Winter can be a dry time for your skin, and it can dry out plants, too. With less humidity in the air, plants can lose moisture from their leaves faster than they can replace it.
“Plants that lose too much water can die, and anti-desiccants create a protective film on the plants to reduce the amount of water lost through transpiration,” says Hannah Shaw, regional inventory manager with SiteOne.
Anti-desiccants, also known as anti-transpirants, inhibit transpiration, the process where plants lose water through their foliage.
“The most frequent use of anti-desiccants is to prevent winter burn and dieback due to rapid temperature fluctuations,” Shaw says. “They can help shield plants against prevailing winter winds and protect sensitive plant species from the cold.”
Anti-desiccants are also helpful in protecting against shock during transportation or transplanting.
Rules of Thumb for Usage
Anti-desiccants can be used on numerous species, but they are most commonly applied to conifers, broadleaf evergreens, roses, and hydrangeas, which are most susceptible to winter desiccation.
Shaw says while this type of product is very useful, it’s essential to apply them properly to prevent damage caused by improper applications.
“Always remember that timing is important,” Shaw says. “If you are using them in preparation for winter, do not apply them too early. It’s crucial to wait until the plants have hardened off and gone dormant before applying anti-desiccants.”
If coniferous trees or shrubs are treated before they have fully hardened off, Shaw says they will suffer.
It’s also important not to apply anti-desiccants if they don’t have enough time to dry before freezing temperatures. Shaw says anti-desiccants that are still wet when the temperature dips below freezing can damage or kill plant cells.
“Even though anti-desiccants can help plants buffer cold temperatures, they cannot protect plants from internal ice crystal formation,” Shaw says.
Because drying times can range from four to 24 hours depending on the formulation, Shaw advises always following the label instructions about drying times.
Common Mistakes
Shaw says the biggest mistake is when users don’t read the label thoroughly for an anti-desiccant.
“Anti-desiccant labels will list which plant species to not apply to, give guidelines for the best timing of application, and the types of nursery stock the product will work best with,” Shaw says.
For example, some anti-desiccants may strip blue colorations from some plants.
“Anti-desiccants can strip away the natural, protective epicuticular wax on species like Blue Spruce (Picea pungens) and Blue Atlas Cedar (Cedrus altantica ‘Glauca’),” Shaw says. “Loss of this waxy coating destroys their attractive blueish hues. Also, anti-desiccants should not be applied to any plants with tomentose or hairy foliage.”
Another common mistake is only applying anti-desiccants once and not reapplying them according to the label.
“Once applied, these products can last from one to four months depending on the time of year, environmental factors, application techniques and which specific anti-desiccant is used,” Shaw says. “Typically, they last up to two months during the growing season and up to four months in the dormant season.”
It’s also critical to completely coat the plant and avoid leaving exposed areas.
Additional Advice
Shaw suggests identifying your objectives prior to making an application.
“If spraying in winter, wait until the plants have hardened off or are dormant,” Shaw says. “Ensure thorough coverage of the entire plant. Check the weather forecast prior to application to avoid rainfall or freeze before the product has dried. Always read the label; not all anti-desiccants are the same.”
Also, consider all the tools in your toolbox to help manage desiccation in plants. Cultural and physical barriers can be useful alone or in combination with anti-desiccants.
Materials like burlap, frost cloth and mulching can help with temperature buffering. Also, adequate watering prior to the plant going dormant can reduce excessive drying.
“Combined with anti-desiccants, these are all effective methods to protect plants during the cold winter months,” Shaw says.
