The Science Behind the Sweetness – Gardening in Cold Climates
by Stacey Tress

I wonder what the projections are for first frost dates here in the Yorkton and surrounding area; this is my inspiration for this article. We had a late start to the growing season here, due to heavy June moisture and cold soil temperatures. According to the Canadian Hardiness Zones map, Yorkton is 2b, with 3b microclimates. Another plant hardiness map has Yorkton fully as zone 3b, which really has to do with the average cold temps and length of growing season. We are definitely classified as a cold climate, and can use this in our favour when it comes to many vegetables. Essentially, the cool weather unlocks a hidden superpower in root vegetables. As temperatures fall to 32–40°F (0–5°C), they trigger cold sweetening, a survival strategy that converts starches into sugars. These sugars protect plant cells from freezing like a natural antifreeze, while also giving carrots, parsnips, beets, and turnips their irresistible winter sweetness. 

There’s another sweetening called cold acclimation. The sweetness also doesn’t happen by accident. As the days shorten and the nights turn colder, hardy vegetables know winter is on its way. They begin a remarkable survival process also referred to as hardening. This application again, is perfect for cold climate gardening, but not just for root vegetables; includes cold hardy vegetables like kale, bok choy, Brussels sprouts, spinach, and parsley. 

One of the first changes happens at the cellular level. The plants build thicker, stronger cell walls with less water inside each cell. While moisture between the cells can freeze, the cells themselves are much better protected. That means they can keep doing their job—even when temperatures hover around, or below freezing.

Believe it or not, your vegetables are still alive and working through the cold. They’re still carrying out photosynthesis and respiration, just at a slower pace. While the rest of the garden looks like it’s gone to sleep, hardy crops like carrots, parsnips, kale, cabbage, Brussels sprouts, and broccoli are quietly preparing for winter.

Their secret weapon? Sugar.

During photosynthesis, plants use sunlight, water, and carbon dioxide to make starch, their stored source of energy. As cold weather settles in, enzymes begin converting more of that starch into sugar. That’s why root vegetables harvested after a few frosty nights often taste noticeably sweeter than those pulled from warm summer soil.

But the sugar isn’t there just for our taste buds—it’s there to help the plant survive. Those extra sugars act like a natural antifreeze, lowering the amount of ice that forms inside the cells and protecting delicate cell membranes from freezing damage. They also provide the energy plants need to keep functioning through the cold.

You can actually see these defenses at work. Kale leaves may curl, Brussels sprout’s leaves may droop, and broccoli can look like it’s had enough. But these aren’t signs the plants are dying—they’re protective responses. Give them a milder day, and they’ll often perk right back up, thanks to the sugars and other changes that helped them weather the cold. I personally haven’t left broccoli that long to find out, but this works very well with Swiss chard.

As winter settles in, growth naturally slows. The plants shift their energy away from producing lots of new leaves, and instead focus on surviving until spring. Even though they aren’t growing as quickly, they’re still busy underground and inside every cell, producing and storing the sugars that keep them alive—and make every harvest a little sweeter.

Utilizing nature as a root cellar/fridge of sorts, not only extends the growing season for us, but also can store cold hardy vegetables right where they are grown. I’ve heard of folks keeping carrots deep into winter with straw overtops and covered with a hoop-house/garden tunnel. 

We really are an adaptable bunch of gardeners here in the Prairies, and I’ve found some of the most pleasant growing times are the later summer into fall months. (And by most pleasant I mean, mitigated risk of flooding, hail, extreme winds, droughts.)

Recipes

I taught a workshop on Sourdough and Sprouting back in April; included a light lunch. I served up Roasted Carrot Soup. It was inspired by this recipe from the Rodale Cookbook:

Cream of Carrot Soup

1 onion, diced
3 tbsp olive oil
1 lb carrots (5–6 large) unpeeled, thinly sliced
4 cups vegetable stock, or water
1 cup skim milk powder
2 cups cool stock, or water
Salt, white pepper, to taste
Chopped fresh dill, or parsley, for garnish

1. Saute onion in oil until transparent. Lift out of pan and put into blender.
   
2. In same pan, saute carrots until tender. Set aside 1/3 of the carrots. Put 2/3 of sauteed carrots in blender. Add some of the stock or water and puree. Heat in the top of a double boiler.
   
