From Carol Eichler:
In completing my request for the NARGS seedlist, I came across a great resource - Gardens North, a nursery out of Ottawa, Ontario that sells seeds. Their website (http://gardensnorth.com) is a great resource in that you can look up plants from their on-line catalog. Under the "perennials" category for instance you can look up a plant to see a picture and description plus information about germination and hardiness. Even though this is a Canadian nursery they use USDA Hardiness Zones, hooray! There's even one section on seeds from Ruksans' nursery (not extensive, but presumably Gardens North has done their research on hardiness).
Perhaps I should explain how I "came across" this nursery. As part of my selection of seeds from the NARGS seed exchange, I was using the Google Images search engine to look up plant pictures and other information. By clicking on a particular image I also got the link to the "parent" webpage. To the extent that I allowed myself these side excursions, Gardens North wasn't the only great find. Among others I found a great tourist agency out of the UK that offers wonderful accommodations and tours to the dolomites in Northern Italy. I've been dreaming about a trip there ever since Harry Jans' talks. :)