Dahlias are cheerful garden flowers that grow from tubers. They lack cold-hardiness, so in the fall the tubers must be dug up and carefully stored until they may be replanted in the spring. Gardeners often make the mistake of digging up dahlia tubers too early. Tubers from plants that are still green won't store properly.
The first hard frost of fall kills the foliage. Dig the dahlia tuber immediately thereafter.
Use the pruning shears to cut the dahlia's stem to 4 inches from the surface of the soil.
Dig into the soil, 1-foot away from the dahlia, in a circle around it. Use the gardening fork to gently pry the tuber from the soil.
Rinse the soil from the tuber and cut the stem all the way to the tuber.
Place the tuber in a mesh bag and hang the bag in a cool, dry area. Allow the tuber to remain there until it is dry, about three weeks.
Dust any damaged tubers with fungicide. Use either a small paintbrush to apply the powder, or place the powder in a small bag, drop in the tuber, close the bag and shake it gently until the tuber is covered with powder.
Place newspaper into the box and flatten it at the bottom and up the sides.
Pour sand into a planting pot and sprinkle water over it. You don't want the sand to be thoroughly wet, just barely moist. Pour a 2-inch layer of sand onto the newspaper on the bottom of the box.
Lay the tuber on the sand. If you are saving more than one tuber, place them side by side but not touching.
Pour another 2-inch layer of the sand over the tubers, close the box and place it in a cool, dark area. Ideally, the temperature should remain at 4.44 to 7.22 degrees Celsius.