Marking the asparagus crowns with the little flags is a great idea! When I lived in Germany the neighbors covered their asparagus with cardboard to cause the spears spears to turn white ,it was considered a delicacy…..they lifted the cardboard every few days to check.
Look up Indian Runner Ducks. They don’t swim, or fly, and they love to eat weeds, slugs, and snails. Oh, and caterpillars. Many permies swear by them…. Cheers, Rov