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Fall Care for Tender Perennials/Bulbs
by Sarah Browning, UNL Extension Educator
Many tropical or sub-tropical plants are popular additions to Nebraska gardens. They provide great color with their showy flowers and leaves, and also interesting foliage. But since these plants cannot survive a Nebraska winter, even as dormant bulbs in the soil, it’s important to dig them in fall and store them properly so that you can replant them next spring.
One benefit of digging up and storing bulbs, rhizomes or tubers in the fall, is that you can save money in your plant budget next year. Plus, rhizomes and tubers can often be divided into several sections, enabling you to create several plants from one.
Common plants that fall into this category include Canna, Caladium, Alocasia and Colocasia (both often commonly known as elephant ears), Gladiola, Dahlia, and Zantedeschia (calla lily). Ornamental sweet potato tubers can also be treated as a tender bulb, by harvesting them in the fall and replanting the following year.
If you haven’t dug your tender plants yet, it’s time now to get that done. Anytime after the foliage has died back, usually after a couple light frosts, it’s OK to dig up the roots. Be careful when digging not to damage the roots. Gently loosen the soil around the roots with a garden fork or spade, starting 10-12 inches or more away from the plant stem to avoid cutting the roots. Once the soil is loose, use the dead foliage to lift plants out of the ground.
Brush as much loose soil away from the root structures as possible. It’s usually better not to wash the roots. Allow the bulbs or roots to cure at temperatures of 60-70 F degrees, away from strong wind or direct sunlight, for about 1-3 days before placing them in storage.
In the case of gladiola, dig up the old corm and new growth together, and allow them to cure for about three weeks. Then remove the old corm from the base of the new growth, and place the new corms in storage. Very small cormels can be saved, but it will be several years before they reach blooming size.
Store and label each group of plants to keep colors and cultivars together; one easy way is to store small bulbs or roots in labeled paper bags. Choose a cool (50-55 F degree), dark location for storage. Canna, caladium, calla lilies, and dahlias do best if stored in vermiculite or peat moss that has been slightly moistened.
Be sure to check periodically during winter for soft rotting roots, or excessive drying. If rhizomatous or tuberous plants, such as canna, dahlia and calla lilies, which are most prone to excessive drying during winter, start to wrinkle or shrivel, it’s time to dunk them in water and remoisten the vermiculite or peat moss so that it is slightly damp. It can also help slow down moisture loss, to place dahlias, and calla lilies in perforated plastic bags with some vermiculite or peat moss, then place the bags in a larger container with additional vermiculite or peat moss to reduce moisture loss.
In spring, divide rhizome and tuberous roots. Remove any dead areas, and make sure that each division has at least one growing point, or “eye”. Allow the cut sections to dry for a few days before replanting or potting.
University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office
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