Be aware that a tree that has insufficient root systems are more vulnerable to dieback in the winter, possibly to the ground...Pino's advice is spot on (put it in a container).
Last winter, Two different winter protected trees died back to the ground on me due to either digging up, or putting a new airlayer inground before the winter....and that was an Hollier. It was a mild zone 8a/b winter, they were protected like all my young trees, temps did not get below 25F.