Project Milkweed


Returning Essential Wildflowers to America’s Landscapes

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 life cycle. 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. Agricultural intensification, 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 help offset the loss of monarch breeding habitat, 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. However, a scarcity of milkweed seed in many regions of the United States means limited opportunities to include the plants in regional restoration efforts.

To address this seed shortage, the Xerces Society launched Project Milkweed, with support from the Monarch Joint Venture, a USDA Natural Resources Conservation Service Conservation Innovation Grant, and private foundations. In collaboration with the native seed industry, the USDA-NRCS Plant Materials Program, and community partners, Xerces is producing new sources of milkweed seed in areas of the monarch’s breeding range where seed has not been reliably available: California, the Great Basin, Arizona, New Mexico, Texas, and Florida. To further support this effort, the Xerces Society is raising public awareness about milkweeds’ value to monarchs and native pollinators and promoting the inclusion of milkweeds in habitat restoration efforts.


Milkweed Seed Finder

Monarchs need milkweed! Locate regional suppliers of milkweed and milkweed seed using our Milkweed Seed Finder.

Milkweeds: A Conservation Practitioner’s Guide

This Xerces Society guide shows how to bring back our milkweeds and restore habitat for monarch butterflies. Milkweeds: A Conservation Practitioner’s Guide is a first-of-its kind manual on large-scale milkweed seed production, nursery propagation, and field restoration of the plants. Learn more.

Managing Milkweed Crop Pests

Increasing the availability of milkweeds is critical to monarch conservation, but seed production can be difficult. While monarchs are the most well-known milkweed specialists, other specialist milkweed-feeding insects can cause damage to valuable milkweed crops. Our guide provides management strategies for dealing with common milkweed pests including aphids, milkweed bugs, and milkweed beetles. Learn more.

Native Milkweed in California: Planting and Establishment

Native Milkweed in California: Planting and Establishment

With the dramatic decline of western monarchs, successful planting and establishment of native milkweed in California takes on increased significance. This fact sheet provides clear instructions on how to establish milkweed from seed, transplants, and rhizomes, as well as where to plant for optimum benefit to monarchs. Learn more.

Regional Milkweed Guides

A series of regional guides to the native milkweeds of North America, developed in cooperation with the USDA Natural Resources Conservation Service:

Native Milkweeds
Great Basin
Native Milkweeds
Central U.S.
Native Milkweeds
Native Milkweeds
Native Milkweeds
Native Milkweeds
Desert Southwest
Native Milkweeds


Educational Brochures

The Florida Museum of Natural History, in collaboration with the Xerces Society, the Butterfly Conservation Initiative, and the U.S. Forest Service, has produced three educational brochures that feature information about monarchs and milkweeds. One side of the brochure describes the plight of the monarch and encourages the planting of regionally appropriate milkweed species, while the second side showcases larvae of other butterfly species and their associated host plants.

Southeastern U.S. Eastern U.S. Northern Great Plains


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 has also worked 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.



Industry Partners

Hedgerow Farms

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

The Xerces Society and Hedgerow Farms, Inc. of Winters, California, have made significant strides in increasing the availability of native California milkweed seed for use in large-scale restoration projects across the Central Valley. To date, Hedgerow has produced nearly 1,000 pounds of milkweed seed (Asclepias eriocarpa, A. fascicularis, and A. speciosa) and has also launched production of heartleaf milkweed (A. cordifolia).

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.

Native American Seed

Asclepias asperula and Asclepias viridis seed production field at the Native American Seed Farm, Junction, Texas.

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.

Community Partners in Arizona

Arizona Western College
During 2012 – 2013, Xerces worked with Arizona Western College to propagate rush milkweed (Asclepias subulata) and conduct an initial seed increase. This unique, desert-adapted species has photosynthetic stems, is nearly leafless, and blooms several times per year. Under the guidance of Environmental Biology professors Ted Martinez and Megan Lahti, students established and maintained a seed production field, monitored the plants’ use by monarch and queen butterflies, and harvested and cleaned seed. The seed used to initiate this grow-out was wild-collected by the Desert Botanical Garden.


Painted Lady Vineyard

Asclepia asperula seedling production at Greenheart Farms.

The Painted Lady Vineyard in Skull Valley is working with the Xerces Society to produce seed of spider milkweed (Asclepias asperula ssp. asperula). This species grows in open woodlands, chaparral, grasslands, and along roadsides, and bears striking ball-shaped clusters of purple and green flowers. The Vineyard and volunteers have established a seed production field, using seedlings produced by Greenheart Farms in Arroyo Grande, California.