Zone 4 is not as cold as it gets in the continental USA, but it’s still pretty cold. That means that plants requiring warm climates need not apply for positions in zone 4 perennial gardens. What about azaleas, those foundation shrubs of so many flowering gardens? You’ll find more than a few varieties of cold hardy azaleas that would thrive in zone 4. Read on for tips about growing azaleas in cold climates.
Growing Azaleas in Cold Climates
Azaleas are beloved by gardeners for their showy, colorful flowers. They belong to the genus Rhododendron, one of the largest genera of woody plants. Although azaleas are most often associated with mild climates, you can start growing azaleas in cold climates if you select cold hardy azaleas. Many azaleas for zone 4 belong to the sub-genus Pentanthera. One of the most important series of hybrid azaleas available in commerce is the Northern Lights Series. It was developed and released by the University of Minnesota Landscape Arboretum. Every one of the cold hardy azaleas in this series will survive down to temperatures of -45 degrees F. (-42 C.). That means that these hybrids can all be characterized as zone 4 azalea bushes.
Azaleas for Zone 4
If you want zone 4 azalea bushes that stand 6 to 8 feet (2 m) tall, take a look at Northern Lights F1 hybrid seedlings. These cold hardy azaleas are extremely prolific when it comes to flowers, and, come May, your bushes will be laden with fragrant pink flowers. For light pink flowers with a sweet smell, consider the “Pink Lights” selection. The shrubs grow to 8 feet (2 m.) tall. If you prefer your azaleas a deep rosy pink, go for “Rosy Lights” azalea. These bushes are also about 8 feet (2 m.) tall and wide. “White Lights” is a type of cold hardy azaleas offering white flowers, hardy to -35 degrees F. (-37 C.). The buds start out a delicate pale pink shade, but the mature flowers are white. Bushes grow to 5 feet (1.5 m.) tall. “Golden Lights” are similar zone 4 azalea bushes but offer golden blossoms. You can find azaleas for zone 4 that were not developed by Northern Lights too. For example, Roseshell azalea (Rhododendron prinophyllum) is native to the northeastern segment of the country but can be found growing in the wild as far west as Missouri. If you are ready to start growing azaleas in cold climates, these are hardy to -40 degrees F. (-40 C.). The bushes only get to 3 feet (1 m.) tall. The fragrant flowers range from white to rose pink flowers.
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Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.