A lot of people who are new to gardening in Middle Tennessee don’t realize we can grow veggies into the fall and winter. One of the joys of gardening here is (no, not the humidity and mosquitoes) that we can easily harvest 10 months out of the year. The trick is planting the right plants at the right time, and understanding which veggies can survive when it gets cold. Let’s break down the frost tolerance of common garden plants so you know what to expect in the colder months ahead.

What do we mean by “frost?”

In gardening, "frost" refers to a weather condition where the temperature drops to 32°F (0°C) or below, causing the moisture in the air or on plants to freeze. This can harm or kill certain plants, particularly those that are not frost-tolerant. As the moisture inside the plant cells freezes and expands, it ruptures their cell walls. Frost typically occurs during clear, calm nights when the heat from the ground radiates into the atmosphere, cooling the air near the surface to freezing levels.

There are different types of frost:

Light Frost: Occurs when temperatures are just at or slightly below freezing, usually between 29°F to 32°F. Some frost-tolerant plants can survive this.
Hard Frost: Happens when temperatures drop below 28°F, causing more severe damage to tender plants.

When it is coming? There is no way to predict exactly, but we look at the historical weather data to make our best guess. In middle Tennessee there is a 50 chance we will get our first frost by October 29.

Frost-Sensitive Plants: Their Days are Numbered

Some of your garden favorites, especially warm-season crops, can’t handle frost and will likely die when temperatures drop. These plants need to be harvested or protected before the frost hits, so watch the forecast like a hawk as we approach the end of October.

Tomatoes: As one of the most popular garden veggies, tomatoes are not frost-tolerant. Even a light frost can damage the leaves and fruit, leaving you with mushy, unripe tomatoes. If a hard frost is in the forecast, harvest all your tomatoes. Even partially ripe tomatoes will turn red on your countertop, and green tomatoes make great pickles!
Peppers: Like tomatoes, both sweet and hot peppers are highly sensitive to frost. Be sure to harvest any mature peppers before the first frost date in your area. For extra credit, dig up your pepper, prune it back hard, put it in a pot and treat it like a house plant for the winter. You can plant it back in the garden next spring!
Basil: Basil is extremely sensitive to cold. Temperatures below 40°F can cause blackened leaves and damage the plant, so it’s best to harvest or bring it indoors before the frost arrives.
Cucumbers, Beans, Squash, Okra, and Eggplant: These heat-loving plants will also perish when frost arrives. Plan to harvest or protect them early to avoid loss.

For these sensitive plants, you can use row covers or bring containers indoors if a light frost is forecasted. In our area, we often get a light frost and then enjoy a couple more weeks of mild temperatures, so it’s sometimes worth it to try to protect these plants if temps are only dropping a couple degrees below freezing. However, once temperatures drop consistently, it’s the end of the season for these crops.

Frost-Tolerant Plants: Thriving in the Cold

On the other hand, many cool-season crops can handle—and even thrive—in frost. Some veggies can continue growing after light frosts and even improve in flavor with a touch of frost.

Lettuce: Lettuce is a frost-hardy plant that can withstand cooler temperatures. In fact, a light frost can give lettuce a slightly sweeter taste!
Kale and Swiss Chard: Kale is one of the champions of frost tolerance. These plants not only survives frosty nights but also becomes sweeter after exposure to cold.
Spinach, Broccoli, and Brussels Sprouts: These hardy crops love cooler weather and can easily survive light frosts. Brussels sprouts, in particular, are known to taste even better after frost.
Carrots and Beets: Carrots are frost-tolerant, and their flavor improves after exposure to cold. The cooler temperatures cause the roots to become sweeter and more tender.

Flowers: Protect or Let Them Go?

Many gardeners love to incorporate flowers into their vegetable beds or nearby borders. Here's how some common flowers react to frost:

Marigolds: Marigolds are not frost-tolerant. These annuals will be killed by the first frost, but they’re easy to remove and compost after they’ve died back.
Zinnias: Zinnias, another warm-season annual, will also die with the first frost. Be sure to collect any seeds if you want to save them for next year.
Pansies and Violas: These hardy flowers thrive in cooler temperatures and can survive light frosts. In fact, pansies often bloom well into the winter in mild climates, adding color to your garden when most other flowers have died back.
Calendula, Poppies, Snapdragons, Pincushion Flower, and other “Hardy Annuals”: While these flowers don’t generally bloom during winter, when planted in late summer, they develop green growth and establish strong roots so they are ready to take off and provide early color next spring. So leave them in place over the winter, even though their leaves may look a bit rough. You can groom them up when they start to grow again in spring.

How Can You Protect Your Plants?

While frost-sensitive plants will need protection, frost-tolerant plants don’t require much help to thrive in cooler weather. However, when temps are extra cold (below 25) in January and early February, there are a few steps you can take to extend your growing season:

Use Row Covers or Frost Blankets: For tender plants, row covers can provide a few degrees of warmth. Even for frost-hardy crops, covers can offer extra protection during sudden cold snaps.
Mulch Your Plants: A thick layer of mulch can help protect the roots of frost-tolerant plants and keep the soil temperature more consistent.
Cold Frames or Hoop Houses: These structures can give both tender and hardy crops a longer growing season, protecting them from early frosts and keeping them productive into late fall.

The Final Countdown

There is no way of knowing exactly when our first frost will come, but understanding which plants are frost-tolerant and which aren’t can help you plan your fall garden more effectively. By giving frost-sensitive plants a little extra care and planting some veggies thrive in colder weather, you can enjoy your garden harvest well into the cooler months.

So, will your plants die when frost comes? For tomatoes, peppers, eggplant, okra, and basil, unfortunately, yes. But with crops like kale, lettuce, carrots, and beets, you may find that frost is just what they need to shine.

Q&A: These plants are all about to die when temps go below freezing, right?