I don't do much on twitter besides throw up links, so I have no idea how useful a "chat" would be. But if you're into talking seeds on your computer, this, co-hosted by Chicago's own Mr. Brown Thumb, sounds interesting:
#SeedChat is a weekly discussion forum on Twitter where the participants discuss starting plants from seed, seed saving, heirloom plants grown from seed, saving and trading seeds. Twitter members can participate in #SeedChat by searching for and clicking on the #SeedChat hashtag on Twitter, or on Tweetchat, to follow along and reply to other members. #SeedChat is hosted by @xitomatl and @mrbrownthumb. There is also a dedicated Twitter account: @SeedChat that will lead the discussion every week. Join us every Wednesday at 8pmCentral/9pm Eastern to discuss seeds. Our schedule is located here.
The format for #SeedChat may be a little more structured than your average conversation on Twitter. You can submit a question ahead of time for a particular week's topic via the form below.