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