Plants Can Be Sensitive to a Frosty Reception

When it’s cold outside, don’t think your plants don’t notice. Tropical and tender plants such as bougainvillea, hibiscus, avocado, banana, brugmansia, fuchsia, impatiens, plumeria, citrus and gardenias damage easily when the temperatures dip.

“Although really cold nights aren’t usually a problem in Southern California, it’s been freezing quite a bit lately,” said Brent Kittle, owner of Plant Depot in San Juan Capistrano. “We haven’t seen frost like this since 1990.”

Frost damage varies, depending on the severity, from browned leaves to an overall collapse of the plant.

“Some plants like impatiens almost look as if they’ve melted,” says Kittle. “The leaves on other plants brown and fall off.”

More serious frost damage can affect plant tissue and even kill a plant, although many plants hit by frost will seal off damage, leaving only parts of the plant dead. Plants often grow normally in the spring, while some only partially grow back. Young plants and new growth are most susceptible.

Although frost-sensitive plants will always be in jeopardy during the cold months, there are ways you can help them make it through winter.

- Keep plants well watered. When frost hits tender plants, it does its damage by dehydrating them. Plants kept adequately moist stand a much better chance of surviving a frost. Remember that extra watering is usually required after Santa Ana winds.

- Use an anti-transpirant. These products cut down on a plant’s water loss through the leaves. They are applied to the leaf surface.

- Protect plants. Create a protective tent over a susceptible plant. To do so, you must surround it without touching any of the plant parts, because any parts that touch the surface of the covering will be in contact with outside temperatures and can sustain damage.

When possible, create a tent around a plant with a large box or make a frame with poles or PVC pipe that you can then cover with horticultural plastic or bed sheets. Remove covering promptly the next morning.

- Move containerized plants. Potted plants can easily be removed from harm’s way when frost threatens by putting them in a more protected location such as under a tree or beneath a roof eave or patio cover. The closer to the house you can place potted plants the better, because heat emanates from the house.

Clustering tender potted plants is also helpful, as they create a warmer atmosphere when bunched together.

- Choose your planting location wisely. Never place a frost-sensitive plant in the lowest area of the yard, as this tends to be the coldest spot. And pay careful attention to exposure. Choose a south, southeast or western location. Eastern and northern areas of the yard are colder during winter months.

- Spray the plants. Sometimes spraying plants with a constant stream of water will prevent them from freezing during the night, although this can be costly, and can cause other problems like mildew.

- Leave frost-damaged plants alone until spring. No matter how bad it looks, the dead foliage covering a plant is acting like a blanket of insulation and is protecting the roots of the plant.

Don’t prune back the dead parts, as this will break the plant’s dormancy, causing it to re-sprout and leaving it open to more damage. Once the temperatures rise, the plant will break dormancy naturally and begin growing, and you will know exactly what areas are dead and should be removed.

The larger the plant, the longer you’ll have to wait. With many trees, you won’t know the extent of the damage until summer.