Australia
Tasmania, Australasian Native Orchid Society, Australia's Open Garden Scheme, Australian Gardening Clubs & Organisations, Australian Institute of Horticulture, Australian Plants Society, Australian Plants Society - Victoria, Australian Society of Plant Physiologists, Brisbane Orchid Society, Bromeliad Society, Canberra (Australia) Organic Growers Society
Canada
Bond Head and District Horticultural Society, Calgary Horticultural Society, Calgary Rose Society, Canadian Begonia Society, Canadian Iris Society, Canadian Peony Society, Communities In Bloom, East York Garden Club -- East York Ontario, Fraser Valley Herb Society, Hensall Horticultural Society
United States
California, Florida, New York, Ohio, Texas, A Cooperative Extension, African Violet Society of America, Alabama Gourd Society, Allis Gardeners Garden Club, American Association of Amateur Arborists, American Association of Botanical Gardens and Arbo, American Bamboo Society, American Bamboo Society of Southern California, American Conifer Society, American Gloxinia and Gesneriad Society
Royal New Zealand Institute of Horticulture
The mission of the RNZIH is to encourage, promote, and improve horticulture in New Zealand.
The Royal Horticultural Society
Britain's Gardening Charity, founded in 1804 to encourage the science, art, and practice of horticulture in all its branches.
The Royal Horticultural Society of Ireland
Member-led society dedicated to promoting the knowledge, skill, and practice of horticulture, arboriculture and floral art. Founded in 1816