Hardiness zones, also known as “gardening zones” and “growing zones,” are a set of numeric designations that identify a narrow set of climatic conditions. Most of these systems are based on the average annual lowest night temperature. The lower the number, the colder the average nighttime temperature. 

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In your yard, you could create a microclimate with a different zone by planting in a well-protected spot in your yard. For example, the southeastern side of your house or fence where the structure gives the area a little bit more protection than if the structure wasn’t there.

Soil is a great heat source to take advantage of if you want to change a zone. The top of the soil might be frozen in the middle of the winter, but below the surface the heat from down below radiates upward to heat the plant’s roots.

Another way is to mulch the plant early. Mulching will create another couple of inches of insulation to keep it even warmer. Most times I would tell people to mulch after a good hard freeze to hold the cold in and keep the temperature around the roots and plants crown an even temperature. However, you can protect a marginal plant for your area by mulching early. Rose collars are a great way to keep the mulch in place

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Wrapping a plant will also help if you ensure the wrap can breathe, and that the wrapping goes to the ground. If it doesn’t go all the way to the ground, then all that it is doing is breaking the wind and not trapping heat.