One of the first things a gardener learns is that some plants are cultivated long before they are enjoyed. Flowering bulbs are such plants.

The group of plants known as bulbs includes many genera. While the diverse family of flowering bulbs differ botanically, they share a common feature:  A swollen underground food storage organ.

Having a bulb benefits a plant by allowing it to store starches during the growing season in order to survive periods of drought or cold. The bulb enables a plant to initiate rapid growth and flowering when favorable growing conditions return.

Making Your Selection

Spring-flowering bulbs are on sale at local nurseries in the fall. When you go to select some for your garden, you’ll notice that the bulbs vary greatly in shape and size. That’s because not all the plants in the bulb display at the nursery are true bulbs. The display probably includes corms, tubers and rhizomes, as well as bulbs. (Collectively, plants that have bulbs, corms, rhizomes or other fleshy root are called geophytes.)

True bulbs have overlapping scales, attached to a solid basal plate. Most bulbs have a “teardrop” shape, and are planted with the pointed tip facing up. Tulips, daffodils, hyacinths, Amaryllis, bluebells and most lilies are true bulbs. Some of other true bulbs you’ll find are Alliums, Fritillaries, and Galanthus (snowdrop).

Corms are condensed underground stems without the overlapping scales of the true bulb. Corms are covered with a dark brown “skin” that protects the growing tissue. Common cormous plants are gladiolus, crocus and colchicum (fall-blooming crocus). One of my favorite corms is Dracunculus vulgaris, or dragon lily. It sports a huge black, malodorous spathe-type bloom.

Tubers are fleshy, non-scaly enlarged roots or underground stems that often feature dormant buds or “eyes.” The most well-known tuber is the potato. Flowering tubers include Dahlias, Polianthes (tuberose), Anemones, Ranunculus, terrestrial orchids and some begonias. Get adventurous with an Arum, Corydalis, or a tropical Tropaeolum.

Rhizomes are not technically an underground bulb, but are fleshy, enlarged roots that reside at the soil’s surface or just slightly below it. Popular rhizomatous plants are irises, the coveted Clivia (yellow varieties are rare and can go for hundreds of dollars per plant), Kniphofia (red-hot poker plant), Schizostylis, and the lovely three-leaved Trillium.

When you go shopping for bulbs this fall, remember that you’ll find spring-blooming bulbs on sale through October. Next February, you’ll see the summer-blooming bulbs appear at the nursery. Save some room in your garden for both kinds!

Some bulbs are tropical, such as the Amaryllis you see offered at Christmastime. It is easiest to treat these bulbs as annuals, and enjoy them for just one season. If you are dedicated, though, you can cultivate them indoors and enjoy them for years.

Cultivation

Generally speaking, bulbs offer a lot of reward for just a little work. The most important considerations are planting depth and soil drainage.

Plant your bulbs, corms and tubers at two to three times the depth of the bulb itself. For example, a two-inch tall daffodil bulb should have four to six inches of soil covering it. A half-inch tall crocus corm should be covered by one-and-a-half to two inches of soil.

If you are going to err in planting depth, shallower is better than too deep. Many plants can migrate deeper in the soil, but if they are planted too deep to begin with they may not have enough stored food to send a shoot all the way to the surface.

Your best bet to ensure that your bulbs bloom and thrive in your garden is to provide them with good drainage. Few bulbs will survive in wet, heavy soils—a condition not uncommon during our rainy winter weather. If areas of your garden flood or stay soggy, don’t plant bulbs unless you construct raised beds or amend the soil thoroughly to increase drainage.

When preparing beds for planting bulbs, mix amendments that will lighten and aerate your soil. Sand and coarse grit placed at the bottom of the planting hole will help keep water from standing around the bulb. Compost will add nutrients as well as improve the texture of the soil.

Most bulbs (except for those native to woodlands) won’t appreciate an acid pH. Add bone meal and dolomite lime in the root zone to neutralize the soil. Bone meal also provides important nutrients to spring-flowering bulbs. You’ll find it in a granular form called “bulb food” right next to the bulb display at the nursery.

Don’t be rain-shy this fall—get out in the cool weather and plant some spring-flowering bulbs. Next spring, you’ll be glad that you did.