Posted by Brooks Wilson on 11/4/2017 to FAQ (Frequently Asked Questions)
Azaleas have always been a staple in southern gardens, however, with the introduction of many new and more cold hardy Azalea varieties, these flowering beauties are moving their way north to new markets. While most Azaleas are cold hardy to USDA Zone 7 or 8, meaning they will tolerate low winter temperatures to 0 to 5 degrees Fahrenheit, we now offer a few varieties that are cold hardy as far north as USDA Zone 5, which has low winter temperatures to -20 degrees Fahrenheit.
In USDA Zones north of Zone 5, where low winter temperatures drop well below -20 degrees Fahrenheit, you can grow any Azaleas in containers that can be overwintered in an interior space where temperatures don't drop much below 20 degrees F. If you're a Zone 4 risk-taker, you may have luck growing Zone 5 azaleas outside year round, but plant parts above ground can and often will be damaged or killed during a harsh winter. If you're in Zone 4 and just have to try an azalea, make sure to plant in a site that provides at least 6 hours of direct sunlight per day during the winter and insulate the roots in late fall with a 4 inch protective layer of mulch that is removed when temperatures warm in early spring. SEE: How To Protect Outdoor Plants From Freezing During Winter
Below is a list of the Azalea varieties known to be cold hardy in USDA Zone 5...