Just before or immediately after the first killing frost you may cut dahlia plants to a level of 10 cm (4 inches) from
the soil surface. The plants are easily composted. If you plan to store the clumps over winter and divide in the
spring digging can begin immediately. The tuber mass can be carefully trimmed back so as to remove very small tubers,
excess stalks and fine roots.
If the clumps are to be divided in the fall it is advisable to let the tubers remain in the soil for several days
to allow time for the "eyes" to develop. Well developed eyes will greatly assist in dividing the tubers before storage.
Tubers of some varieties are very long. Care must be exercised when digging so as to not slice through the tubers.
Some people recommend using a shovel while others a garden fork. Both work well.
A good wash with a garden hose will make trimming and dividing of dahlia clumps easier. Compressed air can be very
effectively used to blow the dirt off dahlia clumps. Be certain that the air pressure is well regulated as excessive
pressure can cause tuber damage.
In areas with mild winters, it may not be necessary to dig dahlia tubers in the fall. If there is no ground frost and
the soil has good drainage the tubers may survive very successfully overwinter. These clumps of tubers should be
carefully lifted in the spring, divided, and a good tuber replanted. It is always best to plant a young tuber with an
obvious eye or new shoot and not the mother tuber from the year previous..
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