Flowering this week is our 2019 seed collection from Texas of the Evening Primrose looking Milkweed, Asclepias oenotheroides. This odd clumping milkweed, which tops out at 18″ tall, only grows natively from Louisiana west to Arizona, and south into Mexico in very dry sites. Hardiness is most likely Zone 7b-10b.
As gardeners around the country are encouraged to plant more asclepias to encourage monarch butterflies, many folks are finding out that not all species of asclepias make good garden plants. As a genus, asclepias consists of running and clump forming species. There are number of horribly weedy garden plants like Asclepias speciosa, Asclepias syriaca, and Asclepias fasicularis. These plants are fine in a prairie garden, but are disastrous in more controlled home gardens.
One of our favorite clumping species is the easy-to-grow, Arizona-native Asclepias angustifolia ‘Sonoita’. This superb species was shared by plantsman Patrick McMillan. It has proven to be an amazing garden specimen, thriving for years, despite our heat and humidity. Did I mention it flowers from spring through summer?
One of the little-known native asclepias, milkweed, is flowering in the garden this week. Asclepias variegata, redwing milkweed, is a widespread native, ranging from Canada and Virginia south to Florida, and west to Texas. So, why is this virtually unavailable commercially? Our plants typically range from 1.5′ to 2′ tall, although 3′ is possible. For us, it performs best in part sun to light shade.
The specific epithet “variegata” which refers to two colors on the flower was certainly a poor choice, since most asclepias have multi-color flowers. Of course, Linnaeus didn’t have the benefit of the internet back in 1753.
We’ve been experimenting to see how many species of asclepias will survive in our climate, and one that has been quite fascinating is Asclepias subulata. This odd species from the southwest deserts of the US has evergreen glaucous stems, and not much in the way of leaves. It will be quite interesting to see what the butterfly larvae actually consume. It did flower for us this fall for the first time. This will be our first winter, so fingers crossed it can take our cold and wet temperatures. We sited this on a slope in one of our crevice gardens, so it wouldn’t drown in our summer rains.