Small-Space Gardening : There's no end to the advantages of gardening in containers, and gardening expert Peter Loewer's new book on the subject provides the perfect introduction. Containers, of course, are the norm in cities and many suburbs, where space is at a premium, but gardeners with plenty of room will also appreciate the benefits of container planting. Containers dress up front walks and mailboxes, hang brightly from the limbs of trees, and energize a deck with color and life. They are a great laboratory for "experiments," and also allow a gardener to grow plants that wouldn't otherwise winter over in northerly climate zones. Older gardeners also love container gardening for its relative simplicity and ease of maintenance.