Spring will be here in no time. These bags are sold on Amazon in France for potted Citrus, which can be a bit tender. Since we had un-heard of (rarely) snow this year I bought two. Just for citrus. They have all sizes. Check out Amazon.com to see if you have them in the states. Such an easy idea.
I would buy them for my apricots and peach trees (dwarf root stock) if I was still in the NE.