In a Southern Garden: Twelve Months of Plants and Observations by Carol Bishop Hipps
Organized month by month, the author (who is based in Huntsville, AL) gives details of plants that you would see in that month. There are some recommendations and a lot of cultivar information. The book is easy and entertaining to read. You don't have to be a fanatical gardener, but of course it helps. There is also an occasional amusing quip. I particularly liked the story where the author asked Allen Bush of Holbrook Farm and Nursery if he knew of any named cultivars of Chrysogonum (Green and Gold), only to discover later the existence of C. virginianum "Allen Bush".