I bet if a person kept the ground around the bed tilled they would expand.

Fescue grass is a terribly competitive grass and will choke out all but the most well established plants. When I see asparagus in a road ditch or at an old farmstead it is usually spindly and hardly worth picking because of the grass competition around it. I bet if it was tilled up around it so the competition was not there so the roots could expand it would get a lot better and expand to fill the new area. We have a little in our front yard and get a picking or two a year from it, but the grass around it just keeps it held back. If we took better care of it I'm sure it would perform better.

But it is pretty easy to buy a bundle of it at the grocery store. So the incentive is just not there to put in the work.

John