15 Cold-Season Vegetables That Get Sweeter After a Frost

When people tell me that they enjoy eating spring carrots or kale, I can’t help but tell them to wait until the fall. Sure, spring and summer crops are great, but cool temperatures lead to supremely sweet vegetables. That means if you give me the option of spring or fall roots and greens, I’ll choose fall-grown veggies every time.

You may have heard that frost leads to sweeter veggies. And that’s partially true. It’s not exactly the frost that causes plants to concentrate their sugars, but rather the cold temperatures accompanying these shining crystals. 

When plants sense cold temperatures, they concentrate simple sugars in their cells. This process prevents plant cells from freezing and bursting, which allows the plants to survive into the winter. Studies show that this concentration of sugars occurs in roots and leafy greens.

If you want to capitalize on the sweetness that cold temperatures cause, you can grow many cold-season roots and greens. The following vegetables are all sweeter after a frost.

Carrots

Carrots can survive a light to medium frost, and they will be sweeter for it! Cold temperatures cause the plants to concentrate sugars in their roots, leading to sweet and crunchy carrots that some of my customers have described as “carrot candy.”

Remember that most carrots take two to three months to grow from seeds into fat roots, so plant your carrot seeds well before the first frost arrives. I like to plant carrots in August for an October or November harvest. Poor germination is one of the most common problems gardeners face when growing carrots, so keep the soil moist during hot August days.

Hard frosts may cause carrot greens to die back, but the roots will remain safe and insulated by the cool soil. However, you should harvest carrots before the soil freezes to prevent dealing with soft and mushy roots. As long as you remove the tops and store the roots somewhere cool, they will remain fresh for at least a month.

Rutabaga

Sometimes described as a sweeter version of a turnip, the rutabaga really shines after a frost. Pull the chunky roots from the ground, cut them into bite-sized pieces, and then roast them for a melt-in-your-mouth treat.

Rutabagas take around 100 days to mature, so plant the seeds in late summer so they size up before short days arrive. Since they’re brassicas, the leaves are susceptible to damage from pests like flea beetles and harlequin bugs. Keeping these pests off tender seedlings will give the plants a greater chance of growing into healthy plants.

Hard frosts often damage rutabaga greens, but the roots can survive these periods. As long as the ground isn’t frozen solid, leaving rutabagas in the garden is safe.

Parsnips

Parsnips deserve the title of the king of fall vegetables. They’re impossible to grow during other times of the year and thrive when cooler temperatures arrive. And while customers frequently request them, they’re often hard to find since they take over 100 days to mature. But the roots’ sweet, nutty flavor makes their long growth time worth it.

Plant parsnip seeds directly in your garden in early to mid-summer if you want to end up with fat fall roots. The greens grow slowly, so keeping the small seedlings well-weeded is important. With the proper care, you’ll end up with large pale roots and vibrant greens in autumn. Parsnips can survive temperatures well below freezing, so don’t worry about leaving them in the ground during the fall and winter.

When it comes time to harvest parsnips, be aware that the leaves can cause a contact rash in some people. The rash is a type of phytophotodermatitis that becomes activated by exposure to light. Wearing gloves and long sleeves is a smart plan if you’re not sure if you’re sensitive to parsnip greens.

Spinach

If there’s one green that everyone should have in a fall garden, it’s spinach. This popular green can survive temperatures into the 20s and becomes supremely sweet during this cooler weather.

Spinach is relatively quick to mature and typically grows from seed to baby leaves in about a month. But remember that day length has a big impact on plant growth! A good rule of thumb is to make sure your plants mature by the time you reach the ‘Persephone Period’ or when the day length drops below 10 hours. Planting spinach seeds at least seven weeks before this period arrives ensures you’ll have big, healthy leaves to harvest throughout the winter.

While spinach can survive hard frost, avoid harvesting frozen leaves. I’ve learned the hard way that frozen leaves will just thaw and turn into an undesirable mush. Wait until the leaves thaw if you want to end up with crisp leaves perfect for salads.

