Plant These Milkweed Species, Not Tropical Milkweed — A Region-by-Region Guide for Monarch Gardeners

Monarchs Are a Migration, Not Just a Butterfly

The U.S. Fish and Wildlife Service proposed threatened status for the monarch butterfly in December 2024. Researchers estimate that 970 million monarchs have vanished since 1990 — roughly a 90% collapse — driven by habitat loss, pesticide use, and climate change. Milkweed loss is front and center in that story. Monarch caterpillars can only eat milkweed, and without it, no eggs survive to become butterflies.

Planting milkweed genuinely helps. But here’s what most planting guides skip: monarchs don’t have a fixed home. They complete a multi-generational migration that spans thousands of miles, and they need milkweed along the entire route — not just at the end of it. Which species you plant matters, and it depends on where you live.

There are 73 native milkweed species in the United States. Monarchs use about 30 of them regularly. This guide cuts through the list and gives you the right picks by region — plus an honest look at why the tropical milkweed sold at most garden centers can actively undermine the migration you’re trying to support.

Two Populations, Two Routes — What Your Garden Is Part Of

Eastern monarchs complete one of the longest insect migrations on Earth, traveling up to 3,000 miles between their overwintering forests in central Mexico and their summer breeding grounds across the Midwest and Northeast. No single butterfly makes the full round trip. The spring generation leaves Mexico depleted and arrives in Texas in early March, looking for the first emerging milkweed to lay eggs. Those caterpillars become the next generation of adults, which push further north, and so on — it takes three to five generations to reach Minnesota and southern Canada by midsummer. The single “super-generation” born in late summer then makes the full return flight to Mexico.

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Western monarchs follow a shorter but equally fragile route — breeding across the Intermountain West and Pacific Northwest, then overwintering in coastal California groves. This population dropped from 233,394 in the fall of 2023 to just 9,119 in the fall of 2024, making it the second-lowest count since surveys began in 1997.

What this means practically: gardeners in Texas are restocking the migration’s first generation — without Texas milkweed in spring, the breeding front never reaches the Midwest. Gardeners in Ohio are fueling the summer nursery. Gardeners in California are adjacent to the western population’s overwintering sites. Every garden along the route is a waystation. The species you plant should match the ecological role your region plays.

Milkweed by Region: Which Species to Plant

The table below gives the top choices by region. Detailed notes on each follow.

Midwest and Northeast

This is the breeding heart of the eastern migration. Common milkweed (Asclepias syriaca) is the workhorse — 4 to 6 feet tall, spreading by underground rhizomes to form the colony-sized patches monarchs strongly prefer for egg-laying. A USDA Agricultural Research Service study of nine native Iowa milkweed species found that A. syriaca and swamp milkweed (A. incarnata) averaged the highest egg counts, confirming what most growers already suspect: bigger patches of these two species get the most use.

Swamp milkweed (A. incarnata) is the choice for wet corners — rain gardens, pond edges, or any low spot that stays damp. It grows 4 to 5 feet tall with mauve-pink flowers and a long bloom window. Butterfly weed (A. tuberosa) rounds out the planting with its compact drought-tolerant form (1 to 3 feet, vivid orange-yellow blooms) for drier, well-drained areas. Note that A. tuberosa lacks the milky sap characteristic of other milkweeds — this doesn’t reduce its value as a host plant, but it does affect identification.

For growing A. tuberosa in detail — establishment timelines, soil requirements, and its tap-rooted habit — see our butterfly milkweed growing guide.

Southeast (Zones 7–9)

Butterfly weed and swamp milkweed are the most widely available and easiest to establish across the Southeast. Green milkweed (A. viridis) adds a lower-growing native option suited to open meadows and roadsides. A. tuberosa handles the heat and humidity of this region better than most — its preference for dry, well-drained soil is an advantage in Southeast gardens that tend toward summer drought stress.

Zone 7 is the critical threshold for tropical milkweed concerns (covered below). If you’re in zones 7 through 9, replacing any existing tropical milkweed with these natives is more urgent than in colder zones.

