Protecting Your Broadleaf Evergreens from Frost Damage

October 31, 2023

Tree Care

The Eliot and Linda Paine Rhododendron Discovery Garden at the Holden Arboretum has many evergreen Rhododendrons and Azaleas. These plants, although winter hardy, are still susceptible to frost damage, and it is common for their leaves and buds to be harmed at low temperatures. Exposure to winter winds often cause desiccation, or too much water evaporation from the leaves at once. This leads to the formation of unattractive dark spots on the leaf surface or curled leaves that are unable to unfurl. Luckily, there are several ways you can protect plants from winter chill.

Organic Materials & Creative Fencing

One important step you can take to prevent leaf desiccation is to water and mulch your plants in the late fall before any ground freezing occurs. Two inches of organic mulch, like woodchips or straw, applied over the root zone will insulate the soil and protect the roots. Another thing you can do is build fences to shelter your Rhododendrons from the wind. Here at Holden, we protect our Rhododendrons and Azaleas with fences made from wooden stakes and burlap. An example of one of these fences can be found in the picture below.

Figure 1: A burlap fence used to shield Rhododendrons from winter chill.

Broadleaf Evergreen Blankets

If you do not have the materials or space to build a fence, you can use the branches of pine trees to cover your Rhododendrons. The branches act as a blanket and help to insulate your plants. If you take a walk through the Rhododendron Discovery Garden, you will see many of these pine branch blankets protecting our Rhododendrons and Azaleas as well.

Figure 2: Rhododendrons with Pine branch coverings.

Anti-Desiccant Treatments

Anti-Desiccants are purchasable sprays designed to help plants survive harsh winters. They work by coating plant leaves with a waxy coating that prevents water loss from a plant’s foliage. Keeping the leaves from drying out helps the plant stay safe from frost damage.

Nicholas Chilson

Garden Technician

Nick Chilson is an arboretum Garden Technician. He works in the Eliot and Linda Paine Rhododendron Discovery Garden. He began working at Holden Forest and Gardens March 2022.

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