Bulbs are a richly varied group of plants that store their food underground. The best-known ones like tulips and daffodils are spring flowering, but these plants represent only the tip of the iceberg. Many others, like dahlias and lilies, are summer bloomers. What they all have in common is that they’re easy to grow and produce plenty of flowers. Just provide them a sunny, well-drained spot, stand back, and let them do their thing.
What are bulb plants?
A bulb is a structure that grows underground; it stores food during its dormancy and then supplies energy for an emerging plant. You know what bulbs are if you buy onions or garlic at the grocery. Good ones are dense and have some heft to them, plus a thin papery skin for protection; as bulbs age, their robustness diminishes and they dry out. They sometimes begin to sprout the beginnings of green leaves out of their tops. Gardeners also consider foods like potatoes, sweet potatoes, ginger, and water chestnuts to be bulbs.
Garden bulbs are actually much the same as the ones at the grocery. Good ones have some plumpness and density because they are full of healthy, moisture-filled plant tissue. With the right conditions, and in time, they are sure to generate leaves and the big payoff, gorgeous flowers.
Difference between true bulbs, corms, rhizomes and tubers
When you shop for garden bulbs, you may immediately notice some variations on the underground-storage theme. The minor but key differences are worth knowing because they affect not only what sort of plants the bulbs produce but also how to divide them to get more plants.
Here is a rundown of some of the plant structures that gardeners call bulbs:
True bulbs:
Bulbs are composed of concentric fleshy scales, or layers, which are actually modified leaves just like an onion. At the base of a true bulb is a basal plate, the place from which the roots grow. Interestingly, when you cut a bulb in half, you can see the future plant parts (stem, leaves and flowers).
Offsets that you can pry off and plant may appear. In some cases, notably with Lilies, you can grow new plants from individual scales.
Examples of true bulbs: Allium (flowering onion), Amaryllis, Daffodil, Hyacinth, and Tulip.
Corms:
These structures resemble true bulbs somewhat; with a growing point on top and a basal plate at the bottom. However, they don’t have the clasping modified leaves; technically, corms are swollen underground stems. Also, they use up their store of food in one growing season though new little cormels (baby corms) often appear atop the old one to carry on.
Examples of corms: Autumn Crocus, Crocus, Crocosmia, Freesia, and Gladiolus.
Rhizomes:
Rhizomes are thickened stems that grow horizontally; the roots grow down from the underside. The tip tends to have a primary growing point, though productive side-buds are common, and you can cut them off and plant the buds individually.
Examples of rhizomes: Agapanthus, Bearded Iris and many other Irises, Canna, and Lily of the valley.
Tubers:
Tubers are swollen stem bases. Roots grow from their sides as well as their bases, and you may see multiple productive buds.
The way to divide tubers varies by type. Generally, you want to cut the tuber so that each piece contains a bud.
Examples of tubers: Potato, Anemone, Tuberous Begonia, Baladium, Cyclamen, Dahlia, and Gloxinia.
Tuberous roots:
These structures are in fact roots, not modified stems. Fibrous roots, like fingers, radiate outward from a central point. You can easily divide these roots to get more plants, making sure, of course, that each piece has at least one bud on it.
Examples of tuberous roots: Alstroemeria, Clivia, Eremurus, and Ranunculus.
Many gardeners discuss the differences between hardy bulbs and tender bulbs. Unfortunately, making the distinction isn’t easy, because a tender bulb in one climate (like Zone 4) may be a hardy one in Zone 7.
Generally, hardy bulbs can survive wintering in the ground without too much trouble, whereas tender bulbs have to be dug up and stored. Your local nursery can help you determine which bulbs are considered hardy in your area.
Early and late blooming bulbs
Many bulbs bloom in springtime; those bulbs are the most familiar and beloved to gardeners in cold winter climates. However, fewer but no less pretty ones make their show in summer or even fall.
The terms early, mid-season, and late abound in bulb descriptions. This entire naming system means is that some bulbs burst forth earlier rather than later all during the springtime.
A month or more of time can separate the first snowdrop from the first tulip or the first tulip from the last tulip.
The expected blooming time is worth knowing so you can plan for continuous color or set up nice color duos or spectacular full-bed shows. The reason people plant most spring-blooming bulbs in the fall is not just so the plants can get a head start on root growth. These bulbs also need a period of cold (so obligingly supplied by a winter in the ground) to maintain their biological clocks.
The warmer, thawed-out but moist soil of spring, not to mention the warm sun above, coaxes them at last to burst into their full and glorious potential. In mild-winter regions, gardeners can buy some bulbs pre-chilled (these plants have a limited selection compared to all the spring bloomers), or gardeners can refrigerate regular bulbs for a specified period (at least eight weeks) and then plant them in late winter or early spring.
Become familiar with the most popular bulbs
You can find many different types of bulbs, but they all have one thing in common: They are packages of life just waiting to be planted. They differ from seeds in that they contain within them the beginnings of leaves, stems, and flowers. All they need is to be planted and watered, and the growth process can begin.
The common spring-flowering bulbs include tulips, noted for their impressive range of flower types and colors; daffodils, some of the most rugged and easiest to grow of all bulbs; and lilies, which, by planting different varieties, you can have blooming from late spring to early fall.
