There are many elements to the landscaping at the Williamsville home of Susan Holt: a long stone wall, a winding gravel path leading to a secluded shade garden, a waterfall as the focal point of a lush back yard. The vegetation is full, abundant, interesting and colorful. What you won’t see is many flowers. Some of the few blooms are on the flowering dogwood, the white flowers on the bush in the first photo. “I intentionally have a foliage garden,”…