During the transition from summer to fall, one day may be warm and balmy while the next is crisp and clear. As a result, your outdoor plants will likely require some assistance to continue thriving during this changeover. Here’s how to protect your plants from frost.

1. Assess the situation

Before you make any plans for your plants, understand what kind of frost you might be facing. Different lengths of chill will require different actions.

If you’re preparing for a longer duration of cold, you’ll want to gradually ready your plants for the oncoming temperatures. Decrease watering so that the plants can begin to harden for the months ahead. Add a layer of compost, which will continue to feed the soil around the plant during a frost. After the first frost, replace old mulch with heavier evergreen boughs or hay—this will offer a greater level of insulation for the plant in the event of snow.

The following guidelines are for plants facing a shorter cold snap, like overnight freezes that cause hoarfrost when the dew point drops to 32ºF.

2. Create a warm environment

How you create a warm environment depends on the size and shape of the plants that need to be protected.

Ground plants

To protect plants that are low to the ground, take a blanket or sheet and drape it over the entire plant. Make sure the covering reaches the ground so it can trap heat. For added security, you can secure the cover with stakes. Cover the plant before dusk to ensure you contain as much of the day’s natural warmth as possible.

For added protection, use a layer of plastic over the blanket or sheet. However, a plastic covering should never be used alone, and any coverings you apply should be removed early the next morning. If not removed, condensation could accumulate beneath the covering, which would then lead to frost if temperatures dip again. Additionally, allowing your plants to see some sun will support them with the nutrients they need to continue thriving in cold weather.

If you don’t have a blanket or sheet, you can use a cardboard box.

  1. Cut out the bottom of any cardboard box large enough to cover the plant, then tape up the flaps of one end of the box.
  2. Cut along three sides of the top to create a hinged box lid.
  3. Before dusk, place the box over the plant and ensure the hinged lid is closed. During the day, keep the lid open so your plant receives the sunlight it needs.

Taller plants

For taller plants, such as fruit trees, you’ll need a different approach. Essentially, you’ll create a tipi shape using burlap and stakes.

Simply drive three (or four, depending on the size of the plant) stakes into the ground at an angle around the plant. Wrap the burlap around the stakes and secure the burlap with a sturdy string or rope so that it remains closed, creating a warming fence around and over your plant.

If you think your plant could use extra warmth, fill empty plastic milk jugs with warm water and nestle these jugs around the root or trunk of the plant. This will keep the air around the root of the plant—where temperature matters most—warmer for an extended period.

Hanging plants

To best protect hanging plants from frost, bring them inside if at all possible. If this isn’t an option, place hanging plants on the ground and cover with one of the above methods, which will keep them warmer than if they had continued to hang.

How to revive plants damaged by frost

Despite your best efforts, you may wake up to discover that some of your plants have been damaged by frost. If this is the case, there are steps you can take to revive them.

  1. If possible, bring the plant inside the house, placing it out of direct sunlight where it should remain for the first 48 hours, and water the plant immediately. Because frost damage occurs as a result of ice crystals wicking moisture from the leaf tissue (hoarfrost), provide your plant with a healthy amount of water.
  2. Only after the plant has been inside the house for several weeks should you begin to trim dead flowers and leaves. Pruning off the dead foliage will prompt the plant to regrow.
  3. Because regrowth is such an energy-taxing process, give the plant plenty of time to recover from the frost before initiating a phase of regrowth. Otherwise, the regrowth could put your plant under excessive stress, hindering its chance at survival.

If your plant cannot be brought inside to recover from frost, resist the temptation to heavily water or fertilize outdoor plants that have become frost-bitten. Offer them a normal amount of water, and then be patient and wait for new growth to occur. Once the warm weather returns, the damaged parts will likely fall off on their own.


    What Is Extreme Cold Weather?

    A freeze occurs when temperatures drop below 32° F or 0° C. When the water inside a plant freezes, it can cause the plant cells to burst, resulting in irreparable damage.

