Every year somebody predicts a hard, cold winter. If they are right this year, the roots of plants such as Dahlias will be killed when the soil freezes. To keep them safe you should lift the root tubers and store them indoors until spring. As soon as their stems are blackened by frost, dig up the plants carefully, avoiding root damage. Gently shake off the loose soil, and cut the stems back to about 15 centimetres. If you have different varieties label them with their names and colours right away – you may well forget which one was which before spring. Stand them on wire mesh or similar in the greenhouse for a few days to dry off fully. Then place them upright on a layer of dry peat or soil in containers, filling more in around them to cover the tubers. Keep them dry and cool but frost-free under staging until spring, and then divide and plant them out a fortnight or so before the last likely frost date for your area. If you want to take cuttings, start them growing in the greenhouse in February and use the new shoots as cuttings when about 75mm high.