Dahlia tubers, ranunculus corms, and anemone corms are not winter-hardy in most climates. To keep them year after year, you need to lift and store them over winter.
Wait until the first hard frost blackens the foliage (for dahlias) or until foliage dies back naturally (for ranunculus and anemones). Cut stems back to a few inches and carefully dig tubers or corms with a garden fork, working from the outside to avoid damage.
Rinse off soil gently. Let tubers/corms dry in a sheltered spot for 1–3 days. For dahlias, this curing period helps the skin toughen. Remove any rotten or damaged pieces. Some growers dust with sulfur to prevent fungal issues.
Pack in slightly damp (not wet) peat moss, vermiculite, or wood shavings in a cardboard box or plastic bin with ventilation holes. Store in a cool (40–50°F), dark, dry place. A basement, unheated garage, or root cellar works well. Check monthly—discard any that are rotting and mist lightly if they are shriveling.
Dahlia clumps can be divided in fall at digging or in spring before planting. Each division must include at least one eye (growth bud), which is found at the junction of the tuber and the stem. Dividing annually increases your stock for free.
In spring, inspect stored tubers and corms. Discard any with rot. For dahlias, start in pots indoors 4–6 weeks before last frost, or plant directly after frost. For ranunculus, pre-sprout corms before planting. For anemones, soak before planting.