YARD AND GARDEN: Bulbs, corms, tubers, roots and such | Home & Garden

Master Gardener Rita Wiessing expounds on bulbs and such.

With fall quickly approaching, you may have begun receiving nursery catalogs featuring a wide variety of bulbs and other rooting structures. Like many other items from cars and trucks to lumber and building materials, bulbs may be in short supply this fall due to problems with labor, transportation and other COVID-related issues.

So, if you see bulbs and roots that are available in varieties you like, you should probably buy them before the supply is gone. If you are ordering from catalogs, remember that waiting too long will limit your choices.

Bulb is a general term that most people use to refer to underground storage structures of plants that can be used to grow new plants. But don’t be surprised when more scientific descriptions use terms such as “true bulbs”, tunicate bulbs, imbricate bulbs, corms, tubers, tuberous roots, rhizomes, and fleshy roots.


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There are significant differences among these from a botanical standpoint but each is an underground storage structure that can be used to grow some of our most popular and beautiful garden plants. Depending on the variety, they can provide blooms from early spring, such as snow drops and winter aconites, to late fall, with dahlias and cannas. Winter hardy bulbs are usually planted in the fall and do not need to be dug annually. Tender bulbs are generally planted in the spring and must be dug and stored over the winter.

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Daffodils, tulips and crocus are some of the most popular winter hardy bulbs. Daffodils may also be referred to as narcissus or jonquils. These terms are confusing but all are members of the genus narcissus which is their Latin or botanical name. Daffodils and jonquils are local names brought to us by different groups of English colonists. Whatever you call them, select tulip and daffodil bulbs that are firm, free from evidence of disease, and remember that size makes a difference.


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Size may vary from one inch up to three or slightly more inches in diameter. A small bulb will produce smaller blooms and fewer of them. A one inch bulb will most often produce a single small flower whereas a three inch one may produce three or more larger blooms. Once you have obtained your bulbs, plant them immediately or keep them in a cool place until planted.

Daffodils and tulips prefer soil with good drainage and high organic matter. Their light requirements vary depending on whether they are early or late blooming. Fertilizing the bulbs when planting will help them establish for spring blooming. Fertilizing again in the spring just as the leaves emerge will keep the bulbs healthy and provide nutrients needed for flowering.

As a general rule of thumb, daffodils, tulips, and crocus should be planted two to three times as deep as the bulb is tall. So if the bulb is two inches tall, the bottom of the hole in which it is planted should be four to six inches deep. After the blooms are finished, remove the bloom stalk but do not remove the foliage. The leaves will continue to nourish the bulbs and after four to six weeks will dry on their own.

Other varieties of winter hardy bulbs include scilla, snowflakes, grape hyacinths, camassia, foxtail lilies, alliums, and varieties of Asiatic and oriental lilies. All are available for purchase in the fall.

Tender bulbs are those that cannot withstand winter cold in our zone. These are planted in the spring after the last frost and are dug and stored over the winter months. These include calla lilies, cannas, dahlias, gladiolus, oxalis, tuberose, and elephant ears among others.

These are usually not available for purchase until spring. Just as with the winter hardy bulbs it is important to plant at the correct depth but there is no easy guide for that as there is with tulips and daffodils. Many require full sun but some such as oxalis and elephant ears are quite shade tolerant.

Probably the most difficult task in growing tender bulbs is knowing when and how to store them. Generally we receive a frost in October and if you are uncertain which bulbs need to be dug before freezing it is best to consult a reliable source.

Most tender bulbs are air dried (cured) for several days before storing and then stored in vermiculite or peat at temperatures ranging from 40-50F. Our homes are usually too warm to store them well and they may rot or dry out. Even basements in modern homes are too warm. Garages may work but it is good to know the temperature if you try this.

Also tender bulbs may require a small amount of moisture in the winter. This whole process may be a bit tricky so some gardeners treat them as annuals. I would suggest a second choice. Try storing them in different areas and see where you get the best results. It may be a crawl space under your house, a corner of your garage, or even an old cooler in your basement.

Consider all the bulbs, corms, tubers and roots you see in the stores or in your catalogs and try something you’ve never grown. It may become your new favorite plant.