This is a good website for perennial gardening: http://www.perennialresource.com/
An attractive site, but pretty restricted to it's region,
the upper Midwest: check the listings for botanical and
public gardens. Also, the perennial reading list is com-
pletely unbalanced - have to wonder if the books on there
were paid submissions. . .
Oh, I am sure they are paying somehow -- either directly for the listing or by sponsoring ads on the site.