Lately discovered this site, how about roses!
Roses and Antique Roses has turned mostly into a membership of warm climate gardeners. With those on the West Coast and South dominating.
I am about the only local gardener that tries to grow roses. Thus am the expert although I've only been at it here for 12 years, prior in CA. MG, Oldroser and Estevinho (Steve??) have all been helpful with advice, MG especially with seedlings. MG, Mad Gallica, I don't know if she posts here but lives in Rheinbeck. bek?
Anyway also as a Cornell Master Gardener, class of '94, I get to pretend expertise before the willing and interested at our annual Spring Gardening Day. This year I worked like a slave on a Power Point talk about roses that was well received, and I got 11 of the 22 to sign up for the Hudson River Rose Club. We'll see how many keep up their interest.
There is of course an American Rose Society in Dutchess but I hate driving and so will try to get a small group going here so we can trade plants, garden visits and experience. Anyone interested drop me an email.