Among my favourites that I use and recomend are -the Dr Hessayon 'Expert series' there are about 18 in the series at last count and are on all aspects of gardening and tell you all about the after-care etc (reasonably priced too)
The R.H.S have about 10 books in their series and are also quite good.
For one big comprehensive book - The Readers Digest 'New Encyclopedia of Garden Plants and Flowers' has it all covered too. Good Luck Tbird+