Expert: Long Island Gardener - 10/24/2006

Question
How can I keep my Dinner Plate Dahlias over the winter?  I live in New Jersey and they are still blooming.  Should I dig them up now?  Wait?  Forget it?

Answer
The first light frost is probably overdue for in your part of the Garden State.  So...

At your earliest convenience, which is probably today, cut down the flower stalks to about 3 inches.  Then, 10 days or so later, take your pitchfork and loosen the clump carefully, then dig the whole thing up.

I have to warn you: You can't be too careful about the way you do this.  You do not want to damage the Dahlia tuber. Be gentle.  Don't yank out the stem.  Dig it up, roots, stems and all.

Using a garden hose, spray the clump clean.  Using a scissors, cut the roots off.  Set the clump in a basement or heated garage and let the whole Dahlia clump dry.

You can store your tuber or try your hand at propagation.  This is the best thing going because you multiply plants you already have showned you can grow.

Cut the tuber with sharp scissors or a knife.  Carefully divide clumps in half by splitting with pruning shears.  The Swan Island Dahlias website (www.dahlias.com/index.asp?PageAction=Custom&ID=2#13) posts pictures of the whole propagation exercise.  Each tuber has one or more eyes.  Most are found somewhere near the stem.

You can make your own Dahlia Disinfectant to increase your chances of success with this.  Mix one cup of Bleach with 3 gallons of water and soak the cut up tubers for 15 minutes to 1/2 hour; place them on newspapers and set them out to dry in the kitchen or basement, out of the sun.

Some people overwinter their tubers in plastic bags with vermiculite.  Me, I prefer to keep them in peat moss in the basement, in an open plastic container, and mist them every few weeks with some water.

Keep the collection someplace dark and frost free. Store in a cool spot where temperatures don't go over 55 degrees F.  And wait for spring.

This works for all Dahlias, by the way.  Not just Dinnerplates.