Best milkweed for Austin

The best milkweeds for an Austin yard are three natives: antelope horns (Asclepias asperula), green milkweed (Asclepias viridis) and zizotes (Asclepias oenotheroides). Each is a documented monarch host. Antelope horns and green milkweed grow on both kinds of ground Travis County sits on, the Blackland Prairie and the Edwards Plateau; the agency’s guide puts zizotes on the Plateau side, and the Native Plant Society also lists the Blackland Prairies for it. Monarch Joint Venture names the same three as “the most important host plants for Generation 1 monarchs in the southern US.”¹ Tropical milkweed, the one nurseries most widely stock, is the one to leave out.

Why milkweed comes first

The Xerces Society, writing with the USDA and Monarch Joint Venture: “Milkweeds are the required larval host plants for the monarch butterfly (Danaus plexippus).” And: “Female monarchs lay their eggs on milkweeds and once hatched, caterpillars feed on the plants for up to two weeks before forming chrysalises.”² No milkweed, no eggs.

Texas has plenty to choose from. Texas Parks and Wildlife’s identification guide lists 37 kinds of Asclepias recorded in the state, only one of them non-native.³ A Native Plant Society of Texas article names three of the natives for the central flyway: antelope horns, zizotes and green milkweed.⁴

Antelope horns, Asclepias asperula

Sun, rocky or sandy soil, and a deep taproot; a Texas Master Naturalist chapter notes that its “large tap roots” let it “flower even in dry years.”⁵ The Wildflower Center rates its water use medium and its soil moisture dry to moist, and says it “prefers rocky or sandy soils of prairies, pastures, plains, hillsides, brushlands, and woodlands.”⁶ The Native Plant Society lists it as a larval host for “Queen and Monarch butterflies,” blooming March to October.⁷ Texas Parks and Wildlife places it in the Blackland Prairie and Edwards Plateau, the two regions Travis County straddles.³ A 2026 study calls it “an important, yet highly toxic, host plant species to the first spring generation of monarchs in the southern USA,” and “likely the poorest host” of the three species it compared, because of its heavy latex and tough leaves; that is a reason to grow green milkweed and zizotes beside it, not a reason to skip it.⁸ It grows from seed or root cuttings.⁶⁷ Expect aphids: “Antelope-horns will inevitably have aphids,” the Wildflower Center says, and “the insects are not a problem unless the plant looks sick.”⁶

Green milkweed (green antelopehorn), Asclepias viridis

Full sun and low water, by the Wildflower Center; dry limestone soil, by the Native Plant Society.⁹¹⁰ The Xerces Society’s regional nectar guide lists it plainly as “Monarch caterpillar host plant,” and the Native Plant Society as “Larval host: Monarch Butterfly.”¹¹¹⁰ Texas Parks and Wildlife places it from the Blackland Prairie west to the Edwards Plateau.³ The Wildflower Center records it as commercially available, and gives the seed instruction: “Soak seed overnight in water. Cold moist stratification for 14-30 days enhances germination to greater than 60 percent.”⁹ Its sap is “very sticky, much resembling ‘Elmer’s glue.’”⁹

Why both of the first two. Texas Parks and Wildlife: “Asclepias asperula has a distribution that includes central, north central, and west Texas while A. viridis occurs in the eastern half of Texas.”³ Austin sits on that seam, so grow both. To tell them apart: antelope horns has long, narrow leaves that taper to a point; green milkweed has broad ones, blunt or with a short point.³

Zizotes, Asclepias oenotheroides

The one hardly anyone plants. Full sun. Texas Parks and Wildlife places it on rocky limestone and igneous soils of the Edwards Plateau and in tight sandy clay along the coast, and gives it the longest bloom of the three, April to November.³ The Wildflower Center calls it “a well-documented larval host for Monarch butterflies,” says it “loves full sun and tolerates sandy, dry soils,” and notes that it “survives periodic droughts and occasional mowing even though it has shallow roots.”¹² The Native Plant Society lists it as a monarch host.¹³ Seed gets the same soak and chill as green milkweed.¹²

One warning for the plant tag, from the Wildflower Center: its sap “causes skin irritation in humans,” “the word zizotes in this plant’s common name is a Spanish term meaning skin sores,” and “Children are most vulnerable because of their curiosity and small size.”¹² Every milkweed, this one included, carries “toxic cardiac glycosides, which can cause nausea, vomiting, diarrhea, weakness, and heart rhythm changes,” and the milky sap holds the most.¹⁴ Keep the sap out of eyes and mouths. Wash with soap and water after touching it. If sap gets in an eye, don’t rub; rinse with room-temperature water for 10 to 15 minutes and call Poison Help, 1-800-222-1222, and if pain, blurry vision or redness starts, even hours later, get an eye exam that day and say “milkweed sap,” because it gets mistaken for pink eye.¹⁴¹⁵¹⁶

Will they be up in March?

