When to plant milkweed in Texas

In Texas, sow native milkweed seed in the fall. The Native Plant Society of Texas says “Fall is the best time for planting milkweed seeds,” and the reason is the spring pass: monarchs arrive from Mexico in early March “seeking emerging milkweeds,” so the plants need to be in the ground and rooting before then; whether they are up and green by early March is the open question below.¹² Which milkweed to sow depends on where in the state you are.

Why fall, and why March is the deadline

Texas Parks and Wildlife: “Early each March overwintering monarchs begin arriving from their overwintering grounds in Mexico. Seeking emerging milkweeds, they move through Texas laying eggs before dying.”² Monarch Joint Venture puts the first generation’s eggs “from late March through April in the southern United States and northern Mexico.”³ The dated records people sent to Journey North in spring 2025 agree: eggs on a milkweed sprout at Montgomery on 8 March, at Driftwood on 12 March, and at Glen Rose on 17 March, where the observer found nine eggs “on small antelope horn milkweed sprouts.”⁴

A milkweed planted in March is not up in March. A milkweed sown the previous fall has its roots down and comes up on its own schedule. That is the whole argument. Texas Parks and Wildlife’s statement is statewide, “they move through Texas laying eggs,” but the dated egg records above are from Montgomery, Driftwood and Glen Rose; far West Texas, where the record is thin, and the coast, where some monarchs stay all year, are different cases, and the Texas page covers them.²

Fall sowing is simple. The Native Plant Society’s method: “Scatter the seeds and use your rake to gently work them into the soil.”¹

If you missed the fall

Seed sown at other times wants a cold, damp rest first. The Lady Bird Johnson Wildflower Center, for green milkweed: “Soak seed overnight in water. Cold moist stratification for 14-30 days enhances germination to greater than 60 percent.”⁵ Zizotes gets the same: “Soak seed overnight then cold moist stratify in the refrigerator for 14-30 days.”⁶ A 2015 article in Texas Parks and Wildlife’s Eye on Nature newsletter adds two things: plant “in a deep container (most species have a long taproot),” and “be patient: it may take a milkweed several years to reach reproductive maturity.”⁷ The same article notes that native milkweeds “are sometimes available at local nurseries as young, potted plants,” which is the other way to have a rooted plant by March.⁷

Nursery plants in pots go out after the freeze risk has passed, and that date is local. For Austin the median last freeze at Bergstrom Airport is 12 March, with one year in ten later than 2 April; the Austin calendar has the three-station table.⁸ We have not yet built the same record for other Texas cities, so this page does not print freeze dates for them. NOAA publishes the 1991–2020 normals for every long-running station.

Which milkweed, by region

Texas Parks and Wildlife’s identification guide lists 37 kinds of Asclepias recorded in the state, only one of them non-native, and gives each one’s habitat by ecoregion.⁹ Monarch Joint Venture names three of them as “the most important host plants for Generation 1 monarchs in the southern US”: Asclepias oenotheroides (zizotes), Asclepias viridis (green milkweed) and Asclepias asperula (antelope horns).³ Monarch Watch’s list for the South Central region adds A. tuberosa (butterfly weed), A. verticillata and A. viridiflora (green comet milkweed).¹⁰ Here is where the agency’s guide puts the three main ones.

Antelope horns, Asclepias asperula. “Rocky and sandy prairies; Blackland Prairie, Edwards Plateau, Grand Prairie, Rolling Plains, High Plains, and Trans Pecos Ecoregions.” In the guide’s words, it “has a distribution that includes central, north central, and west Texas.”⁹ The Wildflower Center and the Native Plant Society both list it as a monarch host.¹¹¹²

Green milkweed, Asclepias viridis. “Blackland Prairie, Grand Prairie, Coastal Prairies, glades, dry hillsides, dry pine barrens, abundant in overgrazed pastures, roadsides and disturbed ground in southeast and east Texas and west to West Crosstimbers and Edwards Plateau.” It “occurs in the eastern half of Texas.”⁹ The Xerces Society lists it plainly as “Monarch caterpillar host plant,” and the Native Plant Society as “Larval host: Monarch Butterfly.”¹³¹⁴

