In our cold winter climates, dahlias need to
be dug and stored in order to survive. To lift
the roots, cut stalks to 4” above ground level
after the tops turn yellow or are frosted. Dig
a 2 ft. clump with spading fork, shake off loose soil, and let the clump dry in sun for several hours. From that point, follow either of the following methods.
Method 1: Divide clumps immediately. Freshly dug roots are easy to cut, and
eyes (growth buds) are easy to recognize at this time. To divide, cut the stalks
with a sharp knife, leaving 1” of stalk attached to each section; make sure each
division has an eye so it will produce a new plant. Dust cut surfaces with sulfur
to prevent rot; bury in sand, sawdust, peat moss, or perlite and store over winter
in a cool (40-45 degrees F), dark, dry place.
Method 2: Leave clumps intact. Cover them with dry sand, sawdust, peat
moss, or perlite and store in a cool, dark, dry place as directed in method above.
With this method, roots are less likely to shrivel.
About 2-4 weeks before planting in spring, separate intact clumps, cutting them
apart as described under Method 1. Then place all roots- whether fall or spring
divided- in moist sand to plump them up and encourage sprouting.