Last year I planted 10 root crowns in two raised beds. Each crown sent up 5 or 6 stalks, which I did not cut back. Left them alone, over the winter, other than mulching, and now, each of those 10 has sent up just one stalk. The 10 stalks are now 5 or 6 feet tall. I thought if I didn't cut them, they just produced more and more. Did I do something wrong?