A SECRET WEAPON FOR ARE MILKWEEDS PERENNIALS OR ANNUALS?

Many of the remaining patches of Prairie Milkweed expand in preserved patches of tall grass prairie that increase alongside railroads.I dug up alot of these very last calendar year, bur they keep popping up in all places in my flower mattress. HOW I do I get them entirely away from my flower beds?It carries a parasite of Monarch Butterflies identif