I liked the stately look of the common milkweed, Asclepias syriaca which was growing in an empty lot behind our house and I also wanted to attract butterflies so I dug some up last year and planted it in several places in our yard. They all survived the transplant and are thriving... maybe too much...new shoots were coming up a foot or so beyond the main group of plants. Did I do a bad thing? Will I have trouble controlling this plant? Thanks for any comment.