Rodale's illustrated encyclopedia of perennials Book

Can't remember when to divide your irises? Having trouble with your clematis? This is one of the first places I turn to research garden perennials. After two preliminary chapters on garden design and growing perennials, the bulk of the book consists of an alphabetic listing of hundreds of perennials, each entry with a photo, pronunciation guide, description, and tips on how to grow the plant and its uses in landscaping.

The book is written in a marvelously clear and unpretentious manner. Opening it at random, here's part of the entry for Lamiastrum (lay-me-AS-strum): "Plant in average to rich well-drained soil in partial to full shade. In northern zones, plants tolerate some direct sun. Divide clumps as they spread out of bounds, or pull plants from places where they don't belong. Take tip cuttings in spring or summer."

And that's really all you need to know, isn't it?