Orange and black Monarch Butterfly with Swamp MilkweedOrange and black Monarch Butterfly with Swamp Milkweed

Saving The Monarch Butterfly By Planting Milkweed

By David Salman, High Country Gardens Chief Horticulturist

Monarch butterflies (Danaus plexippus) are perhaps the most well-known and beloved butterflies in North America. A ubiquitous sight in gardens, prairies, and natural areas from coast to coast, their arrival in northern states and Canadian provinces is viewed by many as a welcome sign of the change in seasons from spring to summer. Renowned for their long-distance seasonal migration and spectacular winter gatherings in Mexico and California, the monarch butterfly population has recently declined to dangerously low levels. In the 1990s, hundreds of millions of monarchs made the epic flight each fall from the northern plains of the U.S. and Canada to sites in the oyamel fir forests in central Mexico, and more than a million monarchs overwintered in forested groves on the California coast. Now, researchers and community scientists estimate that only a fraction of the population remains—a decline of approximately 80% has been seen in central Mexico and a decline of 99% has been seen in coastal California. The Xerces Society

It's truly astounding that our beloved Monarch butterfly is imperiled and faces the real threat of extinction. As development continues to take the place of natural landscapes, agribusiness continues to expand the use of herbicide- and pesticide-intensive crops, and climate change causes natural disasters, we are now seeing direct effects on the health of our natural world and the creatures that live in it.

As gardeners, we can and must make a concerted effort to reverse the loss of Monarch Butterfly habitat by planting Milkweed (Asclepias). Our gardens can help feed the Monarchs put in peril by the disregard for our planet and our environment.

There is increasing interest within the gardening community regarding butterfly plants, particularly Milkweed, and the plight of the Monarch butterfly. Thank goodness for this. Replanting Milkweed and sowing Milkweed seeds in residential and community gardens as well as in farmland will help to replenish populations of this plant genus lost to industrial agricultural practices. This is essential to creating a habitat for Monarchs, and this beloved migratory butterfly species' survival.

A Monarch caterpillar eating the leaves of a Milkweed (Asclepias) plant.A Monarch caterpillar eating the leaves of a Milkweed (Asclepias) plant.
A Monarch caterpillar eating the leaves of a Milkweed (Asclepias) plant.

Monarchs & Milkweed

Like many butterfly and moth species, Monarch butterflies have very specific plant needs when it comes to feeding their caterpillars. Species of Asclepias (Milkweed) are the only plants on which Monarch caterpillars will feed. The milky, bitter sap of Asclepias is the essential ingredient that adult Monarch butterflies utilize to protect themselves from being eaten by birds and other insect predators.

Each caterpillar will eat 20 or more milkweed leaves before maturing into a Butterfly. The more Milkweed you plant, the better!

There are many species of Asclepias, a widespread genus native to landscapes throughout North America. It is recommended that we concentrate our efforts on growing five primary non-tropical species of Milkweed:

Orange Butterfly Weed (Asclepias tuberosa) - a tap-rooted species that requires a fast-draining sandy soil, unless you plant the clay form or 'Western Gold' forms which grow in uncompacted, non-moist clay soils.
Showy Milkweed (Asclepias speciosa) - a fast growing stoloniferous species from the western US with large pink flower heads. It is also one of the easiest Asclepias species to grow, especially for beginner gardeners. It is well-adapted to most soil types (including clay), extremely cold hardy to USDA zone 3, and tolerates both dry and wet soil conditions. Naturalizes readily to provide even more caterpillar food and flower nectar.
Common Milkweed (Asclepias syriaca) - a fast growing stoloniferous species with large pink flower heads. Naturalizes readily to provide even more caterpillar food and flower nectar.
Swamp Milkweed (Asclepias incarnata) - an attractive species with fibrous roots and pink or white flowers that grows in swampy to medium-moist soils.
Sullivan's Milkweed (Asclepias. sullivantii) - a rarer Mid-Western species that is slowly stoloniferous with large pink flower heads.

Showy Pink Milkweed (shown at the top of the page) is a widely distributed species in North America, with populations occurring over most of the western US and Canada. It is also one of the easiest Asclepias species to grow, especially for beginner gardeners.

Here are some advantages to planting Showy Pink Milkweed:

  • Well-adapted to most soil types (including clay)
  • Extremely cold hardy to USDA zone 3
  • Tolerates both dry and wet soil conditions
  • Naturalizes readily to provide even more caterpillar food and flower nectar
Orange Butterfly Weed (Asclepias tuberosa) and Monarch ButterflyOrange Butterfly Weed (Asclepias tuberosa) and Monarch Butterfly
Orange Butterfly Weed (Asclepias tuberosa) is an especially showy member of the genus. Butterfly Weed has attractive, bright orange flowers in late spring and is a favorite nectar source for bees and butterflies.
California Narrow Leaf Milkweed (Asclepias fascicularis)California Narrow Leaf Milkweed (Asclepias fascicularis)
California Narrow Leaf Milkweed (Asclepias fascicularis) is a western native species of Asclepias grown for its large white flowers and long, showy narrow leaves. Easy to grow in a wide range of soils, this variety is recommended for use in the West.

Growing Milkweed In The Garden

Growing Milkweed is a delight in the garden. Their colorful flower clusters and sweet fragrance will easily earn a place among your favorite perennials. For the ornamental garden, Orange Butterfly Weed, Swamp Milkweed, and Sullivan's Milkweed are considered the best varieties, as they spread more gently. Showy Milkweed and Common Milkweed are aggressively stoloniferous (spreading by underground roots), so we recommend planting these in gardens where they will have space to naturalize, or planting in peripheral areas of the landscape where they can be free to spread. Consider planting along fencelines, drainage ditches, property borders, or even dedicating a section of your lawn to a meadow-style pollinator garden.

To learn more about how to grow Milkweed, from potted plants or from seed, see our guide:

Plant Milkweed For Monarchs

 

Text by David Salman. © All articles are copyrighted by High Country Gardens. Republishing an entire High Country Gardens blog post or article is prohibited without permission. Please feel free to share a short excerpt with a link back to the article on social media websites, such as Facebook and Pinterest.