Understanding Perennial Bulbs: Types, Care & Planting

Perennial Bulbs Browse the article Perennial Bulbs

Perennial Bulbs

­­In everyday language, any plant with an underground storage organ is referred to as a bulb, even at garden centers. There are many categories, technically speaking, with different names for different structures.

­True Bulbs

­­True bulbs, such as tulips, are made of modified leaves that are attached to a flat basal plate. They surround the following season's flower bud. Some bulbs (such as daffodils and tulips) are surrounded by a papery tunic, and some (such as lilies) are covered by fleshy scales.

Corms

Corms look much like bulbs but when cut open, they have a solid starchy interior stem. Crocuses grow from corms.

­Tubers

Tubers are modified stems with starchy interiors but no basal plate or tunic. Both roots and shoots sprout from the same growth buds, called eyes. The potato is a typical tuber. Tuberous roots are similar but are actually swollen roots, not stems. Dahlias produce tuberous roots. Rhizomes are thickened underground stems. They grow in a horizontal manner, sprouting new sections as they spread. The bearded iris is a typical rhizome.

These categories of a bulb define the structure of your flowers and will determine how you eventually map your landscaping plan.

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