  • How do I plant common milkweed to attract butterflies?

    If you are planting common milkweed to encourage monarch butterflies, create a small patch of milkweed that includes at least six plants. Include a nearby water source for your butterflies; a birdbath or a large potting saucer filled with water will work fine. Planting other pollinator-friendly plants in a comprehensive butterfly garden is a good idea.

Watch Now: The Best Flowers for Butterflies

(Video) Let's Talk Milkweed (Asclepias) 🦋 Pro Talk with Sean at The Gardener's Center

Article Sources

The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. Milkweed can Cause Serious Poisoning. National Capital Poison Control.

  2. “5 Steps to Planting Milkweed Seeds Indoors.”Save Our Monarchs, https://www.saveourmonarchs.org/blog/5-steps-to-planting-milkweed-seeds?gclid=Cj0KCQiAoNWOBhCwARIsAAiHnEgGtjagcWTAaT_mMN2rh_I9jegbyCfswodF0IU9JABUI2TR_9YPNUkaAq69EALw_wcB. Accessed 5 Jan. 2022.

  3. “Yard and Garden: All about Milkweed.”News, https://www.extension.iastate.edu/news/yard-and-garden-all-about-milkweed

  4. James, David G. A Neonicotinoid Insecticide at a Rate Found in Nectar Reduces Longevity but Not Oogenesis in Monarch Butterflies,Danaus plexippus(L.). (Lepidoptera: Nymphalidae). Insects, 10(9): 276, 2019. doi:10.3390/insects10090276

    (Video) Swamp Milkweed will bring beauty, Butterflies and pollinators to your garden

FAQs

What are the best growing conditions for milkweed? ›

Best growing practices suggest milkweeds be planted in the sunniest parts of your yard or garden. If you have a choice of soil, most milkweed species thrive in light, well-drained soils with seeds planted a quarter-inch deep.

What is the easiest milkweed to grow? ›

Asclepias fascicularis (narrowleaf milkweed)

An easy-to-grow Western milkweed with pink/white blooms and skinny leaves. Narrowleaf milkweed grows in a wide range of soil conditions from garden soil to clay. Very drought tolerant, but can also survive seasonal flooding.

How do you take care of milkweed? ›

Common milkweed does not need watering except in the driest conditions. Water deeply, giving the plants between one to two inches of water, then wait until the top inch of soil is dry before watering again. Overwatering common milkweed can result in a lethal fungus.

How do you grow common milkweed? ›

Milkweed seed can be planted directly in soil, or started indoors. You can sow milkweed seeds by scattering them on the soil surface 1/4-1/2 inch apart, and then cover them with about 1/4 inch of additional soil. Water the area frequently after planting until plants become established.

How long does it take for milkweed to fully grow? ›

Ideally a sturdier stem is better. Cold stratified seeds should germinate and sprout within 10-15 days once planted. In total Milkweed from the day they are cold stratified to growth can take 40 plus days, so be patient!

How many milkweed plants should I plant? ›

To attract multitudes of monarchs to your garden, plant milkweed in groups of six or more, spacing plants or thinning seedlings to about 6 to 24 inches apart, depending on the species.

Where should you not plant milkweed? ›

It is not recommended to plant milkweed within 10 miles of the coast in central and northern California where milkweed did not occur historically. Instead, plant a variety of flowers native to your region that provide nectar from early spring through fall to support monarchs and other pollinators.

How do you keep milkweed alive? ›

An easy rearing method, which requires less daily care, is to place the larvae on milkweed whose cut stems are placed in water in narrow necked bottles – 2-liter plastic bottles work great. First, cut the milkweed stems twice under warm water; this will keep the milkweed fresh.

How do you take care of milkweed in the winter? ›

Cut back milkweed stalks in the late fall or winter, after they have produced seed pods and these seeds have had time to mature. Leave at least 6 inches of stalks to provide habitat for insects throughout the winter. Leaving stalks also gives you a marker so you know where your milkweed patch is.

What type of soil is best for milkweed? ›

Most milkweed species require moderately acidic soil with optimal PH levels between 4.8 and 6.8.

Does milkweed grow in sun or shade? ›

Sun and Drainage: Most milkweed does best and offers better blooms when planted in an area that receives full sun to light shade.

How long does milkweed take to flower? ›

A first year Asclepias incarnata plant (Swamp Milkweed) will have to wait another two years before it's blushing vivid pink with nectar-rich flowers. The first year the young milkweed builds its roots.

Can common milkweed grow in shade? ›

they can tolerate a bit of partial shade, Milkweeds do best in full sun. Any companion plants should have similar cultural needs. California Native Milkweed doesn't look very California Native in its small mailing pot when we mail it to you, especially if we ship it before June when the plant is dormant.

Where should you not plant milkweed? ›

It is not recommended to plant milkweed within 10 miles of the coast in central and northern California where milkweed did not occur historically. Instead, plant a variety of flowers native to your region that provide nectar from early spring through fall to support monarchs and other pollinators.

Why is milkweed a problem? ›

Tropical milkweed becomes a problem when planted in temperate areas where it does not die back in winter. A protozoan parasite of monarch butterflies, Ophryocystis elektroscirrha or OE for short, can travel with monarchs visiting the plants and become deposited on leaves.

How do you keep milkweed plants healthy? ›

Water at the base of the plants– this is less necessary if your plants have good air circulation. Hydrogen peroxide also adds more oxygen to the soil to prevent root rot. It can also prevent another common fungus that causes milkweed to wilt and die.

Does milkweed come back every year? ›

These native milkweed are perennials, meaning they come back year after year. Their aerial parts (flower, leaves, stem) die back but their rootstock remains alive throughout the winter. Cut back milkweed stalks in the late fall or winter, after they have produced seed pods and these seeds have had time to mature.

Videos

1. What You Should know BEFORE Planting MILKWEED
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2. Milkweed Crash Course | Milkweed Plant Basics
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3. How To Grow Milkweeds From Seed - Secrets! - Proven Method! - Tips & Tricks!
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4. Eric, milkweed dos and don'ts
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5. Swamp Milkweed - Asclepias Incarnata. Facts, Grow & Care
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6. Swamp Milkweed: Plant Care & Harvesting Seeds! Asclepias incarnata
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