The primary bulb species used for gardens and landscapes include: true bulbs, corms, tubers, tuberous roots, rhizomes, and enlarged hypocotyls. All are "Geophytes" and, collectively, they are commonly called "Flower Bulbs". Although each specialized storage organ is morphologically different, their basic function is to serve as an organ for survival of the species. (See De Hertogh and Le Nard, 1993). In this bulletin, we refer to specific underground storage organs as corms, tubers, etc. only when citing the genus or species.

Traditional summer and fall flowering bulbs, along with selected semi-hardy and tender bulbs that can flower at various times dependng on the hardiness, climatic zone and growing procedures, greatly enhance gardens and landscapes. When they are not highly suitable for garden uses, they may, however, be readily used as container plants. Their basic characteristics and cultural requirements are summarized in Tables 1 and 2. They provide an extremely wide range of plant types, flower colors, and plant heights (Table 1), but have a wide range of plant hardiness (Table 2). Thus, all summer and fall flower are not suitable for the 10 climatic zones that exist in the U.S. and Canada.

Gardeners should be aware that some bulbs, e.g., Dahlias, Gladiolus, and Tuberous Hybrid Begonias are readily available; while others, e.g., Albuca and Curtonus, are not easy to locate and purchase. Regardless of availability, many bulbs have been included in this Bulletin in order to provide a comprehensive list.

In addition, in some climatic zones, many summer and fall flowering bulbs have the ability to perennialize, that is, flower for three or more consecutive years without being lifted. Information on these types of bulbs and their general cultural requirements is included in many books (See References). Some selected uses for these bulbs in the garden and landscape sites are:

For the latter two uses, gardeners and landscapers may desire to plant the bulbs in order to create a "Naturalized" effect.