Ecology and Organic Garden Organizations
Port Hope Ecology Garden (previously also Cobourg's)
Journey North
Urban Harvest - Organic Seedlings and supplies
Ontario Wildflowers - lists wildflowers
Wildflowers of Ontario - lists wildflowers
Richter's Herbs (Goodwood)
Ontario Society for Ecological Restoration
Peterborough Ecology Park
Cobourg Horticultural Society: 
Peterborough Master Gardeners and Horticultural Society
Wild About Gardening/Canadian Wildlife Federation