Question
A few years ago we put flagstone in an area of our lawn that received little or no sun.  We put moss in the 1 1/2 gaps between the flagstone.  The area is watered by a sprinkling system but the moss will not fill in and a lot of it has died.  Looking for a low ground cover that will survive full shade.  I live in Salt Lake City, Utah which I believe is zone 6.

Answer
Hey, Bill.

I don't think moss is going to do well in Salt Lake under those conditions, as I think you've discovered. Even with a sprinkling system, I don't think you can keep it consistently moist so it's not going to grow and fill in like you want it to.

I will also admit that I've never used a groundcover that far north (many of my relatives live in Provo, Brigham, and southern Idaho) because you have to do patchup work each spring after the snows and freezing temperatures.

Here's three groundcovers that take shade and can tolerate dry soil during the day. I'm only including those that get no more than two inches high:

Irish moss - Arenaria verna
Foxglove - Mazus reptans
Baby's tears - Soleirolia soleirolii

What I think you really should do is find a small mom-and-pop nursery that has been in business since forever and stop by there to discuss your problem with them. I've found that the smaller nurseries that are family owned have a lot more experience in actually solving problems rather than just selling you whatever is on their shelves like Home Depot often does.

I'm also going to try to send this question to our general question pool. Maybe someone else can give you some additional answers based on their experience working in more northern climes.

If you come back to allexperts.com, you should be able to see your question in the question pool. If you don't see it there within 24 hours, then it means that I can't put it there once I've sent you an answer, so just post it again to the general area so that anyone can answer it.