North American Rock Garden Society
Canadian Chrysanthemum & Dahlia Society
GardenOntario. Website of the Ontario Hortcultural Association (OHA). Trillium, the OHA newsletter, can be downloaded from this site.
Ontario Wildflowers. This website is all about wildflowers and plants that grow in Ontario.
Heritage seeds. Some members have mentioned a difficulty in obtaining heritage seeds. This website appears to give links to several sources.