3. Combine skim milk powder with cool stock, using a wire whisk. Add to puree. Add salt and pepper to taste.
   
4. Add the reserved 1/3 sauteed carrots to the soup. Garnish with dill or parsley.

Yield: Approximately 6–8 cups

Ok, so in my version I roasted the carrots, onion, celery, (drizzled with olive oil and sprinkled with dried thyme, paprika), in the oven. I had already roasted a few heads of garlic, so I’ll get to how I used those shortly. The blender I used was a Vita-Mix and once everything was roasted, just added to blender to puree, along with a good 6–7 cloves roasted garlic; thinning with chicken stock, as I went. Dumped everything into a soup pot and continued to thin until right thickness. Brought everything to a low boil, until ready to simmer. Salt/pepper to taste. Oh—I added about a cup of orange lentils (rinsed) to the pot and used a hand blender after about 20 min to mush them into the soup once cooked. The soup was actually pretty amazing—especially with a fat slice of fresh sourdough bread with butter. 

Carrots are pretty versatile and can peak culinary interest. So can beets. Both are used in soups, can be pureed, made into something sweet, pickled, added to salad, roasted—the list goes on and on. Usually my mind goes to a roasted beet brownie—it’s pretty fantastic. I was looking through some of my cookbooks and came across a recipe under Sweet Vegetable Pies called Beet Pie (there was also one in there called Carrot Parsnip Pie).

Beet Pie

2 lbs fresh beets
½ tsp freshly grated nutmeg
1 ¼ cups heavy cream
1 ¼ cups milk
½ vanilla bean
½ cup sugar
3 whole eggs, plus 3 egg yolks, lightly beaten
2 unbaked 10 ½ inch Pate Brisee pie shell, well chilled

Cut the tops off the beets, leaving 1 inch of stem. Wash the beets, put the into a large pot, cover with water, and bring to a boil. Cook the beets, covered, until they are tender, adding more boiling water as needed. Remove the cooked beets from the water and let cool.

When the beets are cool enough to handle, slip off the skins and coarsely grate them by hand, or in a food processor. Stir in the nutmeg and set aside.

Preheat oven to 350º F.

Combine the cream, milk, and vanilla bean in a heavy saucepan, and let simmer for 5 minutes. Remove the vanilla bean.

Using an electric mixer, beat the sugar with the eggs and egg yolks until light and fluffy. Gradually add the hot cream-milk mixture, beating constantly. Strain the mixture into a large mixing bowl and stir in the grated beets, mixing well. Pour into the pie shell and bake for approximately 55 to 60 minutes, until the filling is set, and the pastry evenly browned. Let cool a bit before cutting. Serve warm, or at room temperature.

Beet Horseradish Dipping Sauce

Makes 2 cups

Beet horseradish, a mixture of grated beets and prepared white horseradish, is commonly available and gives this dipping sauce its delicate pink colour. Serve it with blanched sugar snap peas.

2 tbsp beet horseradish
1 tsp prepared horseradish
2 cups creme fraiche
1 tbsp finely chopped fresh dill
1 tbsp chopped scallion

In a medium bowl, mix the beet horseradish, plain horseradish, creme fraiche, dill, scallion, and salt. Refrigerate until ready to use. 

Creme Fraiche

Makes 2 cups

Creme fraiche can be kept in the refrigerator for 2 to 3 weeks.

2 cups heavy cream
2 tbsp buttermilk, or sour cream

Heat the cream over low heat to 100º F. Add the buttermilk and mix well. Put in a covered jar and let sit at room temperature for 6 to 8 hours. Refrigerate at least 24 hours before using.

References

Bane, P. (2012). The Permaculture Handbook: Garden farming for town and country. New Society Publishers. 

Baessler, L. (2021, April 26). Why Do Root Vegetables Get Sweeter with Cold? Learn about winter sweetening of root crops. Gardening Know How. www.gardeningknowhow.com

Thorness, B. (2015, January). Sweeter after a Frost: How winter veggies conquer the cold. Edible Seattle. https://edibleseattle.com

Albright, N. (1973). The Rodale Cookbook. Rodale Press. Cream of Carrot Soup.

Stewart, M. (1995). The Martha Stewart Cookbook: Collected recipes for every day. Clarkson Potter. Beet Pie, Beet Horseradish Dipping Sauce, and Creme Fraiche.

Stacey Tress lives in Rhein, SK, with her husband and two daughters. Owner of Garden Therapy Yorkton, which offers active fermentation kits for purchase (Kombucha, Sourdough, Water Kefir), and fermentation workshops. She is a Holistic Nutritional Therapist (HNT), Young Living Essential Oils Member (#2282633), Permaculture Educator, and holds a Payroll Compliance Professional Designation. To learn more, call 306-641-4239, email: stacey.gardentherapy@gmail.com, www.gardentherapyyorkton.ca, or on Facebook, “Garden Therapy Yorkton.” Also see the display ad on page 9 of the 32.3 Fall 2026 issue of the WHOLifE Journal.