San Antonio and Austin, Texas — Fall is the time to plant wildflowers, including milkweed, the Monarch butterfly host plant.  As Monarch Watch announced its Bring Back the Monarchs milkweed restoration campaign last week, questions have appeared in our emailbox regarding which species are best for San Antonio and Austin yards, ranches, or even a vacant lots that beg for a butterfly garden.   The following Milkweed Guide aims to point you in the right direction.

Antelope Horns

Antelope Horns, photo courtesy of Monarch Watch

For wildscapes, ranches, and large plantings in our area, Dr. Chip Taylor of Monarch Watch suggests native species such as Antelope Horn, Asclepias Asperula, and Green Milkweed, Asclepias viridis--sometimes called Green Antelope Horn Milkweed.  These species are especially appropriate to Austin, San Antonio and the Hill Country.  They both bloom a greenish white in summer and fall, and sport an intriguing, waxy bloom.
Dr. Taylor also recommended Zizotes Milkweed, Asclepias oenotheroides, which is appropriate for South and West Texas.
Like many of the Bring Back the Monarch recommended milkweed, Zizotes Milkweed seed is not commercially available says the highly knowledgeable Kip Kiphart, a milkweed specialist who volunteers at the Monarch Larvae Monitoring Project at the Cibolo Nature Center in Boerne.  Kiphart knows his milkweed and trains dozens of volunteers annually on planting, harvesting seeds, and monitoring the egg-laying and caterpillar hatching of Monarch butterflies.

Monarch on Swamp Milkweed on the Llano River

Another excellent native milkweed for our area is Swamp MilkweedAsclepias incarnata. This one only grows along rivers and streams and is an excellent choice for riverbanks in the Hill Country.  It blooms pink and provides hosting and nectar in the Fall.
For your home garden, both Dr. Taylor and Kiphart suggest the Antelope Horns above or Tropical Milkweed, Asclepias curassavica. The latter is widely available at garden centers and germinates easily from seed.  Its buxom yellow and orange blooms are a favorite of many butterflies.
Native plant purists begrudge its popularity because Tropical Milkweed is “nonnative,” but Dr. Taylor takes a more pragmatic approach.  Tropical Milkweed is easy to maintain in a garden or greenhouse and provides reliable hosting and nectar.  “Tropical Milkweed is the species on which Monarchs evolved.  They’re basically a tropical species following their host plants,”  he says. A recent study also suggests that the toxins in Tropical Milkweed innoculate Monarch moms and their young.
Finally, another choice for home gardeners is Butterfly Weed, Asclepias tuberosa. Kiphart asserts (and I agree with him) that this plant is commonly mislabeled at nurseries.  One of the best ways to tell if a milkweed in question is tuberosa is to break off a leaf and see if  milky latex pours out.  If it doesn’t, then it’s Butterfly Weed.
Detractors of Butterfly Weed point out that it doesn’t contain the toxic cardenolides that protect the Monarch from predators, thus should be avoided.  Kiphart notes that the plant’s gorgeous orange blooms provide ready nectar for Monarchs and other pollinators in the Fall, when nectar sources are wanting.
While it can be challenging to find plants in the Fall, you can order seeds or harvest them yourself from fellow gardeners.   Milkweed seedpods are busting open as we speak. Check with local nurseries.  In San Antonio, we like Schulz Nursery, Millberger’s and Fanick’s.    In Austin, Barton Springs Nursery has a fabulous collection of native plants.  Our favorite source for native seeds is American Native Seed in Junction, Texas.