This is Asclepias incarnata, also called swamp milkweed. It is a good choice if you don't have a lot of room for common milkweed to spread. Growing 4-5' tall, this is also a larval food plant for our monarch butterfly. Clump forming. Grows in sun or partial shade. Will grow in very wet soils but also does just fine in regular garden soil. Easy to grow. Seeds need stratification- read the packet to find out how to do this very important step!