Bulbs, Tubers, and Corms, Oh My!
Our springtime was awash with color this year, partly due to our bulbs providing us with blooms, as they do every year with showstopping brilliance. But spring is not the only time of year that bulbs lend a helping hand to the garden. They can provide joy in just about every season.
But what are bulbs? What types are there and what do they do? Bulbs are storage devices that sustain a plant through dormant cycles. They provide all that the plants need to grow and bloom when it’s their time to shine.
True bulbs like daffodils and tulips are entirely complete plants. They send out a stem from the bulb that produces leaves and flowers every year like clockwork. They produce bulblets at the base which are the “offspring” of the mother plant. Snowdrops are also derived from bulbs and are the first ones to show up in late winter, right before the vernal equinox. Other bulbs include alliums, onions, and amaryllis.
Tubers are underground roots with fleshy portions that store the food for the plants. Dahlias and some begonias are produced from tubers. Peonies, one of my favorites, are also considered tubers.
Corms are stout, short stems that include special tissues that store food. Some corms also produce bulblet-like babies called cormels. They can be divided from the main plant and shared with friends or in other places of the garden. Crocus and gladiolus are examples of corms.
Rhizomes are yet another type of underground stem. They grow horizontally, and in some cases, aggressively, like bamboo. However, one of our spectacular rhizomes is the bearded iris which is very manageable and spreads slowly. Other examples of rhizomes are calla lily, canna, and lily of the valley.
We enjoyed a beautiful spring with our bountiful daffodils and tulips. These are winter-hardy bulbs that are planted in autumn and then bloom in early spring. However, there are summer blooming bulbs that are planted in spring and then bloom in summer, such as dahlias, cannas, and gladiolus. They are usually treated more like annual plants or dug up and stored inside for over-wintering.
All bulbs prefer well-draining soil, and having a prepared bed rich in organic matter doesn’t hurt either. Water freshly planted bulbs so that their roots have a chance to grow and to settle the soil around them. However, they do not like saturated conditions because there is a chance for them to rot. As with everything in life, moderation is key.
I can remember as a child, the burst of yellows in the garden from all the daffodils. The splashes of reds, whites, and oranges from the tulips. We also had gladiolus, hyacinths, iris, and mom’s famous peonies. They were so beautiful. Some may have been passed down from her mother as I am told she had a green thumb as well.
As with all bulbous plants, it’s important to let them turn brown and die back naturally. Don’t cut them back too soon. Their leaves are conducting important business, photosynthesis. They are constantly making food as the sun shines down on them and storing that food in their bulbs for next year’s display.
If you’ve been paying attention, a consistent theme in my articles is sharing with your family and friends. Bulbs can be shared as well. Many of my mom’s peonies and irises are now growing in relatives’ gardens, friends’ gardens, and even in gardens down here in southern Delaware.
After three or so years in the ground, bulbs should be lifted and divided. The bulblets can be shared with loved ones or moved to open areas in the garden. They may take a couple years to produce blooms, but the wait is always worth it.
I encourage everyone to start experimenting with bulbs and plant your gardens with an array of colors, types, and bloom times. You won’t be disappointed. Have fun, and let’s garden together! ▼
Eric W. Wahl, RLA is a landscape architect at Element Design Group and president of the Delaware Native Plant Society.