South-Central and Texas

Texas is where the spring migration refuels. Overwintered monarchs arrive from Mexico in early March, depleted, and begin laying eggs on the first emerging milkweed. Their offspring become the generation that populates the Midwest — so what happens in Texas in March shapes the entire northern breeding season. Texas Parks and Wildlife documents two fall migration routes through the state: a 300-mile-wide inland corridor from Wichita Falls to Eagle Pass (late September through early November) and a second coastal route. Both directions require milkweed on the ground.

More than 35 milkweed species are native to Texas. Green antelopehorn milkweed (A. viridis) is the most ecologically important for monarchs in the central and eastern parts of the state — it’s found on roadsides and prairies and is the species monarchs encounter first on spring arrival. Antelope horn milkweed (A. asperula) suits dry rocky soils in the Hill Country and west Texas. Zizotes milkweed (A. oenotheroides) handles sandy soils. All three are difficult to find at mainstream nurseries — seek native plant societies or Texas-specific native plant retailers for seeds or plugs.

Intermountain West and Pacific Northwest

Showy milkweed (A. speciosa) is the top restoration choice for all western states outside California — Monarch Watch recommends it as the primary species for this region. It earns that status: large pink globe-shaped flower clusters, a wide ecological range from Oregon to New Mexico, and tolerance of varied soils. Broadleaf milkweed (A. latifolia) serves as a secondary option at lower elevations in drier sites. Given the western population’s near-record collapse, any establishment of these two species adds measurable habitat in a region where milkweed is genuinely scarce.

California

California supports 15 native milkweed species across its ecosystems. For most home gardens, narrowleaf milkweed (A. fascicularis) is the easiest entry point — drought-tolerant after establishment, adaptable to sandy or clay soils, and widely available through native plant nurseries. Showy milkweed (A. speciosa) works well in northern and central California. Both are available as seeds (plant April through July) or starts (install March through August). Water new plants deeply once or twice a week for the first year; after establishment, twice monthly is usually enough.

To find California-native suppliers by zip code, the California Native Plant Society’s Calscape tool (calscape.org) is the most reliable source.

Why Tropical Milkweed Undermines the Migration

Tropical milkweed (Asclepias curassavica) — the orange-and-yellow variety sold at most big-box garden centers — is not a native North American species. Monarchs will readily lay eggs on it, which makes it easy to assume it helps. It’s one of the most common discoveries that stops gardeners cold: “But I can see eggs on it — isn’t that good?” The problem is biological, not behavioral, and it operates through two separate mechanisms.

The OE Parasite Builds Up Without a Reset

Ophryocystis elektroscirrha (OE) is a protozoan parasite that infects monarchs. An infected butterfly deposits microscopic spores on milkweed leaves while feeding. When caterpillars hatch and eat those leaves, they ingest the spores and become infected. Heavily infected adults have lower migration success, reduced flight ability, shorter lifespans, and lower mating success — each one a meaningful reduction in the migration’s carrying capacity.

Native milkweed dies back in winter across most of its range. When the plant dies, the spore load on that season’s leaves dies with it. Next spring’s new growth starts clean. Tropical milkweed doesn’t die back in zones 7a and warmer — it stays leafy year-round, and OE spores accumulate generation after generation on the same plants. By late summer, milkweed that started the season lightly contaminated can carry a heavy spore load. The University of Wisconsin Extension explicitly recommends avoiding tropical milkweed in zones 7a or warmer for exactly this reason, and advises against overwintering potted plants indoors, which creates the same accumulation problem.

It Disrupts Migration Timing

Fall migration requires monarchs to enter diapause — a reproductive pause that redirects energy from breeding to the long flight south. A peer-reviewed study published in Insects tested what happens when migrating monarchs encounter tropical milkweed. Among wild-caught fall migrants, females exposed to tropical milkweed showed significantly greater egg development than those exposed to native milkweed or no milkweed at all. In laboratory conditions rearing caterpillars on tropical milkweed, 55% of females (versus 20% of males) became reproductively active — a state incompatible with completing a 3,000-mile migration. The researchers described this outcome as “migratory dropout”: energy that should fuel the flight to Mexico is spent on reproduction instead.

