I feel that if you're going to introduce mutants, completely random and unnoticed is the way to go.
Person 1 "So here is our victory garden and here are our random mutants eating my neighbour." Person 2: "How lovely! How do you get your beans so large?"
no subject
Person 1 "So here is our victory garden and here are our random mutants eating my neighbour."
Person 2: "How lovely! How do you get your beans so large?"