Start with high-confidence perennial flowers books, then narrow by subgenre or adjacent topics.
The New England Gardener's Book of Lists
Karan Davis Cutler
Peonies
Jane Eastoe
Ranunculus
Naomi Slade
The New Hampshire Gardener's Companion
Henry Homeyer
Perennials for the Pacific Northwest
Marty Wingate
Dahlias
Tara Austen Weaver
Native Plants for Your Maine Garden
Maureen Heffernan
Ulrika Gronlund
