How to Protect Plants from Cold Weather, Frosts

Once or twice a year, even warm regions like Florida can experience a freeze. Cold weather in a tropical and sub-tropical region can cause extreme damage to landscaping and outdoor potted plants.

When freezing temperatures are expected, gardeners and homeowners must take measures to protect outdoor plants from freezing. Protecting plants from the cold for a short period of time (i.e. a few hours overnight) is fairly simple and it can be done using items found around the house.

Before a freeze, it’s important to determine which tropical plants are cold tolerant. Many tropical plants will die or sustain foliage damage during a frost, while others don’t require any special attention during cold weather. Gardeners should document each plant type in their garden, along with information on which plants will die during a frost or hard freeze.

How to Protect Tropical Plants from Freezing Weather – Watering

The first step to protect tropical plants and palm trees from cold weather involves watering. Gardeners should water all landscape plants at least 24 hours before the predicted freeze.

According to the University of Florida website, “Watering landscape plants before a freeze can help protect plants. A well-watered soil will absorb more solar radiation than dry soil and will re-radiate heat during the night.” Watering plants can help protect the plant from cold in the short term, but gardeners must remember that long term exposure to moist soil can damage some plants.

Misting plants during a period of freezing temperatures can also form a protective layer of ice, which insulates the foliage or fruit. This method is often utilized by farmers, who can protect fruits and vegetables by covering them with a layer of ice!

Covering Plants During a Freeze, Mini-Greenhouses and Cold Frames

For small or young plants, gardeners can create a mini-greenhouse to protect the plant from the cold. Cut the top 1/3 off a soda bottle to create a plastic dome; place the plant inside the dome and sink the edges into the soil. This tiny greenhouse will retain heat, protecting the plant from freezing temperatures.

For larger plants, gardeners can create a cold frame. More permanent cold frames can be constructed out of wood and plexiglass. Other cold frames are made out of PVC pipe and plastic sheeting. Cold frames protect the plants from the cold weather; they operate on the theory of “if you can’t bring the plant to a greenhouse, bring the greenhouse to the plant.”

Even a cardboard box can be turned into a homemade cold frame. The top panel of the box must be cut away to create a window; use plastic sheeting or a few layers of plastic wrap (taped in place) to create the window. Put the box over the plant; it will serve as a makeshift cold frame, protecting the plants from the cold wind and freezing temperatures for a short period of time – this homemade cold frame is perfect for Florida, where it rarely rains during the winter (the cardboard will disintegrate once wet.)

On the day of the freeze, gardeners must cover plants to protect them from the cold (unless they’re protected by a mini-greenhouse or cold frame. Special insulating fabric and frost blankets for plants can be purchased from most nurseries and home improvement stores, but in a pinch sheets and blankets can be used to cover the plants, protecting them from frost and freezing temperatures.

Protecting Palm Trees from a Freeze or Frost

Most palm trees need special protection during a frost or hard freeze. The trunk of the palm tree does not generally require any sort of protection, but the palm tree’s heart must be protected if temperatures reach the freezing mark. If the palm tree’s heart freezes, the tree will die.

The palm tree heart is located at the top of the trunk; it’s the point where all new foliage originates. To protect a palm tree during a frost, fabric should be wrapped around the heart and as much foliage as possible should be covered as well. For many palm tree types, it’s helpful to gather the palms together into one large bunch that can then be wrapped with a string or bungee cord.

For very broad or large palm trees, like the Bismarck palm, pygmy date or triangle palm, an outdoor patio heater can be an effective way to prevent frost damage to the palms and heart.

Protecting Potted Plants from Cold Temperatures

Potted plants are particularly susceptible to cold damage due to the lack of insulation around the roots. Potted plants are often fairly small in size, which also makes them more prone to freezing and frost damage.

In fact, even cold tolerant plants can die during a freeze if they’re potted. The roots of a potted plant tend to freeze very quickly ‚Äî much faster than a plant in the ground ‚Äî leading to irreparable damage, and ultimately, the death of the plant.

For this reason, it’s best to bring potted plants indoors if freezing weather is predicted. For plants that are too large to bring indoors, there are a few options. The plant’s foliage can be covered or wrapped with sheets or blankets and a towel can be wrapped around the pot to prevent root damage. Another option to protect plants from the cold involves relocating them to a garage or shed. If freezing temperatures are expected to last for more than a few hours, space heaters can be used to keep the plants warm while situated in a shed or garage.

Pet owners must take special precautions to protect potted plants from pets that may try to eat the foliage while the plant is indoors. Birds, cats and dogs can die if they ingest certain houseplants, so it’s best to place toxic plants in a room that’s off-limits to pets. If a plant must be kept indoors for an extended period of time, bitter apple spray can be applied to the leaves to prevent pets from eating the leaves. To learn more about what plants are toxic for dogs and cats, read Toxic Plants and Pets.

Florida residents may enjoy other gardening tips in How to Plant a Garden in Florida.