Even though Verbena bonariensis isn't native to the southeast, adult monarchs love it. But milkweed is the only food source for monarch caterpillars.
Orange milkweed (asclepias tuberosa) is easy to grow in dry, sunny, well drained spots. You can also grow it in a pot since it only reaches about 18" high. All pollinators love it. Whorled milkweed (asclepias verticillata) is another excellent choice for dry, sunny spots.
My garden is full of native plants but it's also full of hybrids and cultivars. 'John Fanick' phlox was moved next to euphorbia corollata last fall while spigelia marylandica thrives next to a hosta whose name I forgot. But when a nonnative plant is introduced to the garden, it must conform to the ethos of "Do no harm". It must support the ecosystem within the garden and cater to the needs of local pollinators. If it doesn't attract wildlife, it needs to be a problem solver like the epimediums that laugh off dry shade and rarely require extra water.
Southeastern native spigelia marylandica brightens a partially shady corner.
But sometimes we are innocently duped and add plants that not only harm our local pollinators but are contributing to their decline. Tropical milkweed, asclepias currassavica, has been shown to alter the migrating behavior of monarch butterflies, leading to fatal infections of OE (Ophyryocystis elektroscirrha), a parasite that eventually kills monarch and queen butterflies. Instead of migrating to Mexico after they've laid their eggs on native milkweed, they stay and overwinter in warm areas where tropical milkweed is plentiful in home gardens.
Monarch caterpillar on orange milkweed.
Cheap and readily available, tropical milkweed blooms long after the natives have gone to seed. In our eagerness to help our beloved monarchs we've actually done more harm than good. After reading an excellent post on Southern Meadows describing the disastrous affects of tropical milkweed on monarchs, I quit growing it and began filling my garden with native orange milkweed and swamp milkweed.
Pink swamp milkweed (asclepias incarnata) is much taller than orange milkweed and likes moist, rich soil.
But all is not lost. While clean, pesticide-free milkweed may be a challenge to find locally, it's easy to find online. The following nurseries carry many varieties of milkweed that have never been treated with pesticides. Many are available as seed as well as plants.
Annie's Annuals - CA
Bluestone Perennials - OH
Dancing Oaks - OR
Digging Dog - CA
Far Reaches Farm - WA
Forest Farm - OR
Joy Creek Nursery - OR
Niche Gardens - NC
Prairie Moon Nursery - MN
Prairie Nursery - WI
Tripple Brook Farm - MA
Xera Plants - OR
(Asclepias does well when winter sown. See my Winter Sowing page to learn how.)