Polly,
I don't have a clue. I got so many that fill in I never considered groundcover. My seedlings do that for me. Start collecting your seeds and put into a hot bed or some sheltered area and see what pops up. Most of my seedlings come all sizes and from gold (some), green and blue (most) and shades in-between. Check places like the 'Hosta Farm' for the commons ones that will be the most affordable.
Stush
