The milkweed plant is important to many species of insects, particularly the monarch butterfly. Monarch caterpillars require this plant to reproduce. Learning how to grow the milkweed plant is easy, and in doing so, home gardeners can help monarch butterflies reverse their rapid population decline. Multiple varieties of the milkweed plant are native to many different parts of the United States. Home gardeners can find those suited for their particular geography and learn how to achieve the best results for their growth and reproduction.

milkweed plant flower

What Is The Milkweed Plant and What Are Its Main Uses?

With the scientific name of Asclepias, the milkweed plant is an American genus of herbaceous perennial, dicotyledonous plants, which includes more than 140 known species. Many ornamental varieties are native to the United States including the common milkweed, the butterfly weed, the swamp weed, and the antelope-horns milkweed.

The milkweed plant takes its name for the milky sap, which contains latex alkaloids and other complex compounds. Its wax-coated filaments have good insulation qualities and have been used for both thermal and acoustic insulation. The plant is grown commercially as a hypoallergenic filling for pillows, and its fibers are also used to clean up oil spills. Certain species are poisonous and can cause dermatitis for people and death for some animals.

Home gardeners can plant milkweed seeds in the fall, allowing them to germinate the following spring, or they can start seeds indoors with grow lights after a period of cold stratification.

The Main Varieties of the Milkweed Plant

  • Butterfly milkweed: Showcases lovely orange flowers in late spring.
  • Swamp milkweed: Reaches four feet high and blooms in the summer with pink flowers.
  • Whorled milkweed: Features fine leaves and little white flowers but is toxic to livestock.
  • Common milkweed: Sports dull, coarse, invasive, purple ball-shaped flowers.
  • Purple milkweed: Suffers from poor seed germination and weevil damage.
  • Balloon plant: Tops out at six feet by late summer with its lime green, spiky seed pods.
  • Tropical milkweed: Blooms attractive, red-orange flower clusters.

How to Grow the Milkweed Plant in Your Garden

Cold Stratification

To successfully germinate the milkweed plant from seed, gardeners must apply cold stratification. This allows the seed to break its natural dormancy by providing winter-like temperatures, which will help soften the seed’s hard casing. Place milkweed seeds in a moist paper towel inside a sealed bag and leave in the refrigerator for about a month.

Start Plants

After the cold stratification period, plant the seeds in two-to-four inch peat pots filled with quality potting soil that have been pre-watered. Place one or two seeds in each pot and cover with a quarter inch of soil. To water the seedling, place a pan of water under the peat pots and allow them to wick up the water. Water no more than once a day to prevent fungal growth.

Seedling Care

For the first several weeks, place your milkweed peat pots in a green house, under grow lights or near a sunny window. Be sure grow lights are near the soil to help the seedlings develop strong stems. Germination can take up to two weeks.

Seedling Tray

Gardeners may try to plant unstratified dry seeds in seed-starting soil in a greenhouse; however, germination rates may be much lower and longer with this method.

Outside Planting

One can plant seeds directly outside in late fall, allowing a natural winter to provide the required cold stratification. The spring sun and rain will help the seeds germinate on their own. Seeds will not germinate in hot temperatures.

Ongoing Care

The milkweed plant grows best in open areas and with full sunlight. Transplant seedlings when they are less than three inches tall. In many cases, transplantation will cause shock and the seedling will lose its leaves in order to establish a root system. Peat pots help lessen the shock.

The best time to transplant milkweed plants is in early spring after the local frost date. Once planted, water seedlings initially for a few days and then during dry spells.


Many varieties of milkweed plants exist, and gardeners in most areas of the United States can find a few kinds that will grow well in their area. Ongoing development and modernization has eliminated many native milkweed areas, causing up to a 90 percent decline of the monarch butterfly population. Home gardeners can help reverse this trend by including the milkweed plant in their landscapes and yards. Some caution needs to be taken as a few varieties can be toxic to nearby animals or household pets.

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