MONARCH BREEDING HABITATS: A GUIDE
WHY YOUR GARDERN MATTERS
The monarch butterfly (Danaus plexippus) faces an uncertain future, but gardeners across North America hold a key to their recovery.
Our recent curation of over 275,000 monarch activity images worldwide reveals the dominant list of nectar plants used by monarchs that will be crittical to help them thrive.
Additionally, it is now known that early-season breeding habitats can boost annual monarch populations by up to 144%.
Your garden could be part of this success story.

MONARCH NEEDS:
Monarchs have two distinct life-forms with unique dining preferences.
Adult butterflies need energy-rich nectar from flowers to fuel their journeys.
Juvenile caterpillars are specialists—they only survive on milkweed (Asclepias species).
While some monarchs live year-round in Florida and Hawaii, migrating monarchs travel thousands of miles and depend entirely on gardeners like you to provide stepping stones of habitat along their routes.

BREEDING HABITATS:
Creating a monarch breeding habitat is straightforward:
6-10 milkweed plants (for egg-laying and caterpillar food)
6-10 nectar plants of various species (for adult butterfly fuel)
Ideal: a 50/50 ratio of host plants to nectar plants
Habitats roughly 300 feet apart attract monarchs as they migrate—keeping them longer in a collaborative neighborhood.
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TOP NECTAR PLANTS
Based on our curation of over 239,000 US monarch observations
Our research identified the most visited nectar sources.
FAVORITES in order of dominance:
Milkweed (Asclepias) - pulls double duty as nectar and host plant
Butterfly Bush (Buddleja)
Zinnia
Lantana
Goldenrod (Solidago)
Asters (Symphyotrichum)
Thistle (Cirsium)
Joe Pye Weed (Eutrochium)
Blue Mistflower (Conoclinium)
Boneset (Eupatorium)
Blazing Star (Liatris)
Clover (Trifolium)
Mexican Sunflower (Tithonia)
Coneflower (Echinacea)
Salvia

These genera thrive across USDA zones 2-11 enabling gardeners throughout the continental United States to participate in creating breeding habitats.
All of these genera contain native species.

Each genera on the above list have more than 1000 entries in our database.
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THE SCIENCE BEHIND SUCCESS
Monarchs navigate using scent receptors across their bodies to detect flowering plants from up to 125 meters away.
When nectar plants bloom, they broadcast an "olfactory plume" that draws monarchs in for fuel.
Here's the crucial part: if monarchs find only nectar plants, they'll refuel and continue their journey.
But if they discover milkweed nearby, they'll likely stay to lay eggs—boosting the next generation.

TIMING YOUR GARDEN
For Nectar Plants: these must be blooming during your area's primary monarch migration periods.
For Milkweed: these don't need to be flowering when monarchs arrive—just healthy and ready to support eggs and caterpillars.

MAKING IT HAPPEN
Start small if needed.
Even a modest habitat following the 50/50 habitat planting formula can make a difference.
Consider partnering with neighbors to create habitat corridors that accommodate monarchs' natural movement and migratory patterns.

Remember: early-season breeding activity has the greatest population impact.
By giving monarchs what they need when the season begins, your garden becomes part of a conservation success story that spans an entire continent.
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Analysis of monarch habitat preferences continues, and plant recommendations may be updated as new data becomes available.
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Midwest and Eastern Population
(Additional regionally specific information will be added.)
If you live in any of the Midwest's five states that make up the Southern Great Plains, than planting fall flowering habitats are needed now, as it is an opportunity for migrating adults Monarchs to create another generation that will then head to the overwintering sites in Mexico.*

*Citation: Midwest Association of Fish and Wildlife Agencies. 2023

Many Asclepias retain their biomass into the fall, making them a potential fall host plant. While it may be an incomplete list, these milkweed were suggested as fall flowering in each of the five states:
Texas: Asclepias tuberosa (Butterfly Milkweed), Asclepias linearis (Slim Milkweed), and Asclepias oenotheroides (Zizotes Milkweed)

Oklahoma: Asclepias verticillata (Whorled Milkweed)
Kansas: Asclepias verticillata (Whorled Milkweed), Asclepias syriaca (Common Milkweed)
Missouri: Asclepias verticillata (Whorled Milkweed), Asclepias syriaca (Common Milkweed), Asclepias tuberosa (Butterfly Milkweed), and Asclepias incarnata (Swamp Milkweed)
Arkansas: Asclepias verticillata (Whorled Milkweed), White Milkweed (Asclepias variegata)

It is worth noting, that a study of Asclepias* conducted in Iowa revealed that Asclepias speciosa, sullivantii, syriaca, and tuberosa produced the best larval survival results, with A. syriaca performing the best overall.
*https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2018.00169/full

