What is an antidesiccant?

An antidesiccant, also called an anti-transpirant, is a protective spray that reduces water loss from plant foliage during winter. It forms a thin, flexible film over the leaves and needles that slows moisture escape while still allowing the plant to breathe. Broadleaf evergreens and conifers benefit most, especially in exposed sites where drying winds accelerate stress.

How do antidesiccants protect trees and shrubs in winter?

Antidesiccants protect trees and shrubs in winter by forming a semi-permeable coating on the foliage that reduces transpiration, the process through which plants release moisture. When the ground freezes, roots cannot replace water lost through the leaves, and this imbalance leads to winter burn. The film slows that loss, helping evergreens hold moisture until the soil thaws.

When should antidesiccants be applied?

Apply antidesiccants in late fall or early winter, after plants have hardened off and gone dormant but before temperatures drop below freezing. The ideal window is a dry day between 40 and 50 degrees Fahrenheit with no rain in the forecast, giving the coating time to dry. A second application in late winter often extends protection.

Which plants benefit most from antidesiccant treatment?

Broadleaf evergreens such as holly, boxwood, rhododendron, and azalea benefit most from antidesiccant treatment, along with many conifers like arborvitae, juniper, and cypress. Newly transplanted and young trees are also good candidates, as are tender stems on roses and hydrangeas. Plants in windy, exposed locations tend to see the greatest benefit.

Are there plants that should not be treated with antidesiccants?

Yes, some plants should not be treated with antidesiccants. Waxy blue conifers such as blue spruce and blue atlas cedar have a natural protective coating, and a spray can strip that layer and dull their signature color. Also avoid applying them to certain conifers before they are fully dormant. Always follow the product label and consult an arborist.

Do antidesiccants need to be reapplied during winter?

Antidesiccants often need to be reapplied during winter because the protective film gradually breaks down under sunlight and fluctuating temperatures. A single application typically lasts several weeks, so a second treatment in late winter helps maintain coverage through February, when moisture loss from broadleaf evergreens is often at its worst. An arborist can time reapplication to local conditions.

SavATree Suggests Winterizing with Antidesiccants

Antidesiccant sprays can protect plants throughout the winter by helping to reduce water loss…

Winter can be very stressful on trees and shrubs. Extreme temperatures, strong winds, heavy snow and ice storms can all take a toll. The most common threat to plantings during winter is water loss. As the ground freezes, plants are unable to draw up essential moisture so the leaves begin to sacrifice their stored moisture. Additionally, harsh winds blow across the leaves drawing out more moisture potentially leading to sunscald, windburn or, in extreme cases, plant death.

With proper care and the right tools, you can reduce the impact of these harsh elements. The experts at SavATree suggest treating broadleaf evergreens with a natural polymer antidesiccant, such as ArborGuard^TM, SavATree’s exclusive formula. Newly transplanted trees and young trees will also benefit from this treatment.

What are Antidesiccants?

Antidesiccants are compounds that, when applied correctly, slow the loss of water from plants. They work by creating a thin barrier over the leaf stomata (the leaf’s pore) locking in moisture. Antidesiccants are especially beneficial at times when roots are unable to take up sufficient water due to a lack of available ground moisture.

Patrick Parker, Director of Plant Health Care at SavATree advises, “To bolster the defenses of our customers’ trees and shrubs throughout winter, we suggest treating with antidesiccants in late fall/early winter — before temperatures dip below freezing. This will give delicate plantings an added layer of protection.”

What Is Winter Burn?

Winter burn, or winter desiccation, occurs when a plant loses water through its foliage faster than it can replace it. Frozen soil, cold, dry air, and winter wind drive it, and bright winter sun often makes it worse. The damage typically shows up as brown or scorched leaf edges, needle browning or drop, and curled foliage, usually appearing in late winter or early spring.

Injury generally starts before symptoms become visible, and once foliage browns, it does not recover. Preventive treatment before the coldest weather arrives is more effective than reactive spring remedy.

Which Trees and Shrubs Benefit Most?

The plants most susceptible to winter desiccation, and therefore the best candidates for treatment, include:

Broadleaf evergreens such as holly, laurel, boxwood, azalea, and rhododendron
Conifers such as juniper, arborvitae, cypress, pine, and cedar
Newly planted, transplanted, and young trees establishing their root systems
Tender stems, including rose canes and hydrangea stems

Plants in windy, exposed locations tend to see the greatest benefit, since those sites accelerate moisture loss.

Which Plants Should Not Be Treated?

Not every evergreen warrants antidesiccants. Waxy blue conifers such as blue spruce and blue atlas cedar carry a natural protective coating on their needles, and an antidesiccant can strip that layer and dull their signature blue color. Certain conifers should not be sprayed until they are fully dormant, because a coating applied too early can trap moisture that freezes and damages plant tissue. This is one reason professional application matters, and why it helps to have an ISA Certified Arborist assess your landscape before treatment.

Part of a Complete Winter Care Plan

Antidesiccants work best as part of a broader strategy. Deep watering before the ground freezes, a proper layer of mulch to insulate the root zone, and physical barriers in especially exposed areas all work together to help plants through the season. Healthy, well-hydrated plants entering dormancy are more capable of withstanding harsh conditions.

Antidesiccants Provide Year-round Benefits

Even during the growing season, a plant might not be able to keep up with water lost through its leaves and could benefit from this added layer of protection. Learn more about antidesiccants and other ways to protect your trees and shrubs during the winter.