Digging up Dahlia Tubers

Dahlias are not winter-hardy in most of the US. In USDA zones 7 and colder, dig the tubers each fall and store them indoors; in zones 8 and warmer they can usually stay in the ground if the soil drains well. This video shows the digging process.

1. Timing: Wait until the first frost blackens the foliage. That happens anywhere from September to November depending on where you live; check your average first frost date with the zone and frost date lookup. Many growers then wait another week or two before digging, which lets the tuber skins toughen for storage. Dig before the ground freezes.
2. Cut back: Cut the stalks to 4 to 6 inches above the soil. The stems are hollow; tip each clump upside down for a while after digging so any water inside drains out instead of rotting the crown.
3. Digging: Loosen the soil in a circle about a foot out from the stalk. In this video I use a small spade to dig under, leaving ample space to avoid damaging the tubers. Lift the clump from underneath, not by pulling on the stalk, since the tuber necks snap easily.
4. Cleaning: Shake off loose soil and gently rinse the clump with water. Let it dry for a day or so somewhere cool and out of direct sun, but above freezing.
5. Dividing (optional): New growth comes from eyes on the crown, the old stem base where the tubers attach, not from the body of the tuber. Each division needs a piece of crown with at least one eye, an unbroken neck, and a firm tuber. A tuber that breaks off without crown attached won't sprout. Eyes are hard to see in fall, so many growers store whole clumps and divide in spring, when the eyes have swollen.
6. Storing: Store tubers in a cool, dark place that stays around 40 to 50°F, such as a basement or insulated garage. Pack them in peat moss, vermiculite or wood shavings in a box or bin so they neither rot nor shrivel. Label each variety.
7. Checking: Look at them once a month through winter. Mist shriveling tubers lightly; cut away soft or moldy spots, or discard tubers that have rotted.

In spring, replant the tubers after your last frost, once the soil has warmed.