If they are already happy in a pot, you can keep them in a protected place in a garage as long as the temp is above a hard freeze. I kept some bare roots I had purchased from a garden center for 75 cents each in a refrigerator crisper tray over winter then planted them at the first warming of the soil. 11 out of 12 survived and the one which failed was the one I dug early to see if it was growing. Some vendors keep them in cold storage over winter and sell them in spring. I would not plant them if freezing soil is imminent even though the conventional wisdom is plant them any time the ground is not frozen. If you have several, split them into two groups and plant one but store the other. That way you can only be half wrong.
