Common Milkweed Plant Profile

Attractive to Monarch Butterflies

milkweed plant

The Spruce / Adrienne Legault

Common milkweed (Asclepias syriaca) is a native herbaceous perennial whose main virtue is its appeal to butterflies—especially the monarch, which deposits its eggs on the milkweed. When the caterpillars hatch, they feed on the leaves of milkweed. Common milkweed plants grow to about 2 to 4 feet in height, with a thin, vertical growth habit. The long, oblong leaves are light green and grow to about 8 inches long. The stems and leaves bleed a milky sap when cut, which gives the plant its name. In late spring to mid-summer, fragrant clusters of pink-purple flowers appear. The flowers produce warty seed pods 2 to 4 inches long that split when ripe to cast many fine seeds to the wind.

milkweed plant
The Spruce / Adrienne Legault
closeup of milkweed
The Spruce / Adrienne Legault 
Botanical Name Asclepias syriaca
Common Name Milkweed, common milkweed
Plant Type Herbaceous perennial
Mature Size Two to four feet tall
Sun Exposure Full sun
Soil Type Any well-drained soil; tolerates clay soil and poor, dry conditions
Soil pH 4.8 to 7.2
Bloom Time June to August
Flower Color Pink, mauve, white
Hardiness Zones 3 to 9 (USDA)
Native Area Fields and roadsides of eastern North America
Toxicity Toxic to people

How to Grow Milkweed Plants

Plant milkweed about 18 inches apart; their rhizomatous roots will quickly fill in the space between plants. There's no need to fertilize milkweed plants, as they tolerate poor soils. Your biggest maintenance challenge will probably be in containing them. Asclepias syriaca spreads both via seeds and rhizomes, forming colonies.

At the very least, you may wish to remove the seed pods before they open. Otherwise, they will spread to 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.


Milkweed prefers full sunlight.


This plant prefers well-drained soil and performs well in dry conditions, as do many wildflowers.


Common milkweed does not need watering except in the driest conditions.

Temperature and Humidity

Tolerates a wide range of temperatures and humidity.


No feeding is necessary with this plant.

Propagating Milkweed Plants

Milkweed spreads easily via rhizomatous roots; cutting root sections and planting them so the roots are just buried will easily propagate the plants. Milkweed can also be grown easily from collected seeds planted about 1 inch deep in the garden.

Pruning Common Milkweed

Remove the seedpods from milkweed to prevent the seeds from spreading on the wind.

Planting for Monarch Butterflies

Milkweed is 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. The butterflies use the plants for all stages of their lifecycle, so watching the caterpillars feast on leaves, create their chrysalises, then mature and hatch into butterflies can be an entertaining and informative family activity. (But warn children about the toxic nature of milkweed leaves.) With careful observation, you may see all phases of the life-cycle in a single year, from eggs hatching into tiny caterpillars, to caterpillars magically transforming into butterflies, to butterflies laying new eggs.

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.

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, as well as providing songbirds with a source of food (many bird species consume large quantities of insects). Many of the most healthy gardens are those that are entirely free of chemical use.

monarch butterfly on a milkweed plant
Annie Otzen / Getty Images

Landscape Uses

This is not a particularly attractive plant, but in addition to its value in attracting butterflies, the seed pods can be used in dried flower arrangements. The flowers are also quite fragrant, and gardeners specializing in native species often grow milkweed. Milkweed has a history of medicinal use, but be aware that the leaves and the milk-like substance within are poisonous—it's this milky residue consumed by monarch butterflies that makes them bitter and repulsive to predators.

Milkweed spreads fairly aggressively, and many gardeners and local agencies warn against its use for this reason. It is too aggressive for most mixed border gardens unless you are specifically creating a butterfly garden.

milkweed plants
The Spruce / Adrienne Legault
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. 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

  3. Yard and Garden. All About Milkweed. Iowa State University Horticulture Extension.