That very much depends where you are in the UK Shh.
Welcome to GoY too.

It is a tuberous type and is not frost hardy. So if you do put in the ground you would have to lift it before the autumn frosts or it would die. I would have it in a decorative pot if it were me.

If you do opt for a pot make sure to lift it before storing for winter and check for vine weevils, the grubs just love begonia tubers