Let's Go Gardening

General gardening site, with versions geared towards US and UK gardeners. Tips and articles, informational resources, links to events, societies, and public gardens, and a forum.
http://www.letsgogardening.co.uk/

Yardener.com

Lawn and garden resources for homeowners whose garden is not their hobby. Includes information and care data for many plants, shrubs, and trees, and dealing with pests and problems.
http://www.yardener.com/

Hort.net

Offers a collection of garden reference materials, including a plant gallery and profiles, archives of mailing lists, gardening news, and links.
http://www.hort.net/

MyGardenGuide

Offers plant database with photos and summary information, Q&A on various garden topics, and a garden blog.
http://www.mygardenguide.com/

Garden Terms

Gardening dictionary with brief definitions of a large number of terms, optionally arranged by category.
http://www.gardenterms.com/

Garden Ideas

Articles and advice on a variety of gardening topics.
http://www.gardenideas.com/

LoveToKnow Garden

Short informational articles on gardening topics, vegetables, and ornamental plants, contributed and edited by users.
http://garden.lovetoknow.com

Contemporary Patio Ideas & Patio Decorating

Information and Resources on Contemporary Patio Decorating & Ideas. You will discover ideas and tips that you never knew before that will transform your patio into personal sanctuary.
http://www.aboutpatiodesigns.com/