    Here’s how different plants react to extreme winter weather:

    • Tropical and frost-tender plants: Cannot survive extreme cold so they only grow naturally in warmer climates.
    • Annual plants: Can’t survive extreme cold, but they disperse seeds to replenish their numbers once the weather warms.
    • Root-hardy perennials: The foliage is killed back by a freeze, but the roots survive in a dormant state until spring.
    • Fully hardy perennials, shrubs, and trees: Enter a dormant state, which decreases vulnerability to freezing temperatures by reducing sap content and conserving water. Spring blooms and early foliage may be damaged by late-spring freezes, but the plants themselves usually recover.

    Fragile blossoms are threatened by late spring freezes.

    What Is Frost?

    Frost occurs on clear, still nights. As the air temperature approaches freezing, the surface temperature of plants can dip below freezing, causing ice crystals to form in the same manner that dew forms on warmer nights.

    Because temperatures vary just a few feet above the ground, frost can form when your thermometer reads above freezing. Cold weather may or may not be accompanied by frost.

    Types of frost include:

    • Hoarfrost — the familiar feathery white frost you see on chilly mornings. It results when water in the air is deposited directly in the form of ice crystals.
    • Rime — happens when water is deposited in liquid form through dew or fog, which then freezes. Rime has a glazed appearance.
    • Black frost — a term used when frost didn’t form, but plants were nonetheless damaged (and blackened) by freezing temperatures.

    Effects of Freezing Temperatures on Plants

    For all but the most tender plants, it doesn’t matter whether the conditions produced a frost or a freeze. What’s important is how cold it got and for how long.

    When temperatures near freezing, a few degrees can make a big difference.

    To advise gardeners so they can take proper precautions, different terms are used to describe the severity of a freeze. This chart explains the various terms:

    TemperatureTypeEffect on Plants
    Down to 28° F for a couple of hoursLight Frost,
    Light Freeze
    Usually only harms very tender plants. Ice forms only on the outside of the plant.
    25-28° F for several hoursHard Frost,
    Killing Frost,
    Moderate Freeze
    Damages foliage and blossoms. Ice forms inside the plant, causing plant cells to burst. Will kill back root-hardy perennials and damage crops.
    Below 25° F for several hoursSevere freezeExtremely cold weather causes damage to many plants, mostly through desiccation (drying).

    The average first and last frost dates for a given area usually refer to the occurrence of killing frosts. These are most often caused by fronts of arctic air moving in and are more indicative of seasonal change.

    Research has shown that most crops and plants can recover from brief dips below freezing, but when the temperature reaches 28° F it begins to cause extensive cellular damage and crop loss.


    Further Information

    To find the average frost dates for your area, check out:

    Editorial Contributors
    avatar for Danny Lipford

    Danny Lipford

    Founder

    Danny Lipford is a home improvement expert and television personality who started his remodeling business, Lipford Construction, at the age of 21 in Mobile, Alabama. He gained national recognition as the host of the nationally syndicated television show, Today's Homeowner with Danny Lipford, which started as a small cable show in Mobile. Danny's expertise in home improvement has also led him to be a contributor to popular magazines and websites and the go-to source for advice on everything related to the home. He has made over 200 national television appearances and served as the home improvement expert for CBS's The Early Show and The Weather Channel for over a decade. Danny is also the founder of 3 Echoes Content Studio, TodaysHomeowner.com, and Checking In With Chelsea, a décor and lifestyle blog.

    Learn More

    photo of Lora Novak

    Lora Novak

    Senior Editor

    Lora Novak meticulously proofreads and edits all commercial content for Today’s Homeowner to guarantee that it contains the most up-to-date information. Lora brings over 12 years of writing, editing, and digital marketing expertise. She’s worked on thousands of articles related to heating, air conditioning, ventilation, roofing, plumbing, lawn/garden, pest control, insurance, and other general homeownership topics.

    Learn More