Older gardening books are valuable because they chronicle varieties long gone and methods long fallen into disuse.
This weekend I picked up the 1973 Sunset Western Garden Book (Library of Congress No. 67-15736, SBN Title No. 388) and the 1980 Ortho/Chevron All About Vegetables (ISBN 0-917102-90-8). Flipping through them, I was impressed by several things. For one, their relative dearth of scientific naming schemes (the latest editions of the Sunset book are botanically more accurate). For another, a de-emphasis of organic fertilizing and pest management, and an overemphasis on chemicals (but hey, look at who sponsored the second book). And last but not least, the plethora of older varieties of plants and seeds which have since fallen out of the seed catalogs and out of fashion. Good, I've confirmed that "Gardener's Delight" and "Sugar Lump" are, per the Ortho book, two separate varieties of cherry tomato (and not one and the same, as some people today assert). And here is the "Streamliner" strawberry that I ordered from Gurney's (the original Gurney's in Yankton, South Dakota) -- where could I find this strawberry today? Or the "Baron Solemacher" or "Alexandria" alpine strawberries once sold by Burpee (many alpine strawberries sold in nurseries today carry only a generic label)?
Every year I pick up a seed catalog and more old favorites are gone, seemingly for good. Thank God for the heirloom seed enthusiasts; without them, we'd be subjected to more and more colorful nonsense hybrid this or that every spring.
However, there was one thing I missed about these old books, other than the old varieties of seeds and plants. That was the wonderful prose. They are so much more _readable_ than equivalent later editions. It's hard for me to put my finger on why. Maybe its the wealth of complete sentences, or the flashes of humor here and there, or an overall sense of relaxation and no need to prove anything. It's gardening as enjoyment, not as ideology.
Oh, one more old book on my "to buy" list for later: "The Vegetable Garden" by MM. Vilmorin-Andrieux (Ten Speed Press, ISBN 0-89815-041-8,
1995????). It's a facsimile reprint of an 1885 book. Vilmorin-Andrieux's family had been in the seed business for some time and I believe the book is a wonderful array of varieties grown and sold at that time by their business. Some of them are names we'd still recognize.-- dkra