Kale

Kale sometimes gets a bad wrap for being a bitter health food, but anyone who has tasted frost-sweetened kale will tell you this green doesn’t have to be bitter. When kale matures during cool temperatures, it concentrates its sugars and becomes noticeably sweeter. That means planting kale in late summer and early fall will allow you to enjoy salad-worthy greens.

If you’re hoping to harvest mature leaves after a frost, plan to start your seeds three months before the day length drops to 10 hours. If you’ve missed this window, don’t worry! You can direct seed kale all the way up to six weeks before this crucial period arrives.

Although all kale is frost-tolerant, some kale varieties can tolerate cold more than others. ‘Red Russian’ dies back when temperatures drop below 15°F, but ‘Dwarf Blue’ will survive. No matter what variety of kale you’re growing, you can always cover the plants with floating row covers to help them survive well into the winter.

Arugula

Arugula is a peppery salad green that serves as an excellent salad base and pizza topping. Although you can grow it throughout the year, it’s happiest during the cooler months. And since fall frosts help tame the spicy flavor, many people find fall arugula more palatable.

Many people enjoy eating arugula when it’s a tender baby green. This baby green matures within a month, so planting seeds in October will allow you to enjoy salads throughout the winter. Although you can harvest arugula as a cut-and-come-again green, I like to make multiple succession plantings in the fall for a continuous supply of fresh greens.

If you’re growing arugula under row cover, remove the cover during sunny days to increase airflow. Uncovering will help prevent fungal diseases that often cause arugula’s demise. It will also allow you to examine your plants for sap-sucking pests like aphids and thrips.

Bok Choy

Whether you want warming ramen soup or spicy stir fry, bok choy is a must-have in winter gardens. Its mild flavor and flexible nature make it easy to use in the kitchen, and its cold hardiness means it’s easy to grow.

You can eat bok choy at any size, but most varieties take 40–60 days to reach maturity. Planting it in early fall allows it to mature before the first frost occurs. After the plants receive a light frost, you’ll notice their flavor is sweeter and milder.

Although I prefer to grow bok choy from transplants, you can also directly seed it. No matter what growing method you choose, space or thin plants so they are 6–8 inches apart. This will give the plants enough room to expand and allow beneficial airflow.

Cabbage

Boy oh boy, do I love winter cabbage. Maybe it’s my Polish roots, but finding a more comforting meal than a bowl full of sauteed cabbage and mashed potatoes is hard. Fortunately, this hardy vegetable grows well during cool weather and sweetens as temperatures drop.

With that said, some cabbages tolerate cold better than others. Varieties like ‘Copenhagen Market Cabbage’ and ‘Deadon’ can withstand frost, snow, and below-freezing temperatures without missing a beat. Snow can help insulate the plants and help them survive temperatures as low as 0°F.

If you notice that the exterior leaves of your cabbage heads are slimy or discolored, don’t fret. Peeling off these layers often allows you to reveal an otherwise beautiful cabbage. You can use this practice with cabbages you’ve kept growing in the field and those you’ve harvested and kept in cold storage.

Although cabbage can survive cold temperatures, it won’t grow much when shorter fall days arrive. Planting it in your garden in late summer or early fall will help it size up by winter. And, as a bonus, fewer of the most common cabbage pests are active at this time of year!

Tatsoi

If you like bok choy, you’ll probably like tatsoi. This tender Asian green has long, thin stems and small, rounded leaves. Tatsoi is even more cold-hardy than bok choy—the plants can easily survive frosts and temperatures down to 15°F.

You can enjoy tatsoi as a mature plant or a baby green. If you’d like to enjoy larger plants in stir fry and kimchi, get your seeds in during the end of summer. However, you can direct seed tatsoi for baby greens into the middle of the fall.

If you want to treat tatsoi like a cut-and-come-again crop, harvest the largest outer leaves from each plant. Like with other frost-tolerant greens, make sure you let frozen leaves thaw before harvesting.

Radicchio

Many people seem to stray away from radicchio due to its reputation for unpalatable bitterness. And while some types of radicchio are definitely bitter, I’ve found that cold temperatures and frost lead to sweet and flavorful greens with just a touch of bitterness.

