The cold hardiness rating is usually based on our experience at Camellia Forest. The zone
corresponds to the temperature that the plant will tolerate without cold injury. The
microclimate is quite important since wind protection and winter shade make it possible
to grow marginally hardy plants successfully that would not thrive in exposed sites.
Our advice for growing plants with borderline hardiness is to plant in a
protected spot and mulch well.

Find a more detailed map here.