Association of Gardens Trusts - The web site of the umberella organization for all County Garden Trusts.
Australasian Plant Society - UK based society promoting the growing of Australian and New Zealand plants particularly in the UK and Europe, and members are welcome from all parts of the world
British Cactus & Succulent Society
British Cactus & Succulent Society - Liverpool Branch
British Pelargonium and Geranium Society - How to join and information pages.
British Streptocarpus Society - UK based Strep society, worldwide membership. Newsletter, shows, website, seedbank, advice. Join us!
Cyclamen Society - About the society and cultivation/propagation info.
Eastling Horticultural Society - Horticultural Society for the village of Eastling near Faversham in Kent
Essex NCCPG Group - The NCCPG working in Essex  for Britain's heritage of garden plants.
Gardeners' Royal Benevolent Society - A charitable organisation which has been helping disabled or retired gardeners and associated tradespersons for over 160 years. 
Hardy Plant Society - Lists of events held by the HPS and how to become a member.
HDRA - Henry Doubleday Research Organisation. Organic gardening.
Heather Society - Handy guide to heathers. Information on choosing, growing and propagating. Design your heather garden on-line.
Lakeland Horticultural Society - An educational charity with its base at Holehird Gardens in the Lake District..
Millfield Allotments Association - Club page for the Millfields Allotments Association in Faversham.
National Begonia Society - The Official wesite of The National Begonia Society. Society news & events. Tutorials and Galleries.
National Chrysanthemum Society
National Dahlia Societies - List of UK shows,societies, results, how to grow, where to buy, history of the dahlia, etc.
Newton-le-Willows Gardeners' Association - Site contains info about the Association, it's activities, and how to join.
North of England Horticultural Society - Official Website.
North West Counties Association of Allotment and Leisure Gardeners - representing allotments in Manchester, Lancashire, Merseyside and Cheshire.
Nottingham and Notts Fuchsia Society
RHS - Royal Horticultural Society web site. Link to Plant Finder (on-line version of the book with search facility).
RHS Lily Group - RHS plant society devoted to Lilies.
Scottish National Sweet Pea, Rose and Carnation Society
Soil Association - The definitive organic association in the UK.
Tatton Garden Society - Web page of the Tatton Garden Society, Knutsford, Cheshire.
The Horticulturist - The Institute of Horticulture is the authoritative organisation representing all those professionally engaged in Horticulture in the UK & Ireland.
Whittingham Gardening Club - Monthly meetings with guest speakers on all subjects of horticulture plus monthly newsletter and trips.
Woodland Trust - UK's leading conservation charity dedicated to the protection of our native woodland heritage.