Clemson University Extension service offers over 500 horticulture guides to landscaping, ground covers, trees, garden vegetables, houseplants, and pests & diseases. Available in HTML or PDF format.
A-Z (asters to zinnias) commercial plant growing guides from Michigan State University. Includes tips on cultivars, propagation & division, transplanting, environmental impact, and harvest.
RHS plant finder database lists suppliers of over 70000 plants grown in the UK. Membership allows free access to RHS gardens in the UK and France. Gardener's references and calendar.
A school of agriculture and horticulture located in Queensland, Australia. Provides research, short courses and community services, groups and centers and news and events.
By Ohio State University, shares information on gardening and horticulture, including an international knowledge bank, plant search engine, photographs, videos, FAQs, glossary, pocket gardener, tips calendar, and an e-newsletter.