We live in zone 5. We had a small parch of asparagus that produced
well, but we wanted more, so we planted a row of roots last year. All
came up, but the spears were thin, as one would expect from new plants.

Last winter was exceptionally cold. When I went out to the garden this
year, only two plants had produced small spears by the end of May; one
was the original patch, and one was from one of the new plants. This
morning the original parch has thrown up a second spear.

I'm thinking I'll wait a couple more weeks, then conclude that the
plants that have not produced are kaput.

How long should I wait before digging up the corpses and replanting.