Garden Design Online

Timber Press has issued an impressive work on flowering shrubs –  The Timber Press Encyclopedia of Flowering Shrubs (2012), which has to be the most comprehensive volume I've ever seen. (Yes, you'll even find species and cultivars in this book that you won't find in Dirr).

Author Jim Gardiner is Director of Horticulture and Chief Curator for all of the Royal Horticultural Society in the United Kingdom, and he's put it together with US gardens particularly in mind.

For each entry, in alphabetical order by botanical name, there's a brief description of the plant, along with particular mention of outstanding characteristics, cultural requirements, and zone.

Best of all, there are beautiful photographs of every entry so that there's no mistaking what they all look like.  In the back of the book, there's a 21-page table of selected shrubs so that you can look them up by foliage and flower color, zones, size, light and soil requirements or flowering season.

In all Gardiner covers some 1700 plants with about 2000 photos.  This is definitely the book that has it all.