This means the our frost-free growing season in 2009 ran from the first week of June (we had frost the week after Memorial Day that nipped a bunch of tomato plants in the vegetable garden) until mid-October, a total of about 19 weeks (or 133 days). I always think that our growing season is so short, but that's almost five months! Not bad.
This coming weekend I'll dig the dahlia tubers and store them in the basement over the winter.
A little advice from the Old House Gardens Web site on storing dahlias:
If you want to save tubers for replanting the next spring, after the tops have been “blackened” by frost, wait a week or so for the tubers to harden and fully mature in the ground. The soil will generally protect them from freezing. Then cut the stalks off a few inches above ground level. You’ll find that the tubers you planted in early summer will have increased into much larger clumps, so be careful when digging – start at least a foot away from the stalks. Tag each clump with its name, wash off all soil, and allow it to dry upside down in a cool, dry place for a day or two, no more.As for me, I'll most likely bury the tubers in peat moss in a Rubbermaid tote that I will store in the basement (ah, the blessing of a dirt-floor basement; cool winter storage!).
Divide the clumps with a sturdy knife in fall or spring. Be sure a piece of the “crown”—the thickened area where the stem meets the tuber—remains attached to every clump, because the eyes (often more visible in fall) are located there. You may want to dust cuts with a fungicide such as garden sulfur. At the least allow cuts to air dry for a full day before storage.
Store in plastic grocery bags, in plastic garbage bags inside boxes, or in covered plastic storage boxes to help keep the tubers from dehydrating. Pack in coarse vermiculite, peat moss, wood-shavings, or something similar. Store in a cool, dry, dark place, ideally at 40–45º F. Check every now and then. Allow excess moisture to escape (look for condensation) or sprinkle some water on tubers if they seem to be shriveling.
Or here’s an easy way recommended by Marian and Bernard Mandella and Richard Peters in the Bulletin of the American Dahlia Society, September 2001. “Tear off a sheet of plastic wrap 20 or more inches long and lay it flat on a level surface. Place a [divided, dusted, and dried] tuber on one end and roll the plastic wrap over one complete turn. Lay another alongside and roll again. Be certain that no tuber is touching another…. You may wrap up to five tubers or so per package, but in the last 5-7 inches, fold over the side portions of the plastic wrap and continue to roll to completion. Fasten with a piece of masking tape that is labeled with the cultivar’s name. . . . There is essentially no loss from shriveling or drying.”
Some of our customers who grow dahlias in pots just bring them inside and let them dry out and over-winter right in their pots. Others grow them in 5-gallon or even 1-gallon black plastic nursery pots that they bury in the garden and then dig up and store in the basement through winter. You may want to experiment with these extra-easy storage methods, too!