As a year-round gardener, I grow many vegetable crops in the garden to feed us in fall and winter. These crops need to be able to handle frost and lower temperatures. When I talk about crops that can handle the cold, they are usually grouped together and labeled Cold-Hardy or Cold-Tolerant vegetables.
Cold Hardy vegetables can be killed anywhere from 30ºF all the way down to -5ºF and possibly lower. It covers such a wide range of temperature that they are usually put into two different groups, semi cold hardy which can take light frosts and cold hardy which can survive to 20ºF and below.
First let's talk about the crops that can take several light frosts. Light frosts would be in the 28-32ºF range. Crops that can handle light frosts include lettuce, swiss chard, arugula, radishes, beets, chinese cabbage, collards, cauliflower, celery, turnips, and green onions.
Next is very cold and winter hardy crops. These would be crops that can several frosts and survive down to 20º and below. Crops that can take hard frosts include kale, cabbage, brussel sprouts, spinach, parsnips, carrots, mache, and claytonia.
These are general numbers and individual crop temperature kills can vary based on location.
There is one really cool and really important thing to note here. There is a loophole of sorts that will allow you to have certain varieties that should really be dead after reaching a certain temperature to continue on living. No, it's not a greenhouse, or a low tunnel, though those definitely extend the season.
The loophole that I’m referring to is specific varieties within crop families that are bred to be cold tolerant.
My first experience with the marvel of specific crops bred for cold tolerance was winter density lettuce. Winter density lettuce thrived when all my other lettuce turned into yellow mush at 26 degrees. I was in awe.
Ever since, I’ve been on the hunt for varieties that do better than their counterparts in the cold. Below is a list of some favorites of mine, as well as some I’ve haven’t tried but are raved about to be better in the cold. If you have some favorites you’ve tried that aren’t on my list, leave a comment, I’d love to hear about it.
This list is in no particular order.
*Star is for varieties I’ve grown in my own garden before and love.
*Winter density lettuce-As mentioned above this is a personal favorite of mine. I’ve have it last down to 15 degrees before showing any signs of giving up to frost.
Rouge D’Hiver- This is a red romaine that is as cold tolerant as Winter Density Lettuce. It has beautiful red color that gets more intense with cold.
North Pole- This lettuce variety is said to survive down to 5ºF. Wow. Just don’t try to grow it as a warm season crop since it bolts very quickly.
*Brunswick cabbage- I’ve had this cabbage it last till mid January in our 6b zone with very little damage. Remember to start this one early enough that it forms a head before the daylight hours get too short. 90 days to maturity and stores very well.
January King-This touted to be the most cold tolerant cabbage in existence. Developed in Northern Europe. It has red tinged outer leaves that make this both ornamental and edible.
Cylindra- This one is said to last to 12ºF. A smooth and tender variety that doesn’t get grainy or woody.
*Bloomsdale Longstanding- Even though this isn’t bred for cold tolerance this spinach almost always overwinters (even without a low tunnel) in my zone (US 6b). For colder zones, try some of the other options below.
Winter Bloomsdale- A more cold tolerant version of the original bloomsdale longstanding spinach.
Giant Winter-Heavily Savoyed making it a perfect very cold tolerant crop lasting to 5ºF
*Lacinato Kale- Another crop that will overwinter in my garden. Keep in mind that the closer the plant is to maturity the more frost tolerant they will become.
*Blue Curled Scotch Kale- This kale also overwinters for me. I do keep it under a low tunnel but it lasts all winter!
Vates Kale- Resistant to yellowing in the cold and great for overwintering.
*Hollow crown parsnips- Hollow crown parsnips overwinter in my zone. After frost they get sweeter and even when I picked my parsnips in March they were delicious. In colder areas, cover the ground with mulch to insulate. These will last through the winter!
*Vit Mache is also known as corn salad, is a great little winter green that are incredibly cold tolerant. They even at maturity they are very small so if you want a substantial amount, plant generously.
*Purple Top Turnips can’t handle too much frost even with plenty of mulch (speaking from experience). Where they do shine in the winter garden is when stored at cool temperatures they last for months. Purple Top is a common and dependable variety.
Hakurei This one comes recommended by Niki Jabbour. It’s a hybrid variety that does well in cold and is fast growing (ready in 38 days). They are good raw and cooked, and the greens are delicious too.
Schwarzer Runder Radish Also known as black winter radish. Though this one doesn’t grow past a hard frost, it grows right up to it and stores very well for winter.
*Daikon Radish Daikon is a great winter radish that can survive to 10ºF. Tops will die off but the root will remain intact. It’s a favorite of ours for making kimchi. Delicious!
#12 Asian Greens
Yellow Heart Winter Choy A very cold tolerant chinese edible green. It doubles an ornamental edible that’s beautiful in winter.
Tatsoi Tatsoi is an asian green that can withstand temperatures down to 15ºF. It has a low growing habit and is versatile enough to be used as a spinach substitute.
Claytonia A wild edible in many areas of the US, this plant is incredibly cold hardy. It’s also known as miner’s lettuce because during the days of the Gold Rush miners ate this green to keep scurvy at bay.
#15 Brussel Sprouts
Igor 200 days to harvest. These are frost hardy and sturdy plants.