- American Rhododendron Society
- Bees are Life
- Canadian African Violet Society
- Canadian Iris Society
- Canadian Peony Society
- Canadian Rose Society
- Cobourg Ecology Garden
- Cramahe Horticultural Society
- Dry Stone Walling Across Canada
- Grafton Horticultural Society
- International Clematis Society
- Master Gardeners of Ontario
- Northumberland Master Gardeners
- Ontario Association of Landscape Architects
- Ontario Daylily Society
- Ontario Delphinium Club
- Ontario Horticultural Societies
- Ontario Regional Lily Society
- Ontario Rock Gardening Society
- Ontario Water Gardening Society
- Orchid Society of the Royal Botanical Gardens
- Peterborough Master Gardeners
- Port Hope Horticultural Society
- Royal Horticultural Society
- Seeds of Diversity
- Sustain Ontario
- Tallgrass Ontario