Lifting and Storing Ground Dahlia Tubers
Lift the tubers in the autumn after the first frost, which often damages the parts of the plant above ground and blackens them. Cut off the main stems, about 6 in. above the ground, and with a fork carefully lift the tubers so that they are not damaged. Then remove any surplusfrom the roots and lay them upside down in a warm room or shed so that surplus water will drain out of the stems and the tubers dry off. Once the roots are dried and labelled store them in trays of dry sand or peat in a cool, frost-free place, such as a cool greenhouse, cellar, cupboard or slightly heated shed. Alternatively, place a layer of roots between two layers of straw in a large sack.
If there are a great many roots a clamp, like that used for, can be made.
Put down a layer of dry, clean straw on the soil in a sheltered position in the garden, heap the tubers on the straw, add more straw to a depth of 8 in. or so and finally cover with a layer of soil to protect the clamp from the rain.
Remember to label the plants when they are lifted. Write the name of each plant with a waterproof ink or pencil on a label made of metal, plastic or wood, and tie the label firmly to the stem. Alternatively, write the name in indelible pencil on the surface of a clean part of each tuber.