This cultivar of unidentified parentage was originated by Carl Mack and registered on his behalf by Peter and Jean Ruh of Ohio in 2002. It is a large size plant which grows about 19 inches high with a spread of around 38 inches. The leaves are green, have a heart shaped base and are slightly rippled. In July, it bears pale lavender flowers that do not set seeds.

'Fox Lake' may have been sold as 'Mackwoods No. 18'.