Over recent years many people have successfully left the tubers of Dahlia in the ground without loss. In sheltered sites with a good layer of protective mulch this works very well with plants getting away in the spring quickly and the tuber expanding without disturbance. If you live in a more exposed location then your best bet is to lift the tubers after the first frost has killed of the foliage. For those of us who do lift Dahlia's now is a good time to check that the tubers have dried out well and are looking healthy. Unwrap the tubers and check they have dried well and do not have areas of mould or rot amongst them cutting away tubers that appear damaged. Tubers, which look to have shrivelled, can be plunged in a bucket of water overnight and those which do not plump back up should be discarded. There are lots of ways to store the tuber but I tend to lift, remove excess soil, label and wrap in newspaper for winter, in early spring I set them out, partially covered in trays of compost and water sparingly until shoots appear. These shoots make excellent cuttings. ;
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