Here in NW Washington I generally let my dahlias overwinter in the garden, and dig & divide the clumps every couple of years in the fall. However, last fall I got busy & let everything stay in the ground. Then we had a cold wet winter. Most of the clumps are fine & beginning to sprout & they can stay where they are for this year (again), but there are some in the lower end of the garden where it is soggy, that did not do so well, and there are some clumps that are getting too big & need to be split. I would like to lift these now (April), take a look, & divide out & replant the "good parts."

The problem is that in the past when I have dug the tubers & divided them in the spring & then replanted, the plants have been weak (or have died). Any advise?