If you live in a state east of the Rocky Mountains, and in the Great Plains, your habitat will likely attract Monarchs for breeding. Three to four generations are created during their breeding season in all these states. As few as six plants in an urban, suburban, or rural garden may attract monarchs to feed, but more plants are needed to create a truly sustainable habitat.
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If you live in California, you are very likely in a position to create a monarch habitat. A viable habitat consists of a 50% milkweed plants (Asclepias) and 50% nectar plants comprised of 8-10 milkweed plants and 8-10 nectar plants of species that bloom during your area's primary migration period. They will use habitats during each stage of their migration. The Western migrating population is in serious decline and may, or may not, recover (for information go to https://onlinelibrary.wiley.com/doi/10.1111/ele.13816). Providing viable habitat in suburban, urban, and rural gardens may aid in their recovery -- either contributing to a permanent localized population or an uncertain contribution to the recovery of the migrating population. Either way? Put plants in the ground.

Spring Habitat: Monarchs will migrate through Santa Cruz, San Mateo, Santa Clara, Monterey, San Benito, and parts of San Luis Obispo Counties seeking habitat for creating the first generation of butterflies. In southern CA they will migrate inland from the coast in Santa Barbara, Ventura, and LA Counties. This is an important stage in their development.
Providing Monarch habitat suitable to support the spring migration sets the stage for the development of a larger population.
Caterpillars raised early add to that year's population growth throughout that season -- each insect producing 3-4 more generations of Monarchs.

Fall Habitat: The last generation of Monarchs in California is typically created in inland areas during late summer to early fall.
This area includes counties in the Central Valley (e.g. Sacramento, San Joaquin, and Stanislaus),
as well as parts of the Sierra Nevada foothills and other inland regions where milkweed is still available.
The Sierra Nevada foothills include: Placer County, El Dorado County, Amador County, Calaveras County, Tuolumne County, Mariposa County, Madera County,
Fresno County, Tulare County, Nevada County, and Yuba County.

Habitats between migrations: During the summer months Monarchs can be found in many counties across California.
Central Valley counties: Sacramento, San Joaquin, Stanislaus, Merced, Fresno, Kings, Tulare, Kern.
Sierra Nevada foothills counties: Placer, El Dorado, Amador, Calaveras, Tuolumne, Mariposa, Madera.
Coastal and near-coastal counties: Humboldt, Mendocino, Sonoma, Marin, San Francisco, San Mateo, Santa Cruz, Monterey, San Luis Obispo, Santa Barbara, Ventura,
Los Angeles, Orange, San Diego.
Inland counties: Shasta, Tehama, Butte, Yuba, Sutter, Yolo, Solano, Contra Costa, Alameda, Santa Clara.
Southern California inland counties: Riverside, San Bernardino, Imperial

If you live in Northwest, you are very likely in a position to create a summer-breeding Monarch habitat. 
A viable habitat consists of a 50% milkweed plants (Asclepias) and 50% nectar plants comprised of 8-10 milkweed plants and 8-10 nectar plants of species that bloom during your area's primary migration period. Key areas where Monarchs are found include: 
Oregon: Willamette Valley (Lane, Linn, Benton, Polk, Marion, Yamhill counties), Columbia River Gorge area (Hood River, Wasco counties), and 
Southern Oregon (Jackson, Josephine counties) 
Washington: Eastern Washington (Klickitat, Yakima, Benton, Walla Walla counties) and Puget Sound region (King, Pierce, Thurston counties) 
Idaho: Southwestern Idaho (Ada, Canyon, Owyhee counties), and North-central Idaho (Nez Perce, Latah counties)

Milkweed Host plants:
Asclepias (DO NOT plant A. curavassica, it is harmful to Monarchs)
Asclepias amplexicaulis
Asclepias asperula
Asclepias californica
Asclepias cancellata
Asclepias cordifolia
Asclepias curtissii
Asclepias eriocarpa
Asclepias erosa
Asclepias exaltata
Asclepias fascicularis
Asclepias hirtella
Asclepias humistrata
Asclepias incarnata
Asclepias lanceolata
Asclepias longifolia
Asclepias nivea
Asclepias obovata
Asclepias oenotheroides
Asclepias physocarpa
Asclepias purpurascens
Asclepias semilunata
Asclepias speciosa
Asclepias subulata
Asclepias subverticillata
Asclepias sullivantii
Asclepias syriaca
Asclepias tomentosa
Asclepias tuberosa rolfsii
Asclepias variegata
Asclepias verticillata
Asclepias vestita
Asclepias viridiflora
Asclepias viridis

PD image courtesy of:
Perlick Laure, USFWS

CC0 images courtesy of
Lila
Zygy