By Jim Klett, Colorado State University Cooperative Extension Specialist, Landscape Plants
At the end of the growing season, tuber-grown dahlias should be dug and stored for the winter in a frost-free place. Immediately after the first frost and after leaves have blackened, cut the stem back to about six inches above the ground. Then use a fork to loosen the soil around the tuber and lift out of the soil. Remove surplus soil from the tuber.
Place the tubers upside down in a dry airy space for about two weeks. This allows moisture to drain out of stems. The tubers need to be completely dry before they are stored for the winter. Next store the tubers in trays of dry sand or peat moss in a cool, dry cellar or storage area at about 40 to 45 degrees F. Never store at a much higher temperature, as dahlia tubers will dry out and shrivel rapidly.
Another method of storing includes placing tubers in a heavy-grade, black plastic bag without additional packing material. Then seal the bag. This will prevent the tubers from dehydrating. Keep the tubers in a frost-free area. The danger exists, however, that they will sweat and rot.
Inspect the tubers every few weeks during the winter to check for disease or shriveling. Cut off any diseased parts and, if the tubers have shriveled, place them in a bucket of water overnight to plump them up. Allow them to dry thoroughly before returning them to storage.
Photographs courtesy of Judy Sedbrook.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010