One of the little-grown, but fabulous native milkweed species is Asclepias perennis. In the wild, this amazing plant is found from Indiana south into Texas, where it grows in seasonal flood plains, swamps, ditches, and otherwise wet areas. In the garden, however, we have found it very happy in average to moist garden soils, as you can see from the photo below. This clumping species generally grows to 20″ tall x 2′ wide. For us, the mass of flower begin in early May, and continue for months, drawing in a array of pollinators from bees to several butterflies (Monarchs, Queens, and Soldiers). Although it will take a tiny bit of shade, we find it best in full to half day sun.
I’m growing it in my bog filter which is attached to my koi pond, and it is fabulous! The pollinators, especially the little bees, etc., LOVE it!