There are plenty of radicchio varieties, and some are more cold-hardy than others. These varieties vary in days to maturity, so pay attention to this number to determine when to set transplants out in your garden. I find that planting radicchio seedlings in July and August will lead to full heads when frost arrives.

While you can harvest loose radicchio leaves, these crops will produce tight heads if they’re given enough time to grow before day length fades. Hard frosts may cause the outer leaves to turn brown and mushy, but don’t let this seemingly ugly appearance deceive you! Simply cut the radicchio at the base and clean off the messy outer leaves to reveal a tender and beautiful interior.

Many people are familiar with deep maroon radicchio varieties, but you can also find bright pink options like ‘Rosalba’ and speckled green plants like ‘Lucrezia.’

Radishes

While all types of radishes are milder in cooler temperatures, some larger radishes will only grow in autumn. If you try to grow them in the spring, you’ll find that long, warm days will cause these longer-day varieties to bolt.

I love planting the seeds of radishes like ‘Green Luobo’ and ‘Miyashige White Daikon’ in late summer. As the plants grow, they develop large roots that mellow in flavor when colder temperatures and frost arrives. The crunchy roots lack the sharp taste of warm-weather radishes, so you can enjoy them raw or cooked.

Frost may damage radish leaves, but the roots typically remain unharmed. However, extended periods of below-freezing temperatures can damage the roots. Therefore, harvesting your radishes before true cold weather arrives is best.

Brussels Sprouts

Brussels sprouts have soared in culinary popularity recently, with buffalo fried Brussels popping up on restaurant menus and honey-glazed sprouts shining on cooking shows. But, this crop’s long time to maturity makes growing it challenging. Once you plant your seedlings, they take 80-120 days to produce fat sprouts.

That means you’ll want to get the plants in the ground by late summer to give them enough daylight to mature. However, you don’t have to worry about frost or cold killing the plants—they’re hardy down to 10°F.

Not only can these plants survive frost, but it makes them sweeter! So, letting your Brussels sprouts experience a frost or two before harvest is not only okay but also recommended. You cut down the whole stalk or pick off single sprouts to enjoy.

Turnips

I grow tender ‘Hakurei’ salad turnips in the spring and fall, but fall plantings always reign supreme. That’s because the cool temperatures keep away many common pests and sweeten the plants’ roots and greens.

Along with tender salad turnips, fall is great for cooking turnips like ‘Purple Top White Globe.’ Planting seeds directly in the garden in late summer or early fall will give the roots plenty of time to size up before short days and frost arrive.

Even if the roots are ready to harvest by mid-fall, try to leave the plants in the ground until the first frost strikes. Their increased sweetness will make your patience worth it. I recommend covering the plants with row cover if you expect to dip below 25°F.

Collard Greens

Collard greens are a staple in many fall gardens due to the prolific growth they put on as hot summer days fade to cool autumn mornings. With the right water and nutrients, fall collards can easily reach the size of small umbrellas.

Most uncovered collards can survive temperatures down to 15°F. However, depending on the variety, there’s some wiggle room in their exact temperature tolerance. Regardless, all collard varieties are healthy and sweeter after they experience a frost.

Picking the larger exterior leaves first will allow the inner leaves to mature. While these leaves will grow slower during shorter days, you can continue harvesting collard greens well into winter. Just cover them with floating row cover if the temperature is predicted to dip below 20°F.

Beets

Beets have a bit of a reputation for being earthy and sometimes tasting like dirt, but people who have tasted frost-sweetened beets know just how sweet they can be. Whether you’re growing red beets like ‘Early Wonder’ or golden ones like ‘Touchstone Gold’, allowing your plants to experience cold temperatures causes sugars to concentrate in the roots.

Most beets can survive temperatures down to 20°F, and the roots will be sweeter after they experience cold temperatures. Some leaves may die after a frost, but unscathed greens will continue to grow. Cover your beets with row cover if you’d like to protect the beet greens from cold temperatures while capitalizing on the increased sweetness cold causes.

Beets will slow their growth during fall, so planting the seeds directly in the ground in late summer will allow the roots to size up in time. And don’t forget to thin seedlings so the roots have space to grow.