GardenHere
   Internet community and forum for trading landscape plants. Also some articles on garden and plant tips.
   http://www.gardenhere.com/

Gardenpassion
   Seed trade site with searchable lists of varieties offered and sought, as well as tips on identification, seed collection, and storage.
   http://www.gardenpassion.net/

Gardenweb: Exchanges & Trading
   Members post their offerings and wants on the forums (various plant and seed categories), and can also maintain exchange lists in their member profile.
   http://forums.gardenweb.com/forums/exchind/

Plant Internet Directory
   Allows the Australian public to list plants for sale and review listings from other gardeners.
   http://www.plant.id.au/

Plant-Traders
   Online community of people sharing, swapping and selling plants, seeds, bulbs, and cuttings.
   http://www.plant-traders.co.uk/

SeedSwappers.com
   Free site for seed trading and swapping by seed swapper enthusiasts. Also has hints and tips on home gardening.
   http://www.seedswappers.com/

World Plant Exchange
   Offers free offers and requests for plant and seed traders worldwide.
   http://www.worldplantexchange.com/