Nursery and Garden Center List

I'm looking for a listing of garden centers and nurseries across the US, Canada and UK, preferably in an Excel spreadsheet or csv export from a database. I've contacted several professional organizations, and they want to charge. I understand costs for printing a document, but this is digital via email.
I know some of you would disagree, but I would think that they would jump at a chance to get their members out to potential customers. I'm using it for the designers who work from to source plants for projects. It will also be available via the iPhone version of the site with the ability to map and call vendors directly.
As with the other projects I've requested information about, I'm more than willing to share the compiled information with anyone who sends me information.

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