Have you noticed carrots, kale, or broccoli taste better after a frost? That’s because some cool-tolerant veggies convert their starches into sugars as temperatures drop. Discover how this natural sweetness develops and which crops to keep growing for a more flavorful harvest.
If you want to venture into more cold weather growing, also see How to Grow Vegetables Outdoors in Winter.
Vegetables That Sweeten With Cooler Temperatures
- Beets
- Broccoli
- Brussels sprouts
- Cabbage
- Carrots
- Cauliflower
- Celeriac
- Collard greens
- Kale
- Leeks
- Leafy greens (some)
- Parsnips
- Radishes
- Rutabagas
- Swiss chard
- Turnips
If you have ever delayed harvesting vegetables in autumn, you probably already know many vegetables are not only fine to pick after a frost but taste even better.
For many veggies, so long as they didn’t freeze, the cool temperatures have improved the sweetness.
Carrots and beets are a classic example.
I first noticed this with homegrown Brussels sprouts. I had a bunch that were under-sized, so, instead of harvesting them in fall, I left them in the garden.
During a late-winter thaw, I finally picked them and roasted them in the oven (with olive oil and salt—yum!). That is next level flavor. The sugars—thanks to the frosts—caramelize as they roast and it is delicious.
If you are a veggie eater but have never acquired a taste for Brussels sprouts or the other vegetables listed, this is the key—hold off harvesting until you’ve had some frosts!
How Vegetables Become Sweeter with Frost
As you can see by the list (above), not all vegetables get better with cold conditions.
First, the vegetable needs to be cool-tolerant (not tender) and the fruit (edible part) needs to be mature when the frosts set in.
Tomatoes and other warmth-lovers are sensitive to frost and will freeze and die rather than adapt. Thankfully you can ripen some green tomatoes after picking.
But the cool weather vegetables are going to improve with the cold.
How It Works
- The sweetness of vegetables comes from their sugar content.
The sweetness of vegetables comes from their sugar content.
Plants create sugars through photosynthesis.
Carbon dioxide is taken from the air, water from the soil, and, powered by sunlight, create sugars.
That sugar is often stored as starch, which is essentially a long chain of glucose.
Even though starch doesn’t taste sweet, that’s really what it is, a big chain of sugar.
- When plants experience frost or cold temperatures, that’s a threat.
When plants experience frost or cold temperatures, that’s a threat.
Ice can form within the plant, in its cells, leading to dehydration and other dangers.
To defend themselves, plants have developed various responses as part of their acclimation or cold hardening processes, and one of those is to free up some of those sugars stored as starch.
Sugar helps defend against frost damage: these plants will accumulate sugar in response to cold stress.
And, unlike starch, the sugar does taste sweet.
Does growing vegetables in cold weather guarantee sweetness?
No. Whether you notice the difference will depend on the vegetable’s traits, your taste buds, and how much sugar has accumulated.
But the odds are, you will enjoy a boost in sweetness.
So, no worries if you didn’t clear out your vegetable garden in fall. You might just find your best harvest ever.
Resources
Listen
Year-Round Vegetable Growing
I was first introduced to cold-weather vegetable gardening when I read Niki Jabbour’s book, The Year-Round Vegetable Gardener.
The Year-Round Vegetable Gardener
by Niki Jabbour
Niki lives in Nova Scotia, Canada and grows vegetables year-round.
Find out how to plant, what to use to keep your crops protected, and how to keep harvesting veggies even in a cold climate all year long.
See More
How to Grow Vegetables Outdoors in Winter (in Canada!)
The goal is to keep your fall and winter veggies protected with covers or cold frames so they can chill without freezing.
If you are new to the idea, it’s a great resource for getting started.
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