There are lots of 'Encyclopedia of perennials' type of books out there; you can generally find them on sale at Borders or Barnes and Noble.

But in its general usefulness, nothing beats 'The Well Tended Perennial Garden' by Tracy DiSabato-Aust. I also enjoy books by William Cullina (on native plants), and Michael Dirr has of course written the authoritative book(s) on trees and shrubs.

Agree with 'The Well Tended Perennial Garden' and add 'Time Tested Plants' by Pamela Harper. She is in VA Beach area, so it works well for our area as well.

I have alot of gardening books, but my absolute favorite & one I refer to all the time is The Southern Gardener's Book of Lists by Lois Trigg Chaplin (Taylor, 1994). No pictures, just great lists of plants that work well in my area, with little sidebars & notes from experienced gardeners. I also try to get all the new gardening books from the library & I subscribe to Garden Design magazine & work p/t in a garden center-I get garden ideas from all over, but this book is indispensable to me!

The one book (and I have many, many gardening books) that I return to again and again is Taylor's Master Guide to Landscaping by Rita Buchanan. It's all in there.

Graham Stuart Thomas is a well-known English author who wrote an excellent two volume reference, buttressed by additional books on roses, groundcovers, etc. Not a first pick, because of the English author and the lack of illustrations, but the two-volume set is fairly all-inclusive, so that when you finally have something you can look it up and know what you have. If you see them on sale anywhere they are worth picking up.

For shrubs, I agree that Dirr is the man. Ignore him at your peril, but if you have his book, at least you will have been warned. I took him with a grain of salt regarding the eventual height of Allegheny viburnums, but he was absolutely right. He was right about pruning, too.

I have an older set of two reference books on flowers that I especially love because it gives an excellent hand-drawn illustration of each, a good description of habitat, and a history of where each plant was first discovered, but it is temporarily packed away and I can't remember the name...maybe someone else will know. It may be out of print, but it should not be if it is.