"F Murtz" wrote..

Do potatoes keep growing after greenery dies off?

No they don't but they are still alive so they do change depending on
storing conditions. What does happen as the hulms die down is they they
develop thicker skins which is better for storage but there is no benefit in
leaving them in the ground longer, quite the opposite is you have a slug
problem.
--
Regards. Bob Hobden.
Posted to this Newsgroup from the W of London, UK