I bought some blueberry bushes in pots this fall to plant in my yard. I waited until all their leaves dropped before transplanting, but now the pots/root balls are frozen solid. Is now still an okay time to transplant, or should I just hold onto them until early spring at this point? (Lower Mainland BC, it's supposed to drop down to around -10 next week at night.) The plants themselves are fairly large, about 3 feet tall but the pots are *small*, maybe a half gallon so they are very root bound and I'm worried that disturbing the roots while frozen is not good.