While gardeners in zones 8 and above can grow tender bulbs, corms, rhizomes and tubers year round, northern gardeners will need to dig and store these plants to overwinter them. There are no absolute rules for overwintering the tender plants but in general:
- Keep them dry and above freezing temperatures.
- Don't store in air tight containers that could cause moisture build up and rot or fungus.
- Check regularly for desiccation and mold.
- Remember to label by type and color.
Below are more specifics for some commonly grown tender bulbs, corms, rhizomes and tubers.
- Alocasia (Elephant's Ear) Easiest to simply treat as potted houseplants. Feed lightly throughout winter and water often. If ground grown, lift and pot before frost. Alocasia tubers can also be cleaned and stored in peat moss, in a cool, dry spot. Plants tend to get larger as the tubers age. Repot in early spring.
Anemone coronari (Windflower) Follow guidelines given for storing dahlias. Bulbs are often sold in the fall, but they are not hardy in Zones 5 and lower.
Begonias, Tuberous Allow a frost to kill the tops, but do not allow the tubers to freeze. Lift and let tubers dry for one week, with about 5 inches of the foliage still in tact. Remove excess soil and foliage and store in peat moss or sawdust at 50 degrees F. Repot in early spring and keep warm, 68 - 75 degrees F. Move to a sunny spot when shoots appear. Keep evenly moist, but not wet. Plant outside after all danger of frost.
Caladium Lift caladium plants before frost and allow them to dry in a warm spot. Cut back the foliage after it dies. Caldium bulbs don't like to be stored in cold temperatures. Keep at 50 - 60 degrees F. Pack loosely in peat moss. Repot up in early Spring, about 2 inches deep, knobby side up. Keep the soil moist and warm - 75 - 80 degres F. Move outdoors after all danger of frost.
Canna Allow frost to kill the tops, but do not allow the rhizomes to freeze. Carefully lift the plants and cut off the dead tops . Hose off excess soil and allow to dry. Rhizomes can be wrapped in newspaper and stored in paper bags or cardboard boxes, at 45 to 50 degrees F. Very easy to overwinter. Cannas can be divided by hand. Break apart, insuring there are at least 3 eyes per division. Repot in early spring or plant directly in the garden once the temperatures remain above 70 degrees F. Keep well watered.
Colocasia esculenta Taro Like Alocasia, Colocasia can be brought indoors as a houseplant or dug and overwintered as a tuber. Store the dried tubers in peat moss. Check the tubers monthly and cut away any soft spots that may develop. Allow the remaining healthy portion to dry before restoring in peat. Colocasia can be repotted about 8 weeks before the last expected spring frost. If dividing, be sure each tuber piece has a corm. Allow the tubers to dry a few days before replanting them.
Dahlia Dahlias can be over-wintered in the ground with sufficient mulch, but it is risky. To store dahlias, they must be dug before a hard freeze, but their tops may be allowed to die back from a light frost. It's easiest to see the dahlia eyes, for division purposes, within a week after the tops are cut or killed back. These tubers don't like to get completely dried out. Overwinter in peat moss and check monthly for dehydration . Mist lightly, if necessary. Dahlia tubers are usually direct planted in the garden, once temperatures warm.
Galtonia candicans (Summer hyacinth) Dig bulbs anytime in the fall. Overwinter in peat moss. Replant offsets directly in the ground, after all danger of frost.
Gloriosa superba (Glory Lily) Store in peat moss. Check the tubers monthly cut away any soft spots that may develop. Allow the remaining healthy portion to dry before restoring in peat. In general, use the same guidelines as dahlias. You can repot Glory lilies after only 2 months of storage or hold until early spring.