The word “bulb” is commonly used to refer to geophytes, which are a group of plants with “underground storage organs.” There are five basic geophytes: true bulbs, corms, rhizomes, tubers, and tuberous roots. For the purpose of this article, we will focus on the more common bulb, corm, and tuber.
Bulbs, corms, and tubers are quite different than traditional seeds, and therefore must be stored and handled differently. A seed is the embryo of a plant, whereas a bulb, corm, or tuber is actually a mature plant structure. Seeds can be annuals, biennials or perennials, whereas bulbs, corms, or tubers are only perennials.
Here's a helpful guide for learning the difference between the different types of geophytes:
True bulbs can be classified into two major categories based upon their covering. Tunicate bulbs have a dry, paper-like outer covering, whereas nontunicate bulbs have a scale-like covering and are fragile while being stored or handled. True bulbs frequently create smaller offset bulbs, which can be separated into more plants. The most common types of true bulbs include daffodils, lilies, onions, and tulips.
Onions are some of the most common true bulbs.
Corms look similar to bulbs but have a fattened and flattened base of the stem. Unlike bulbs that produce offset bulbs, corms produce cormels beside the plant. Common types of corms include crocus and gladiolus.
Rhizomes tend to grow horizontally right below the surface of the soil. Because of their unusual shape, the plant has multiple growing points and can be easily propagated by cutting it into sections. Common types of rhizomes include the calla lily and the lily of the valley.
Tubers are a unique type of plant that doesn’t fit into any traditional category. They are characterized as underground growing stems that can be propagated by cutting the tuber into sections and commonly have “eyes” that will sprout to plants that grow at the surface of the soil. Common varieties of tubers include caladium, water lilies, and the unusual potato.
Unlike tubers, tuberous roots don’t have “eyes,” but they tend to sprout at one end and grow in clumps. Propagating tuberous roots is much more difficult, as you must have sufficient crown tissue in order to get a successful plant. Common examples of tuberous roots include dahlias, sweet potatoes, and tuberous begonias.
Some gardeners treat bulbs, corms, and tubers as annuals, and leave them in the ground all year long. The problem with this philosophy is that it is a waste of money to buy new bulbs each year.
Why not take a little time and effort and save some of that cash on something else for your garden instead? Storing your bulbs, corms, or tubers is the economical choice. You may even find that older bulbs produce larger plants with each passing season.
Remove bulbs, corms, or tubers from the soil before frost occurs in your area. If the bulb, corm, or tuber is exposed to harsh conditions, it could cause rot and the plant could die.
Here are some helpful tips on how to store certain types of geophytes:
Always label bulbs, corms, and tubers prior to storage. It is easy to forget what you stored and where you stored it a few months ago. Labeling the bulb, corm, or tuber with a name and even the color of the bloom, so you know what to plant where.
Some slight shriveling of geophytes is to be expected, as moisture has evaporated from the young plant. Excessive shriveling, however, may indicate a problem. Toss any geophytes that you suspect have shriveled too much.
Inspect geophytes for rot. Don’t ever try planting a bulb, corm, or tuber that is mushy or has mold on it.
© 2018 Diane Lockridge