The main cause of winter damage to trees and shrubs is through dessication, or drying out. When the ground freezes, plant roots are unable to take up water from the soil, so they quickly begin to use up all the water stored in their leaves and stems. This is very damaging, particularly to evergreen trees and shrubs that don’t protect themselves by dropping their leaves in winter.
Anti-desiccants are products that can be applied to evergreen trees and shrubs to help hold in moisture through the winter. If you have problems with cold damage in your garden, you may want to give them a try.
What Are Anti-Desiccants?
Anti-desiccants, also called anti-transpirants, are sprays that provide a protective coating to evergreen foliage that reduces the amount of water that escapes. Anti-desiccants such as Moisturin are made of chemical polymers, and products such as Wilt Pruf are made from pine oil.
Anti-desiccants are gradually washed and worn away over several months, so by springtime they’re gone. While all anti-desiccants are marketed as biodegradable, the ones with the most natural ingredients will be the safest for you and your plants.
In areas with harsh winters, anti-desiccants are applied twice, in November/December and again in February. In areas with more moderate winters, one application in December or January should see you through the coldest months.
How to Use Anti-Desiccants
Anti-dessicants are most often used on:
- Broadleaf evergreens such as azalea, boxwood, holly, and rhododendron.
- Conifers such as arborvitae, cedar, cypress, juniper, and pine.
- Tender stems such as rose canes and hydrangea stems.
Caution: Don’t spray waxy-blue conifers such as blue spruce – they already have a natural coating that you don’t want to damage.
Follow all package instructions with your anti-desiccant, and also keep in mind these tips:
Pick a Nice Day: Anti-desiccants are best applied when temperatures are in the 40s-50s, with no rain forecast for a few days. Foliage needs to be dry when applied, and the spray needs time to dry afterward.
Don’t Spray too Early: Wait until at least December to spray conifers, because these plants can be damaged if you apply the anti-desiccant too early. These plants must be completely dormant (which involves moving water down to the roots) before applying, or else the spray will trap water in the leaves that will freeze and burst the plant cells later.
Spray Thoroughly: Plants lose water from both the tops and bottoms of the leaves. Be sure to spray the plant completely!
Other Uses for Anti-Desiccants
If you have spray left over, hang on to it. Anti-desiccants can also be used for:
- Bulbs: You can apply an anti-desiccant to tender bulbs before storing.
- Transplanting: If you find yourself transplanting a stressed shrub in midsummer, an anti-desiccant can help hold in moisture until the plants put out new roots.
- Pumpkins: Apply anti-desiccant to your carved jack o’lantern to help it last longer.
- Christmas Trees: Anti-desiccant can help keep your cut Christmas tree from drying out as fast.
- How to Protect Your Garden from Frost and Freeze (article)
- When to Water Plants Before a Freeze (article)
- Planting Trees and Shrubs in Late Fall or Winter (article)
- How to Store Tender Bulbs Over the Winter (article)