When Does The 1st Killing Frost Usually Occur: How To Save Your Plants

ACROSS AMERICA — The arrival of fall and the approach of the inevitable first killing frost of the season mean ornamental plants and produce gardens are short-lived in much of the country.

To get as much life as possible out of plants, know the average date of the first frost where you live, according to The Old Farmer’s Almanac, a time-tested publication offering a blend of long-range weather predictions mixed with humor and advice on gardening, cooking, fishing, conservation and other topics.

With its by-ZIP-code search tool, Old Farmer’s Almanac makes it easy for gardeners to figure out when they’re most likely to start losing plants to frost.

In a light freeze of 29 to 32 degrees Fahrenheit, tender plants are killed. A moderate freeze, which occurs when temperatures dip to 25 to 28 degrees, causes more damage. Most garden plants can’t survive a severe freeze, which occurs at 24 degrees. and colder, according to The Old Farmer’s Almanac.

It’s a good idea for gardeners to keep a close eye on weather forecasts now if they want to squeeze more life out of their plants (of course, many people are over their gardens and ready to move on to something else). The average date of the first frost is an estimate based on historical climate data from the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information. The probability of a frost occurring before the first frost date is around 30 percent.

You may be able to extend the life of plants by protecting them when overnight temperatures dip into the frost-danger zone. Some early fall favorites, such as pumpkins, tomatoes, sweet corn, watermelon and others, can be damaged at 33 degrees, according to the publication.

The best way to protect plants from frost is to cover them with a blanket, bedsheet or some type of row cover. Drape them loosely over the plants, and anchor with them with bricks or rocks.

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If you know a frost is coming, harvest as many vegetables as possible. Tomatoes, cantaloupe and a few other fruits will continue to ripen after they’re picked, but others, like bell peppers or eggplants, can only mature on the vine.

The Old Farmer’s Almanac has more tips, as well as a vegetable-specific guide to frost dates.

Bring Some Ornamentals Inside

If you invested in hibiscus and other tropical plants, Boston ferns, geraniums and others plants for your deck or patio, these ornamentals and herbs can overwinter inside. If you plan to do this, don’t wait for the first frost.

The Old Farmer’s Almanac spells out what to do — it depends on the variety of plant — but in general, give them as much light and humidity as possible, keep them away from heat ducts and expose them to artificial light if necessary.

Regardless of the plant, you’ll want to check for aphids and other insects. Spraying a 1 percent solution of Dawn dishwashing detergent (original) can do the trick. For best results, mix 2½ tablespoons of detergent in 1 gallon of water.

Bulbs, tubers and corms, such as cannas, dahlias and some lilies, can overwinter in the basement or garage. Just cut back the foliage, gently dig up the bulb and store the dried roots in a cool, dark spot, such as a basement.