This is the one fact the sources don’t agree on. Spring monarchs arrive in early March looking for “emerging milkweeds.”¹⁷ Texas Parks and Wildlife gives April as the first bloom month for antelope horns and zizotes; the Wildflower Center and the Native Plant Society give March.^3671213 Bloom is not leaf, and a female lays on leaves: a Journey North observer at Glen Rose found nine eggs “on small antelope horn milkweed sprouts” on 17 March 2025, so sprouts are enough.¹⁸ No source gives a month when these three leaf out in Travis County. The safe plan is milkweed sown or planted the previous fall, so whatever comes up in March is already rooted; the Native Plant Society says “Fall is the best time for planting milkweed seeds.”¹³

Two milkweeds that are hosts but not spring plants

Butterfly weed, Asclepias tuberosa, is a real host and is sold commercially; Xerces lists it as “Monarch caterpillar host plant and nectar source for many bees.”¹¹ But the Native Plant Society calls it “a limited monarch host plant,” the Wildflower Center says it is “uncommon in the Hill Country,” it blooms from May, at the tail of the spring passage, and “it takes 2-3 years before A. tuberosa produces its vibrant flowers.”¹⁹²⁰ It has no milky sap, which is why it gets mistaken for something else.²⁰ Grow it for summer color if you like it. Don’t count on it for eggs in March.

Swamp milkweed, Asclepias incarnata, is a documented host, but it wants “Moist, Wet” soil and high water: a plant for an irrigated bed or a rain garden.²¹²²

A name trap. “Green milkweed” is used for two different plants. The Central Texas host is A. viridis. A. viridiflora, green comet milkweed, is a different species that blooms June to September.²³ Buy by the Latin name.

Do not plant tropical milkweed

Asclepias curassavica is the milkweed you are most likely to be sold. Monarch Joint Venture: “Tropical milkweed is attractive and easy to grow, so it tends to be the most widely available milkweed at commercial nurseries.”²⁴ It is not native to the United States; Texas Parks and Wildlife’s milkweed guide records it as naturalized only in two far-south counties and southeast Texas.³

The problem is that it stays green through a mild winter. Monarch Joint Venture, in a fact sheet whose contributors include Lincoln Brower and Karen Oberhauser: “In parts of the southern U.S. and California, the year-round persistence of tropical milkweed allows monarchs to breed throughout the winter. These year-round tropical milkweed patches foster greater transmission of the protozoan Ophryocystis elektroscirrha (OE), increasing the likelihood that monarchs become infected with the debilitating parasite.”²⁴ The numbers: “49% of winter-breeding monarchs were infected with this parasite, compared to 9% of migratory monarchs sampled in Mexico.”²⁴

The Xerces Society says it “may foster higher loads of a monarch parasite called Oe,” and recommends “planting native species of milkweeds in areas where they historically occurred.”¹¹ A 2015 article in Texas Parks and Wildlife’s Eye on Nature newsletter, by Ben Hutchins, put it this way: “Researchers have expressed concern that widespread cultivation of this admittedly beautiful plant may actually be detrimental to monarchs by increasing infection rate by a protozoan parasite, and by causing migrating monarchs to reproduce in the winter when they should be migrating. We do not recommend this plant.”²⁵ That is the article’s position, not a published agency policy; the agency’s milkweed identification guide takes no position on it.³ The Native Plant Society of Texas will not fund it at all.²⁶

If you already have it, cut it back and replace it. Monarch Joint Venture: “prune the milkweed stalks to about 6 inches in height during the fall and winter months,” and “re-cut the milkweed every few weeks as leaves re-sprout.”²⁴ Then, in its words, the plant “should be gradually replaced with native milkweeds as they become available.”²⁴ Nobody is wrong for having bought it; it is what was on the shelf.

How we know. Every species above carries two institutional sources: the Lady Bird Johnson Wildflower Center’s plant database, the Native Plant Society of Texas, Texas Parks and Wildlife’s milkweed guide and the Xerces Society’s regional nectar list. Where their bloom months differ, we print the disagreement rather than pick a side.

Where to find these plants: where to buy native milkweed in Austin. When to have them in the ground: the Austin calendar.