I'm looking for a ground cover to fill the space between stepping stones. It will obviously get walked on somewhat. Also it has to come back after our MN winters. Someone told me creeping thyme would be good. Any suggestions would be great.
Well if it is like mine it is very slow growing so you would have to buy quite a bit. And mine isn't soft so make sure you have your shoes on. Other than that it should be fine as far as I know.
I find thyme rather fast growing, if given the proper conditions. It needs full sun and very well-draining soil - it will not tolerate moist soil conditions. For between pavers, I'd probably go with Elfin thyme or Thymus praecox 'Minus'. It is very low growing and quite dense in appearance with tiny, little shiny evergreen leaves. Takes foot traffic well and can be walked on easily and comfortably in bare feet......as long as not in flower and the bees not busy :-)
If you purchase in standard 4" nursery groundcover pots, you can cut each container into 4 (or more) sections, reducing the amount of material you need to purchase and creating small enough plugs to be able to fit between pavers easily. This method works well for any very low, creeping, root-as-they-grow, non-woody type of groundcover.
For a shadier situation, you could look at Mazus reptans or a creeping veronica.
I like Elfin Thyme best - it doesn't spread as far as some of the other thyme varieties, so it doesn't blanket over the stones as quickly. I found it spreads slowly it's 1st year, then fills-in quickly once it's established.
I also like Irish Moss between stones but I don't know how hardy it is in your area. The crop I have gets buried deep in snow each winter which might protect it. I was hoping to transplant some to a more exposed area, but I'm currently searching to learn if it's Black Walnut / juglone tolerant.