How can I over-winter container grown trees and shrubs?  

Question:

How can I over-winter container grown trees and shrubs?  

Answer:

If a woody tree or shrub cannot be planted in its final spot before winter arrives, you will need to take steps to make sure it survives the winter while still in the container.

The roots of most trees and shrubs are far less cold-hardy than their aboveground stems or trunks. Cold temperatures may damage or kill the plant if container-grown plants are left above ground in winter.  

One option is to bury the container.  An excellent way for home gardeners to over-winter container-grown trees and shrubs is to dig holes in a garden area and set the pots in the ground. Plants overwintered in containers should be heeled into the ground after they go dormant but before the soil freezes. 

Container-grown trees and shrubs can also be overwintered by placing them in a moderately cold location (20 to 45°F) over the winter months. The cold temperatures will keep the plants dormant until spring. An attached, unheated garage is often a suitable over-wintering location if you are confident the temperatures can stay consistently in the 20 to 45 degrees Fahrenheit temperature range.  Many unheated structures can vary more widely in temperature than this.  It is important to monitor and adjust temperatures inside the structure if needed.

Learn more about overwintering unplanted plants in this article: Overwinter Unplanted Trees, Shrubs, and Perennials.