I bought an owari satsuma in the spring. It has grown nicely and its three oranges are turning yellow. I have it in a large pot up against the south side of my house. So far we've had a couple of frost nights so I created a teepee with a blanket and heavy plastic, both of which I removed during the day. But now we're in for a cold, rainy stretch with lows around 3°. Should I keep it covered?