Zizotes, Asclepias oenotheroides. “Rocky calcareous limestone and igneous soils in the Edwards Plateau, High Plains, Rolling Plains, Trans Pecos, and Tamaulipan Ecoregions. Also, in tight sandy clay soils and dunes along the Texas coast.”⁹ The Wildflower Center calls it “a well-documented larval host for Monarch butterflies”; the Native Plant Society lists it as a monarch host.⁶¹

Put together, as far as the sources go:

• Central Texas (the Blackland Prairie and the Edwards Plateau, which Travis County straddles): all three. Antelope horns and green milkweed meet on this seam, and the guide says to tell them apart by the leaves, narrow and pointed on antelope horns, broad and blunt or shortly pointed on green milkweed.⁹ The Austin milkweed page has two sources per species.
• North Texas (Blackland Prairie, Grand Prairie, Cross Timbers): antelope horns and green milkweed.⁹
• East Texas and the coast: green milkweed, which the guide places in the Coastal Prairies and southeast Texas, and zizotes in the sandy clay along the coast.⁹ Swamp milkweed, Asclepias incarnata, is a documented host for wet ground; the Wildflower Center gives it “Moist, Wet” soil and high water.¹⁵
• West Texas (High Plains, Rolling Plains, Trans Pecos): antelope horns and zizotes.⁹
• South Texas (Tamaulipan): zizotes.⁹ Tropical milkweed is recorded as naturalized in Cameron and Hidalgo counties, which is not a reason to plant it.⁹

Butterfly weed, Asclepias tuberosa, is a host that the Wildflower Center lists as commercially available, but the Center gives it a May start to bloom and says “it takes 2-3 years before A. tuberosa produces its vibrant flowers,” and the Native Plant Society calls it “a limited monarch host plant.”¹⁶¹⁷ Grow it for summer if you like it; don’t count on it for the March pass.

The March problem, honestly

Whether fall-sown milkweed is up and green by early March is the one thing the sources don’t settle. They don’t even agree on bloom: Texas Parks and Wildlife gives April as the first bloom month for antelope horns and zizotes and March for green milkweed; the Wildflower Center and the Native Plant Society give March for antelope horns and zizotes and April for green milkweed.^9111251461 Bloom is not leaf, and no source gives a leaf-out month for any of the three anywhere in Texas. Zizotes, the Wildflower Center says, “leafs out and flowers if rains follow a dry period,” so its timing depends on the weather more than the calendar.⁶

What the record does say is that sprouts are enough. The Glen Rose eggs were on “small antelope horn milkweed sprouts” on 17 March.⁴ So the plan that fits the evidence is: seed in fall, so whatever comes up in March is already rooted; a potted native plant set out after the last freeze as a backstop; and no reliance on butterfly weed or tropical milkweed for the spring.

The coast and tropical milkweed

On the coast, where the U.S. Fish and Wildlife Service says some monarchs “remain year-round,” and where Butterflies and Moths of North America says they “may breed all year in Florida, South Texas, and southeastern California,” the planting question has a second half.¹⁸¹⁹ Tropical milkweed, Asclepias curassavica, stays green through a mild winter, and Monarch Joint Venture says that “in parts of the southern U.S. and California, the year-round persistence of tropical milkweed allows monarchs to breed throughout the winter,” which “foster[s] greater transmission” of the OE parasite.²⁰ Its instruction, if you already have it: “prune the milkweed stalks to about 6 inches in height during the fall and winter months,” “re-cut the milkweed every few weeks as leaves re-sprout,” and replace it with native milkweed “as they become available.”²⁰ The free page Is tropical milkweed bad for monarchs? has the full argument.

How we know. Sowing time and seed treatment: the Native Plant Society of Texas and the Lady Bird Johnson Wildflower Center. Where each species grows: Texas Parks and Wildlife’s Identification of Milkweeds in Texas, written with the Wildflower Center. Spring timing: Texas Parks and Wildlife, Monarch Joint Venture and Journey North’s 2025 records. We have no sourced leaf-out month, and we say so rather than guess one.