Knowledge from Olle Garden Bed: Is it Safe to Eat Vegetables in Your Garden After a Frost?

Autumn is in the air. Gardens are slowing down, and both days and nights are getting cooler. Before you know it, you'll be reaching for your sweaters. The following content also has some reference value for raised garden beds.

Unfortunately, due to changing weather patterns each year, venturing into sweater weather might catch gardeners off guard. So, what do you do when you wake up to a chilly garden? Can you harvest and eat those vegetables?

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Frost Dates

I don't know about you, but I've given up on reliable first and last frost dates. In the past few years, nature seems to have stopped playing by the rules. (Of course, they weren't her rules to begin with. Those first and last frost dates just kept appearing farther from the expected dates, making it more challenging for you to know when to protect your garden.

It's important to remember that regional frost dates are just estimates.

The NOAA reviews data from past years and averages these numbers to estimate when you can expect the first and last frost in an area. Unfortunately, weather patterns have seemed to change even more rapidly in the past few years, making these guesses a bit unreliable.

Chances are that the first frost this year might catch you off guard, either because it's much earlier than expected, or because you've given up on keeping an eye on it. Either way, when you're caught off guard, and you wake up to a garden covered in frost-kissed vegetables, all is not lost.

Don't Panic - Assess the Damage

While even a light frost can kill some plants, it's essential to remember that, if you act quickly, you can usually still harvest and eat the vegetables.

You'll need to assess the damage to determine which veggies are edible and which ones will go into the compost bin. Wait until later in the day to do this assessment. By this time, the plants will have warmed up and rebounded, making it easier to determine the extent of frost damage, if any.

What is Frost Damage?

When frost occurs, the water inside the plant freezes, and sharp ice crystals puncture the plant's cell walls. As the ice crystals melt, the cells collapse, leaving you with mushy vegetables that will soon rot. On the other hand, sometimes the primary plants will die, but the fruit is okay. However, because the plant no longer provides water and nutrients to the fruit, it may rot if not picked promptly. You might find that some veggies on the same plant are fine while others are damaged beyond edibility.

Which Plants are More Vulnerable?

Keep in mind that the higher the water content in vegetables, the more likely they are to turn mushy once the frost melts with the morning sun. On the other hand, more fibrous veggies tend to handle frost better because their fiber cells are harder to puncture with ice crystals.

Some veggies even become sweeter with a few frosts. Nearly all solanaceous crops have high water content; even a light frost can kill them. Tomatoes, peppers, and eggplants are easy targets for light frost. Some cucurbits, such as summer squash, cucumbers, and cantaloupes, are also susceptible. However, you might pick and eat some veggies if the plants are the first to be damaged.

Leafy greens like lettuce and spinach typically pair well with light frosts, though a hard frost will kill them entirely. Similarly, check these plants in the afternoon, as they might look wilted in the morning but perk up later in the day.

When checking for frost damage on your vegetables, look for severe discoloration and mushiness.

These you'll want to put in the compost heap. They've suffered too much damage to be of any use. However, one or two minor blemishes can be easily trimmed off. Or, if you harvest and consume slightly softened vegetables immediately, they might still be quite enjoyable. Typically, by appearance alone, you can determine in the afternoon whether your vegetables are still good to eat.

Enjoy Some Sweet, Frost-Kissed Brassicas

While discussing eating frost-damaged vegetables, it's best to keep in mind that not all frost is bad. In fact, brassicas improve their flavor with one or two frosts. Frosts help concentrate the sugar in these vegetables, making them sweeter. Kale, Brussels sprouts, and many other plants benefit from frosty nights.

Harvest and Store Immediately

When talking about eating frost-damaged veggies, it's a good idea to keep in mind that not all frost is a bad thing. In fact, brassicas improve their flavor with one or two frosts. The frosts help concentrate the sugar in these vegetables, making them sweeter. Kale, Brussels sprouts, and many other plants benefit from frosty nights.

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Keep an Eye on the Forecast

It's a good idea to know your first expected frost date, even if it seems to be shifting. Typically, there's a two to three-week buffer around that date, so you can start taking precautions within that window.

As fall progresses, keep an eye on extended weather forecasts for your local area to know when nighttime temperatures are expected to dip to the freezing range.

If you use a weather-tracking app on your phone, check if it has settings to notify you when frost is expected in your area.

Make sure you have a plan in place well before the first anticipated frost date.