Winter Azalea Care: Learn Simple Ways to Keep These Plants Healthy

The gorgeous, spring bloom of azaleas is often associated with a mild climate—but in fact, there are azaleas that can be grown even in areas with subzero winters. All you need to do is select a suitable variety and provide it with some protection in the winter. 

Read on to learn all about winter care of azaleas. 

Select a Winter-Hardy Variety

The many azalea varieties, which all belong to the Rhododendron genus, vary greatly in winter hardiness—some survive a freeze and others easily suffer cold damage. It is crucial that you pick one that is suitable for your USDA growing zone.

Azaleas suitable for zone 4 include:

• ‘Northern Lights’: A series of hybrids bred by the University of Minnesota. They come in a wide range of colors and the flower buds and withstand temperatures of minus 30 to minus 45 degrees F.
• The ‘Encore’ series: Named after their repeated bloom in spring, summer/fall, withstand temperatures between minus 5 and 0 degrees F and are suitable to be grown in zone 6.
• Pinxterbloom azalea (Rhododendron periclymenoides): Native to the eastern United States and hardy to zone 4.

Regardless of the variety’s cold hardiness, it is always a good idea to plant an azalea in a spot where it is sheltered from icy winter winds.

Signs of Winter Damage on Azaleas

Don’t panic if your azalea bush drops its leaves in the fall or winter—there are deciduous and evergreen varieties and leaf drop is normal in both types, even in evergreen azaleas. Some leaf curl on cold days is also a normal occurrence.

There are, however, signs that your azalea is suffering from the cold, which should prompt you to take immediate action to prevent further winter damage. Sudden extreme temperature drops are especially harmful, and the younger the shrub, the more vulnerable it is to winter damage.

Telltale signs of cold damage are a split bark and, on evergreen azaleas, dried leaves that have been desiccated by icy winds or excess sun when the foliage of deciduous trees which usually cast shade on the shrub, is not present. 

Will Azaleas Rebloom in the Spring?

If you have planted an azalea variety suitable for your climate, it will rebloom in the spring. In an exceptionally cold winter, or a winter with dramatic temperature fluctuations, the buds may suffer some cold damage. This may reduce the bloom in the following year, but this is temporary, and the plant usually recovers.

Cold damage is not the only reason that an azalea fails to bloom in the spring. It can also be caused by incorrect pruning. Azaleas bloom on old wood (last year’s growth) and pruning should be done immediately after the azalea finishes blooming to eliminate the risk of accidentally removing flower buds. 

Winter Protection for Azaleas

Stop Fertilizing

Do not fertilize your azalea after mid-summer, by August the latest, as this will trigger new, tender growth that is especially susceptible to cold damage after the fall temperatures drop in the fall. This also applies to re-blooming varieties like ‘Encore’.

Reduce Watering

Follow this specific watering regimen in the fall to prepare your azalea for winter.

• If rainfall is not sufficient and you usually water your azalea, gradually reduce the watering in the fall by one-third, which toughens the plant for winter.
• After the first two or three hard freezes but before the ground is frozen, give it a thorough soaking. Watering as the plant enters dormancy helps to protect it against winter burn caused by moisture loss. 

Protect Azaleas Against Wildlife

Cold weather is not the only enemy of azaleas in the winter. Deer, rabbits, and other wildlife will seek it out, especially if there is a snow cover and other food is scarce.

To protect the plant, gently tie the branches together toward the center. Use hardware cloth to form a fence all around the plant and bury it in the soil to prevent critters from digging underneath.

This type of protection is only practical for smaller, younger azaleas which is also the stage at which they are the most vulnerable to browsing. Established shrubs usually appeal less to the taste buds of most critters. Remove the wire fencing in the spring when the plant has started leafing out. 

Add Mulch

Wait until the first hard freeze to spread a 3 to 5-inch layer of mulch around the plant, a circle that is wide enough to cover the entire root zone. Wood chips are best as they remain in place, unlike lighter much such as straw or dry grass.

Do not let the mulch touch the trunk of the plant, as this traps moisture and can cause the bark to rot; it also invites critters. There is no need to remove the mulch in the spring, as it helps preserve soil moisture, suppresses weeds, and keeps the soil cool during the summer. 

Wrap the Plant

Wrapping your azalea in fabric for the winter is unsightly and should only be the last resort if the azalea variety is borderline winter-hardy in your zone, if it’s a newly planted or transplanted azalea, or if severe weather conditions such as heavy snowfall or ice storms are common occurrences in your location.

• Before the ground freezes, securely drive three or four sturdy stakes into the ground around the plant.
• Drape a porous material (burlap, old bed sheets, or any other cotton cloth) around and above the stakes, creating a tent.
• Secure the material with ties so it does not blow away.

The cover should not have direct contact with the plant; this can lead to breakage and constrict the airflow. Do not use polyester fabrics as they do not breathe and trap heat, roasting your plant on a sunny day.

Winterizing Potted Azaleas

Azaleas in containers are more susceptible to cold damage, even if the variety is hardy to grow in zone 4. In pots, their roots are insufficiently insulated against the cold, which damages the roots and kills the plant.

Just moving the pots inside your home is not an option as azaleas need a certain number of chill days in order to bloom and indoor temperatures are too warm. They are different from florist azaleas which are not meant to be grown outside.

There are different ways to protect the roots. Either move the potted plants to a location where the pot is protected from frost, such as an unheated garage, sink the container in the ground, or place it inside a planting silo. For larger containers, it is more practicable though to wrap the container with bubble wrap or burlap.

If your winters are mild, keep watering your potted azaleas to prevent them from drying out but never water them when the potting medium is frozen.