Milkweeds (Asclepias spp.) are the required host plants for caterpillars of the monarch butterfly (Danaus plexippus) and thus play a critical role in the monarch’s lifecycle. The loss of milkweed plants in the monarch’s spring and summer breeding areas across the United States is believed to be a significant factor contributing to the reduced number of monarchs recorded in overwintering sites in California and Mexico. Intensifying agriculture, development of rural lands, and the use of mowing and herbicides to control roadside vegetation have all reduced the abundance of milkweeds in the landscape. To reverse this trend, the North American Monarch Conservation Plan (published in 2008 by the tri-national Commission for Environmental Cooperation) recommends the planting of regionally appropriate native milkweed species.

Commercial sources of locally native milkweed seed are scarce throughout the monarch’s first generation spring breeding range in the southern United States and this limits opportunities to include milkweeds in regional restoration efforts.

In 2010, with support from the Monarch Joint Venture and a USDA Natural Resources Conservation Service Conservation Innovation Grant, the Xerces Society initiated a multi-state project to increase the availability of milkweed seed for large-scale restoration efforts in California, Nevada, Arizona, New Mexico, Texas, and Florida. Xerces is working with native seed producers and the Natural Resources Conservation Service (NRCS) Plant Materials Program to increase the production of local ecotype native milkweed seed and develop propagation guidelines for various milkweed species.

To further support this effort, the Xerces Society is:

• raising public awareness about their value for monarchs and native pollinators,

• developing guidelines on using milkweeds in habitat restoration,

• promoting the inclusion of milkweeds in large-scale restoration efforts, and

• working to build new markets for milkweed seed within the native seed industry.

For More Information
Click on the icons below to read about our milkweed seed increase project, California native milkweeds, and a guide to the native milkweeds of California.

Milkweed Population Survey
The Xerces Society, with support from the Monarch Joint Venture, has prepared a short web-based survey to gather information about the location of milkweed stands in the western states that potentially serve as important monarch breeding areas. If you know where milkweed grows, we’d appreciate you completing the survey.

Agency Partners

The NRCS Plant Materials Program develops innovative planting technology to solve the nation’s most important resource concerns and is a proven leader in conservation plant selection. The Plant Materials Program includes a network of 27 Plant Materials Centers and associated Plant Materials Specialists serving all 50 states and territories. Previous work between the Xerces Society and the NRCS Plant Materials Program has supported the restoration of thousands of acres of pollinator habitat nationwide.

In Florida and New Mexico, Xerces is working with the Brooksville Plant Materials Center and the Los Lunas Plant Materials Center to conduct an initial seed increase of select milkweed species. The seed stock that is produced will be transferred to private native seed producers for commercial-scale production.  Xerces is also working with the Great Basin Plant Materials Center in Nevada to utilize on-site milkweed populations as a source of initial seed stock for seed increase work in the Great Basin.

NRCS Plant Materials Program: http://plant-materials.nrcs.usda.gov/

Brooksville Plant Materials Center: http://plant-materials.nrcs.usda.gov/flpmc/

Los Lunas Plant Materials Center: http://plant-materials.nrcs.usda.gov/nmpmc/

Great Basin Plant Materials Center: http://plant-materials.nrcs.usda.gov/nvpmc/

Industry Partners

Hedgerow Farms

Narrow-leaved milkweed (Asclepias fascicularis) in production at Hedgerow Farms, Winters, California.

The Xerces Society and Hedgerow Farms of Winters, California, have developed a new source of native California milkweed seed for use in large-scale restoration projects across the Central Valley. Through this partnership, 70 pounds of narrow-leaved milkweed seed (Asclepias fascicularis) were produced during the 2010 growing season. Xerces continues to work with Hedgerow Farms to establish seed production field for additional California milkweed species.

Hedgerow Farms specializes in producing high quality seed of source-identified California native grasses, sedges, rushes and forbs, and also sells plug transplants. Hedgerow Farms’ plant materials are used for habitat restoration, agricultural revegetation, erosion control, and urban and rural landscaping. Hedgerow Farms also offers a seed mix developed with the Xerces Society for general pollinator conservation projects in California. www.hedgerowfarms.com

Native American Seed

Milkweed seedlings at the Native American Seed farm, Junction, Texas. Seeds were planted during April 2011.

Xerces has partnered with Native American Seed, one of the largest native seed producers in Texas, to increase the seed production of two milkweed species, antelope horns (Asclepias asperula ssp. capricornu) and green milkweed (Asclepias viridis). Both species are important host plants for spring migrating monarchs that arrive in Texas upon their return from overwintering sites in Mexico.

Native American Seed offers 100% native and locally harvested wildflower & grass seeds, plant materials that are invaluable for the preservation of a unique genetic diversity and for the restoration of ecosystems. www.seedsource.com

For more information about Xerces’ milkweed seed increase project, please contact Brianna Borders  (briannaxercesorg)  , Plant Ecologist