How do I keep dahlias over winter?
Winter care for dahlias begins with the first light frost. Cut the stems back to about 1 foot above the soil. Dig the plants out, being careful not to damage the tuberous roots. Gently remove any loose soil and let the plants air-dry for several hours. After removing any damaged or diseased areas, cut back the stems 3 to 4 inches above the tuberous roots. Pack the roots in sand or vermiculite, and store them for winter in a refrigerator or a cool dark location with temperatures around 45°. In spring, divide the tuberous roots before planting. Be sure to leave at least one “eye” for every division.