American Horticultural Society  
   The AHS mission is to educate and inspire people to become successful and environmentally responsible gardeners by advancing the art and science of horticulture.
   http://www.ahs.org/

The Royal Horticultural Society  
   Britain's Gardening Charity, founded in 1804 to encourage the science, art, and practice of horticulture in all its branches.
   http://www.rhs.org.uk/

Hensall Horticultural Society  
   Dedicated to the ideal that a horticulturist likes to share, create beauty, has pride in the community, and is concerned with the environment.
   http://www.angelfire.com/on/hensallhort/

Massachusetts Horticultural Society  
   Information about the society and horticulture. Marketplace schedule.
   http://www.masshort.org/

Calgary Horticultural Society  
   Information concerning gardening and the unique climate and growing conditions of Calgary.
   http://www.calhort.org/

Northern Plains Botanic Garden Society  
   Working to establish a botanic garden, conservatory, and arboretum in the Fargo, North Dakota and Moorhead, Minnesota area.
   http://npbgs.tripod.com

The Geraniaceae Group  
   An international horticultural club interested in the species of all the genera of the Geraniaceae Family.
   http://www.geocities.com/RainForest/Canopy/3139/

Launceston Horticultural Society  
   Provides information and contact details about the society.
   http://www.tased.edu.au/tasonline/launhort/

New Ornamentals Society  
   Devoted to the study of new and rare ornamental landscape plants. Includes an online source guide and plant encyclopedia.
   http://members.tripod.com/~Hatch_L/nos.html

The Ecological Landscaping Association (ELA)  
   Advocating environmentally responsible landscaping and horticultural practices by professionals and the public.
   http://www.ELA-ecolandscapingassn.org

MSU Cares  
   Information provided by the Mississippi State University Extension Service and the Mississippi Agricultural and Forestry Experiment Station.
   http://msucares.com

Southern Nursery Association  
   This 100+ year-old trade association has assembled a great resource for horticulture in the 16 southeastern states of the U.S. It includes interactive searches of current members or exhibitors and their products, and over 5,000 pages of horticultural rese
   http://www.sna.org/

Northern Gardener  
   Home to Northern Gardener Magazine and the Minnesota State Horticultural Society. Features gardening articles, advice, tips, calendar, and resources.
   http://www.northerngardener.org/

Virginia Nursery & Landscape Association  
   State trade association for nurseries, garden centers, landscape contractors, landscape designers,growers, interiorscapers, greenhouses working for the common good of the nursery industry in Virginia.
   http://www.vnla.org

Parkhill Area Horticultural Society  
   Open to amateur and professional gardeners.
   http://www.yfhconsulting.com/horticultural/default.htm

Hardy Plant Society of Oregon  
   A non-profit volunteer organization for beginning, experienced, amateur, and professional gardeners.
   http://www.hardyplantsociety.org/

Royal New Zealand Institute of Horticulture  
   The mission of the RNZIH is to encourage, promote, and improve horticulture in New Zealand.
   http://www.rnzih.org.nz/

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
   http://www.rhsi.ie

San Diego Horticultural Society  
   Promoting the enjoyment, art, knowledge and public awareness of horticulture in the San Diego.
   http://www.sdhortsoc.org/

The Pennsylvania Horticultural Society  
   The Society provides a place where all greening enthusiasts can pursue their own particular horticultural interests. Founded in 1827.
   http://www.pennsylvaniahorticulturalsociety.org/

International Crabapple Society  
   Identifies disease-resistant cultivars for nursery and landscape professionals, as well as the gardening public.
   http://www.malus.net/

Virginia Green Industry Council, Inc.  
   Unifying horticulture in Virginia.
   http://www.virginiagreen.org/

Horticultural Society of Maryland  
   Providing education for all people in the field of horticultural arts and sciences.
   http://www.horticulturemd.org/

The Mediterranean Garden Society  
   Resources for gardeners in the Mediterranean basin and similar climate regions.
   http://www.themediterraneangarden.org/

Australian Institute of Horticulture  
   A professional association for qualified Horticulturists in Australia, including Landscape designers, educators, writers, and nursery people.
   http://www.aih.org.au/

Scottish National Sweet Pea Rose & Carnation Society  
   Society home page with Sweet Pea & Rose trial results, flower show venue & reports.
   HTTP://WWW.SNSPRCS.ORG.UK

Ontario Horticultural Association  
   Provides information, organization and networks for Ontario gardeners.
   http://www.gardenontario.org