There is no harm in leaving the plant stalks in position, however this encourages rampant self-seeding, which is normally not desired. Really don't mulch more than the foundation crowns, as this can endorse rot. The leaves of Asclepias species really are a foodstuff resource for monarch butterfly larvae and some https://is-tropical-milkweed-a-pe12233.blogpostie.com/52815933/top-guidelines-of-is-milkweed-a-weed-or-a-flower