I live just north of Toronto, Canadian Zone 6, Min average temp is -23 to -20, something in that range, so we are probably looking at a USDA zone 4b or 5a...

Needless to say, every year I faithfully dig my tubers, and last fall was no different.... at least for the ones I wanted to keep! I did not dig "all" as some I found did not perform as well as expected and I figured I would just let them go as opposed to bother digging them up... We had a very cold wet winter and spring, one of the coldest and wettest I can remember in years!

Imagine my surprise when this weekend I went to clean up my garden this weekend and saw a number of old dried out dahlia stems that were absolutely dead, but did not come up easily when I tugged on them... Indeed, they where cemented into the ground, and when they finally gave, it was pulling up with a clump of fresh solid tubers!! I stopped yanking on them, dug a few clumps up, and found indeed... the tubers overwintered!!

How could this have happened I wondered.... I think it is because last spring, I planted them really deep, at least 10 inches down, they must have been protected at this depth... I am going to begin experimenting over the next few years to see if there are ways I can keep them dug deep overwinter, storing them indoors is a total pain! That said, I know I am risking my tubers... But long winters in less then ideal storage conditions is also a risk, and a whole heck of a lot more work!!