How young are your trees? I had the same question since I was given a dozen freshly uprooted trees. They were on the border of being too young to be uprooted for winter, 18-39" tall, about 3 yrs old. So I repotted them and gave them on a heat mat hoping they are in a winter protected environment (heated greenhouse).
My other trees were uprooted. I pull them out of their pots and gently use a small hand rake to pick at the soil, not rake the roots. Get as much soil off as you can this way, then hose off the rest.
My tallest trees are about 12-14 ft tall. Once out of the pot and cleaned it us hoisted onto a sling of 2 large ropes about 3-4 ft apart to sleep away the winter.
Another way for smaller trees is to stand them into a large pot, as many as you can, tied together and cover the roots in perlite.
