Those of us living in northern climates can enjoy many tropical or warm zone flowers in our summer gardens. But, the plants must be dug and stored inside for the winter. These tender bulbs, corms and tubers include canna lilies, tuberous dahlias, tuberous begonias, glads (gladiolus), Caladium, Amaryllis, Calla Lilies, Elephant Ear and a few others. With proper fall care and winter storage, the flowers may be enjoyed every year. If the ground freezes in your area, these flowers will not survive the winter.
Steps to Prepare Tender Bulbs for Winter
- Wait for a frost that blackens and kills back the green growth. The exception is the Hymenocallis, which should be dug before frost occurs.
- Cut the tops back to about 6 inches. This helps locate all bulbs for digging, and gives a handle to more easily lift out of the soil.
- The leaves and flower stalks can go in the compost pile, unless there were some disease or insect problems. If there were problems, dispose in the trash.
Dig the Bulbs and Tubers
- Dig carefully around the plants, using a fork or spade. Stay about 6 inches away from the roots to avoid damaging or cutting the roots.
- Lift out the clump of soil and roots, taking care not to damage the bulbs. Disease will enter easily if the skins are damaged.
- Carefully break off the large chunks of soil. It may help to rinse with a hose, leaving soil in the garden. It is fine to cut off the roots, taking care not to damage the tuber.
- If you have a selection of varieties and colors, keep them separated and labeled during this process.
Clean the Bulbs
- Dahlias and cannas should be rinsed with the hose.
- Tender corms such as glads should simply be left to dry.
- Cut off any rotted portions – will be soft and gray. Healthy bulbs are similar to a potato – firm, light colored.
- Cut the stem down close to the tuber.
Curing the Bulbs
- Dahlias, cannas, callas, caladiums and similar bulbs should be spread out to dry for 3 or 4 days, turning often. A large tarp spread in the garage or basement works well. Do not leave outside if further frosts are predicted, do not dry in the sun. If possible, dry on elevated screens for better air flow.
- Corms such as glads need to cure, which takes about 3 weeks. Turn the often during the process.
- Inspect all bulbs for insect and disease damage. Either treat with an insecticide/fungicide labeled for that plant, or toss out. Storing damaged bulbs may destroy the entire box.
Storing Bulbs for the Winter
Cardboard boxes work well, since they allow air circulation yet discourage mice invasion. All bulbs need to be stored in a cool, dry, dark place such as root cellar or basement.
- Corms such as glads can be placed in paper sacks, labeled with the color. Add some peat moss to keep the bulbs from drying out. Place the bags in a labeled cardboard box.
- Place several layers of newspaper in the bottom of the box. Large tubers such as cannas can be wrapped in newspaper and placed in a single layer. Do not crowd; leave spaces. Continue to add layers of newspaper and bulbs.
- Smaller bulbs such as begonias or callas may dry out. It is best to use peat moss. Place the bulbs on layers of newspaper, cover with peat moss, repeat layers.
- If different colors and varieties are stored, adding notes to the layers helps keep the varieties separate.
Some plants are fine left in the pots. Quit watering, cut the foliage back. Store the pots in a cool, dry location. When shoots appear in the spring or about a month before the last frost date, move the pots to a brighter light and begin watering. This method works well for calla lilies, Easter Lilies, Amaryllis and tuberous begonias, among others.
Summer Flowering Bulbs do not have to be Annuals in Northern Climates
Many summer flowering tender bulbs are sold as annuals. With some care and attention, it is not difficult to store them for the winter. Replant next spring to yield many years of enjoyment plus more plants each year!
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Valerie Prax - Valerie Prax recently retired after nearly 35 years with University of Minnesota Extension. She served as an Educator and Professor for 27 ...
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