Taken from Eclectic Gardener @ www.teachinggarden.org
Written by Alan Hickman

We’ve certainly had a mixed bag of weather these past couple of weeks. After a memorably sunny and pleasant long weekend, conditions went downhill like a rock off a cliff. Outside the built-up area, a series of fronts brought near gale force winds, lashing rain and, for a brief period, snow.
Uncomfortable though it was, when one considers what goes on around us, we really do seem to lead a charmed existence in this area. While we were having snow flurries, Buffalo got itself buried under two feet of the white stuff. In the midst of the resulting chaos of fallen trees, impassible roads and power outages, one resident there was moved to comment "Compared to St Louis, this is nothing." Compared to Buffalo, we’ve had picnic weather.
In the old section of town, the first turn-the-dahlias-to-mush frost came on the night of the 12th/13th. For the past couple of years, the inner city has been quite spoiled, escaping the negative digits well into the first week of November, but a killing frost in mid October is about the norm.
I don’t know if dahlias are actually becoming more popular, but, this year, I do seem to have been asked more questions than usual related to the storage and overwintering of the tubers.
Like all tender bulbs, tubers, corms, rhizomes etc., as soon as possible after the first hard frost hits, dahlia roots need to be dug and stored in a cool frost-free environment. That much is universally agreed to. As to how the storage is to be accomplished, opinions and practices vary.
Several years ago, when first I started growing dahlias, I followed the instructions of Ed Lawrence, at the time, Chief of Greenhouses and Grounds Services at the Official Residences in Ottawa. Ed recommended drying and packing the whole undivided roots in plastic grocery-store bags filled with vermiculite. This method definitely works.
The frost-bitten stems are cut off three or four inches above soil level and the dahlia roots are carefully dug so as not to damage the individual tubers. The tubers come out of the ground full of water and they snap easily. Also they have very tender, easily abraded, skins. Any loose soil is removed and the clumps are placed in trays in a single layer to ‘cure’.
The drying time needed to prepare the tubers for storage depends on the amount of soil packed around the tubers, the temperature, and the amount of air movement. As moisture in the tubers is lost, the skins wrinkle and toughen up and the tubers shrink. Experience is the best guide but as soon as the tubers feel dry to the touch and the skins don’t rub off, it is probably safe to remove any remaining soil and to pack the roots away.
Appropriately packed tubers need to be kept cool. The ideal temperature seems to be around 6C give or take a couple of degrees. As potatoes, carrots and other root vegetables also keep well at these temperatures, if you have an operating root cellar, your storage problems are over. For the other 99.9% of us, maintaining that low a temperature over the long term is a challenge.
If you are storing just a few tubers, the refrigerator crisper would likely do. Fridges are notoriously low in humidity so, even if they are wrapped in plastic, keep an eye on the tubers every few weeks to ensure that they don’t shrivel to lumpy dry strings. If you are carrying more tubers than will fit in the crisper, an old fridge in an unheated garage - rigged up with some sort of low-powered, thermostatically controlled, internal heater - could be arranged to keep the temperature just above freezing during the winter months.
Do whatever it takes to find the lowest temperature circumstances will allow. For instance, tight up against an outside basement wall with lots of insulation or blankets on the warm side will hold significantly cooler than the rest of the house.
One way to reduce the volume of tubers in storage is to divide the clumps before packing them away. After the clumps have cured, cut each tuber off making sure that a piece of the original stem is attached to the top of every tuber. Discard any tuber with a broken neck and any which come off without old tissue attached. Both of these will be ‘blind’ and neither will produce new shoots come spring. Let the cut surfaces dry and harden - usually a few hours or overnight. If the tubers are packed away all parallel to each other, they’ll take far less space than if left as a clump.
If you are really stuck for space, toss out the biggest tubers. It’s counter-intuitive but the size of the resulting plant is not greatly influenced by the size of the planted tuber and half-a-dozen or more small tubers will fit in the volume taken by one large tuber.