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.

Many ornamental 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 has included in many books (See References).  This Technical Bulletin summarizes this information for North America.  It is intended to enhance the performance of flower bulbs used in the following garden and landscape sites:

• perennial beds and in combination with daylilies, ornamental grasses, hostas, etc.
• rock gardens
• in combination with low growing ground cover plants such as ivy and junipers
• meadows
• as underplantings and border plants in combination with shrubs and trees

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

This Bulletin covers basic information required for proper planning and selection. Without question, critical planning is the key to successful gardening. It also provides specific information on flower bulbs that have the potential to perennialize with a minimum of care and maintenance.

While this information has been prepared primarily for professional gardeners and landscapers, it should be useful for all flower bulb enthusiasts and home gardeners.