If You Already Have Tropical Milkweed

In zones 6 and colder, tropical milkweed will die back in winter naturally — the OE accumulation problem is minimal. If you’re in zones 7 through 10, cut your tropical milkweed to ground level around Thanksgiving and again near Valentine’s Day. This clears the accumulated spore load without permanently removing the plant. Over the following growing season, replace it with one of the native species from the regional guide above.

Planting for Maximum Impact

A few practical notes on getting the most out of your milkweed planting:

Plant in clusters, not singles. USDA research confirms monarchs show stronger laying preferences for abundant patches over isolated plants. Three to five plants of the same species is a meaningful unit; ten or more is better. A single isolated stem rarely attracts females.

Source locally. Regionally native ecotypes are better adapted to your local soils and pest pressure. Search plantmilkweed.org or your state’s native plant society for vetted sources. Big-box nurseries occasionally stock native milkweed, but check the tag carefully — Asclepias curassavica is often labeled simply as “milkweed” or “butterfly plant.”

Most species need full sun. Six or more hours of direct sun is the baseline for most milkweeds. Swamp milkweed (A. incarnata) is the exception — it tolerates partial shade and is the only widely available species that does.

Skip pesticides in and around milkweed. Neonicotinoid-treated plants (standard at many large retailers) can harm or kill caterpillars even weeks after purchase. Ask your nursery directly whether plants have been treated. For broader habitat planning, our caterpillar host plant guide covers additional native species that support the full butterfly lifecycle beyond milkweed, and our pollinator garden by zone guide maps native nectar plants that fuel adult monarchs during migration.

Pair with late-summer nectar plants. Migrating adults need fuel. Native goldenrod and New England aster are the most important fall nectar sources in the eastern migration corridor — bloom timing aligns almost exactly with the southbound flight.

For details on growing swamp milkweed in your garden — including soil preparation, division, and overwintering — our full care guide covers the species from planting through establishment.

FAQ

Does butterfly weed (Asclepias tuberosa) support monarchs? Yes — monarchs will readily lay eggs on it, and it’s an excellent host plant in dry, well-drained conditions. Its one quirk is slow establishment from seed; bare root transplants typically perform better. See the butterfly milkweed growing guide for establishment details.

Is common milkweed (Asclepias syriaca) too aggressive for a small garden? It spreads by underground rhizomes and can colonize several feet in a season. In a small border, install a root barrier (like those used for bamboo) at 12 inches depth, or grow it in a contained raised bed. The spreading habit is ecologically valuable — monarch females prefer large patches — so if you have the space, let it spread.

Can I grow tropical milkweed in zone 5? In zone 5 it dies back in winter, which limits OE buildup. But native alternatives — A. syriaca, A. incarnata, A. tuberosa — are all hardy, better adapted to your local conditions, and don’t risk disrupting migration timing in any zone.

How long does milkweed take to establish from seed? Most native milkweeds bloom in year two or three from seed. For faster results, start with potted native plugs. Seeds of A. tuberosa in particular benefit from cold stratification — 4 to 6 weeks at 40°F before sowing — to break dormancy reliably.

Sources

• Monarch Watch — Milkweed Regions & Seed Needs
• Penn State Extension — Monarchs and Milkweed
• University of Wisconsin Horticulture Extension — Tropical Milkweed (Asclepias curassavica) (hort.extension.wisc.edu)
• Oberhauser et al. 2019 (Insects, PMC6724006) — Exposure to Non-Native Tropical Milkweed Promotes Reproductive Development in Migratory Monarch Butterflies (pmc.ncbi.nlm.nih.gov)
• USDA Agricultural Research Service — Which Milkweeds Do Monarch Butterflies Prefer?
• UC Agriculture and Natural Resources — Save the Monarch Butterfly: Grow California Native Milkweeds
• Texas Parks & Wildlife Department — Monarch Butterfly and Insect Pollinators
• U.S. Fish & Wildlife Service — Monarch Butterfly Proposed for Endangered Species Act Protection (December 2024), fws.gov
• National Wildlife Federation — Twelve Native Milkweeds for Monarchs