I have found that local arboretums and botanic gardens have the best help for horticulture or garden history.

I think you can get this sight it lists several books at one arboretum. I am showing as an example of what they have available in their libraries

http://members.aol.com/arbexhibit/NAMBOT2.htm

Here are some links to check out.

history of horticulture

http://www.hort.purdue.edu/newcrop/history/default.html

a timeline

http://www.gardendigest.com/timetab.htm

I have a list of interesting books as well,one such...

'Gardens of the Colony and State Gardens and Gardeners of the American Colonies and of the Republic before 1840'
Alice B Lockwood

Thank you!

John ~

Three books by Ann Leighton should be a good start: Early American Gardens--"For Meate (sic) or Medicine"; American Gardens in the Eighteenth Century--"For Use or for Delight"; and American Gardens of the Nineteenth Century--"For Comfort and Affluence." Incredible scholarship, yet easy to read and interesting. I bought mine in 1989 and still like to go back to refer to them often. They may be in your library. Good luck!

BG:
Thanks! Amazon.com has several and I'm going to order them.

Dear BG:
Thanks again! The three Ann Leighton books you recommended just came in the mail. They look good -- but now I'll have to find the time to read them.