American Association of Landscape Architects: Association homepage contains information in its mission, publications and programs
American Horticultural Society: Publications, information and resources from one of the country's oldest gardening organizations
Biodiversity Heritage Library: A collaborative effort of natural history and botanical garden libraries to digitize collections, this archive includes more than 53,000 titles that can be browsed or searched.
Horticulture Magazine Online: Gardening tips, plant information, gardening by region
International Society for Aboriculture: An excellent site for arborists, this contains information about certification, conferences and professional development, podcasts, a discussion forum, and more.
NSF Center for Integrated Pest Managment: Information concerning biological control, examples of beneficial insects, integrated pest management, and links to other websites
Nursey Crop Science: NC State page with extensive list of informational documents and links
Silvics of North America: Describes the silvical characteristics of about 200 forest tree species and varieties. Divided into 2 works: conifers and hardwoods.
Starting Your Own Nursery: Purdue University plan covers all aspects of starting your own nursery buisiness