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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Overwintering Tender Perennials

This article was published originally on 9/26/2012

 
Gladioli, dahlias, cannas, and tuberous begonias are perennials, but they are not winter hardy in Iowa. Therefore, these tender perennials must be dug up in the fall and stored indoors over winter. The storage requirements for several widely grown tender perennials are provided below. 
 
Caladium 
 
Carefully dig up caladiums when the foliage begins to yellow with the onset of cool weather or wait until after the first frost. After digging, place plants in a cool, dry location for 1 to 2 weeks to cure. After curing, cut off the dead foliage. Place a layer of peat moss, vermiculite, or sawdust in a small cardboard box. Lay the tubers on the storage medium, then cover with additional peat, vermiculite, or sawdust. Store the caladiums in a cool (60 to 65 degree Fahrenheit), dry location. 
 
Calla Lily (Zantedeschia spp.) 
 
After a killing frost, cut off the foliage 1 to 2 inches above the soil surface. Carefully dig up the rhizomes. Do not cut or injure the rhizomes. Dry the rhizomes in a warm, dry location for 1 or 2 weeks. After drying, bury the rhizomes in peat moss or vermiculite and store them in a cool (50 to 60 degree Fahrenheit), dry location. 
 
Canna 
 
Cut the plants back to within 4 to 6 inches of the ground a few days after a hard, killing frost. Then carefully dig up the canna clumps with a spade or garden fork. Leave a small amount of soil around the cannas. Allow them to dry for several hours. Afterwards, place the cannas in large boxes, wire crates, or in mesh bags. Store the cannas in a cool (40 to 50 degree Fahrenheit), dry location. 
 
Dahlia 
 
Cut back the plants to within 2 to 4 inches of the ground within three or four days of a killing frost. After cutting back the plants, leave the dahlias in the ground for an additional six or seven days to "cure." Then carefully dig up the dahlias with a spade or shovel. Gently shake off the soil, then cut the stems back to the crown. (The dahlia crown is located at the base of the stem where the tuberous roots are attached.) Carefully wash the dahlia clumps to remove any remaining soil. Allow the dahlias to dry for 24 hours. When dry, place the dahlia clumps upside down in cardboard boxes and cover them with vermiculite, peat moss, or wood shavings. Store the dahlias in a cool (40 to 50 degree Fahrenheit), dry location. 
 
Elephant's Ear (Colocasia esculenta
 
Dig up the plants after the first fall frost. Cut off the foliage. Dry the tubers in a warm, dry location for 1 or 2 weeks. After drying, bury the tubers in peat moss or wood shavings and store them in an area with a temperature of 70 to 75 degrees Fahrenheit. 
 
Gladiolus 
 
Carefully dig up the plants with a spade in late summer/early fall. Gently shake off the soil from the bulb-like corms. Then cut off the foliage 1 to 2 inches above the corms. Dry the corms for 2 to 3 weeks in a warm, dry, well-ventilated location. When thoroughly dry, remove and discard the old dried up mother corms located at the base of the new corms. Remove the tiny corms (cormels) found around the base of the new corms. Save the small corms for propagation purposes or discard them. Place the corms in mesh bags or old nylon stockings and hang in a cool, dry, well-ventilated location. Storage temperatures should be 35 to 45 degrees Fahrenheit. 
 
Tuberous Begonia 
 
Carefully dig up the tuberous begonias within a few days of a killing frost. Leave a small amount of soil around each tuber. Cut off the stems about 1 inch above the tubers. Place the tubers in a cool, dry area to cure for 2 to 3 weeks. After curing, shake off the remaining soil. Place a layer of peat moss, vermiculite, or sawdust in a small cardboard box. Lay the tubers on the storage medium, then cover the tubers with additional peat, vermiculite, or sawdust. Store the tubers in an area with a temperature of 40 to 50 degrees Fahrenheit. Do not allow the tubers to freeze.