How to Protect Plants From Frost Over the Winter

Keeping your plants alive and thriving in cold weather – and avoiding frost damage – isn’t impossible with adequate preparation in advance, so timing is crucial.

Frost is forecast when temperatures get closer to 32 ° F. But since it is always colder near the ground, frost can occur even at air temperatures just above freezing point.

There are three different degrees of frost, and each one causes different degrees of damage:

  • A light frost (29 ° to 32 ° F) kills delicate plants but has little effect on other vegetation.
  • Moderate frost (25 to 28 ° F) causes widespread destruction of most vegetation with severe damage to amniotic flowers and delicate semi-hard plants.
  • Severe frosts (24 ° F and colder) will cause severe damage to most plants.

Some plants are more sensitive to frost than others. Adult plants are less prone to frost damage than newly planted, young ones.

Those with maroon or bronze colored leaves have a higher tolerance to frost because these leaves absorb and store heat, as do plants with hairy leaves, according to The Old Farmer’s Almanac.

Compact plants are naturally less sensitive to frost, as a smaller proportion of their leaves are exposed to cold and drying winds. Similarly, plants closely spaced also help protect each other.

Here we look at some basic steps to take to protect plants from frost and cold.

Know your frost dates

The US National Weather Service issues frost warnings and frost warnings that you can use to plan how to protect your crops at the beginning or end of the growing season. But these notices / warnings are only useful as long as a hard freeze or killing freeze has taken place, says the NWS.

To prepare your plant for cold weather conditions, find the predicted frost date (the average date of the last light frost in spring or the first light frost in autumn) in your area, which varies across the country.

Frost dates calculated using data from the US National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information are only estimates based on historical climate data, and not set in stone, advises The Old Farmer’s Almanac.

However, this data is useful for getting a head start on preparing your crops for winter.

Ice crystals can be seen on grass.
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Make sure you have enough water

It is important that plants newly planted in the fall are well watered in the winter before the soil freezes.

Speaking to Newsweek, writer and houseplant expert Lisa Eldred Steinkopf said, “This is especially important for evergreen plants. What they have stored is enough for the winter as they cannot absorb water after the ground is frozen. Early spring is also important for watering. “

When the ground is no longer frozen and there has been no significant rainfall, your plants will need watering. Plants, especially evergreens, produce photosynthesis when the soil thaws and need water for this. So it is imperative that your plants be watered when the soil is thawed, advised Eldred Steinkopf.

It is important to water well before a frost, as moist soil can store up to four times more heat than dry soil. This allows the heat to be conducted to the surface of the earth faster and the air above it to be kept about five degrees (Fahrenheit) warmer.

Another way to store heat with water is to leave black-painted milk jugs filled with water in the garden. These jugs absorb heat during the day and give it off at night, the Almanac advises.

Choose the right location

It is also important to choose the right location for your plant before the cold sets in. Plants that need protection from drying winter winds, for example, shouldn’t be placed on the west side of the house, Eldred Steinkopf said.

Strong winds can make frost worse once the temperature drops below freezing, warns Britain’s Royal Horticultural Society (RHS).

Cold winds draw moisture away from evergreen plants faster than it can be replenished, which can cause the leaves to tan at their tips and edges.

Tender plants survive the winter better if they are planted in a sheltered, sunny spot, because “new wood” [stems that develop in the current season] is ripened by the sun, which accumulates more carbohydrates during the growing season, “which makes it more frost-resistant, explains the RHS.

A flower covered in frost.
A flower covered in frost.
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You should avoid planting tender plants in open, exposed areas or in low spots where cold air will settle. It is better to place delicate plant species near a south or west wall, which absorbs heat during the day and radiates it at night.

It’s also worth noting that, according to the almanac, if your plant is “tilted toward the sun,” it warms up more. “Cold air, which is dense and heavy, flows away from plants growing on a slope – what the experts call ‘drainage’.”

Canada’s Department of Agriculture, Food and Rural Affairs for Ontario states that areas near large bodies of water are typically less prone to frost damage because air masses over water cool less quickly at night than over land. In coastal locations, land breezes also frequently occur in the evening, which help avoid frost.

Cover your plants

One of the most common methods of protecting plants is to cover them with a row cover or blanket, which will lock in heat and keep your plants warmer.

Non-woven polyester row covers are sold in a variety of thicknesses or weights. Sheets, towels, or other medium-weight fabrics can also be used to cover plants, but do not use plastic.

Eldred Steinkopf warns against wrapping plants in burlap, a fabric typically made from the skin of the jute plant or in combination with plant fibers.

“Only use canvas trellis in a windy place or if salt gets on your plants. If they are well watered until the soil freezes, there is no need to wrap them. Never let burlap touch the plants, ”she said.

Plants covered for winter protection.
Potted plants covered for protection over the winter.
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The cover should be draped loosely to allow air to circulate and the material should not rest on the plant. It should also be secured to the ground with stones, bricks, or stakes to prevent it from touching the foliage below.

Water your plants lightly before laying the covers over them in the late afternoon or early evening. It is best to put the covers in place well before sunset.

In the morning of the next day, when the temperature rises, remove the covers so that the plants are fully exposed to the sun.

Sometimes an unexpected early frost can occur, so it pays to cover your plants in preparation for this “freak incident,” warns the Almanac.

For smaller plants, you can make “hot caps” by cutting off the top half of empty milk cartons or soda bottles, or by using paper bags or newspapers.

Plants grown in containers should be moved to a sheltered location in cold weather, and the pot can be wrapped in bubble wrap for additional protection.

“In winter, the greatest enemy of plants in pots is permanently wet potting soil. Provide adequate drainage by placing the vessels on the pot feet (or improvising with small stones), ”explains the almanac.

Row cover over plants on a farm.
Row cover hovering over plants on an organic farm.
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… and the floor

You should also cover your soil to protect soil life such as worms, bugs, and fungi that are beneficial to plants. Add a thick layer of organic matter to the soil surface to protect it from erosion and to keep soil life well fed, notes The Old Farmer’s Almanac.

The type of soil you have can affect the chances of your plants being damaged by frost. Deep, loose, heavy soils release more moisture into the air than thin, sandy, nutrient-poor soils. You want to keep the air humid because the more humid the air, the higher the dew point, which reduces the likelihood of freezing on your plants.

Don’t add nitrogen-rich fertilizers late in the season as they “stimulate soft, succulent growth,” which makes plants particularly susceptible to frost damage, says the RHS.

Red chrysanthemums covered with fresh snow.
Red chrysanthemum flowers covered with fresh snow.
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