Is it a recent purchase and was it outside when you bought it? Or have you had it outside in a pot? If so, plant now, as long as the ground isn't frozen.

I agree

Shrubs settle in better if planted in autumn (or the mild parts of early winter). Don't forget to water it in and then water it regularly all next year. Use rainwater if possible.

At the moment they are dormant with no leaves, I dont think it will make any difference in fact it would do better in the ground with more protection from the frost on its roots. Plant it away from draughts that is the only thing that seems to bother them, I have three one in the sun and two in the shade facing north they are all well established trees now.