I've always wondered if the moss milkshake was an urban legend...apparently not.
Q: What's a moss milkshake? Is it hard to grow moss as a ground cover?
A: Not if you have shade and acidic soil, as gardeners trying to grow lawn know all too well. Moss milkshakes encourage moss to grow, but they only work if you apply them in shady, somewhat damp conditions. Put a handful of moss (from the garden or nursery) into a blender. Add 1/2 teaspoon of sugar, a can of beer OR a cup of buttermilk (either beer or buttermilk works fine). Blend until the moss is mixed with the liquid, then spread it over rocks and the ground where you want the moss to grow.
For a supremely mossy experience, visit the primeval-feeling moss garden at Bloedel Reserve on Bainbridge Island (www.bloedelreserve.org). To see how moss can be used to great garden effect, visit the Japanese Garden in Washington Park Arboretum (www.seattle.gov/parks/parkspaces/japanesegarden.htm).