Garden columnist and owner of a landscape design business, Marianne Binetti has been searching for the perfect plant--impossible to kill, but always in full bloom. It's something most gardeners are probably looking for, not to mention an honest request coming from the author of the Storey titles, Shortcuts for Accenting Your Garden and Tips for Carefree Landscape. Mother of three, Marianne's articles have been featured in Woman's Day magazine, and she writes a syndicated gardening column called "The Compleat Home Gardener" which runs in more than 20 newspapers in Western Washington, where she