Cold Tolerant Plants (& why it matters during climate change)

Have you ever wondered why kale survives through winters, but winter squash leaves wilt at the slightest frost? Here's how cold-tolerant plants survive freezing temperatures.

Cold Tolerance in Plants Comes Down to These Factors:

• Thick Leaves Save Plant Lives:
  Plants like brassicas have thick waxy leaves, so they can maintain their structure in cold weather.
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• Protective chemicals:
  Cold hardy plants might trigger the production of certain chemicals, which help the plant to withstand the stress of freezing temperatures.^{1
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• Maturity Time:
  Flowers are often the most tender part of a plant. If flowers set either before the first frost or after the last frost, then the plant will likely produce a crop. ^{2
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• Gradual Exposure:
  Hardening plants off, or the gradual exposure of colder temperatures, can help plants to produce beneficial chemicals in their leaves and even change on a cellular level so that they become more frost tolerant. ^{3
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• Starches turn into Sugars:
  Some plants are able to transform their starches into sugars, which protect their cells from freezing. Carrots, beets, and turnips are examples of crops that do this - and taste excellent after a few cold spells.^{4
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• Purple Color:
  When compared to plants with green leaves, purple plants actually have a lower freezing point due to their anthocyanin content. Purple Sprouting Broccoli is well-known for this effect. ^{5
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• Blue Color:
  Similarly, plants with a blueish tint to their leaves can also survive in cold temperatures due to anthocyanin. ⁶

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What are the best cold-tolerant vegetables for winter gardening?

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Why This Matters - The Benefits of Planting Cold-Tolerant Species:

Alright, so you might be wondering why I think all of this is good to know as a regenerative gardener. Understanding these plant traits is important for a few reasons:

1. It helps with increasing your self-sufficiency.

If you live in an area with mild winters and/or have access to a greenhouse, you’ll be able to reduce your food bill by growing plants almost year-round.

You’ve probably noticed that food is expensive and prices keep creeping up - especially if it’s organically grown.

When you understand which plants can survive throughout your winter conditions, you’re able to extend your growing season and supplement your meals with home grown produce.

2. It helps with carbon sequestration.

One of the main principles of regenerative gardening is to keep the soil planted for as long as possible.

This is because when crops are growing, photosynthesis is happening.

And if photosynthesis is happening, so is carbon capture. Carbon levels in the soil help to not only sequester this abundant greenhouse gas, but also helps to build soil health.

Even though photosynthesis slows down in the winter, it still supports the soil overall.

Keeping the soil planted also helps to reduce soil erosion.

Even if you’re not interested in growing 100% food crops in your garden over the winter, some cover crops are extra cold hardy and will help to provide organic matter and nutrients for your soil.

Examples of winter growing cover crops include winter rye, hairy vetch, and fava beans.

You can learn more about the benefits of growing cover crops here.

3. Biodiversity is important year-round

Not only does a biodiverse garden capture more carbon in the soil, but it also supports a wider variety of insects, wildlife, and soil microbiota too.

Insects need spots to (literally) chill out over the winter. Some insects lay their eggs in certain plants so that their larvae can have something to eat as soon as they’ve emerged.

Some insects need nectar or other food sources quite early in the season, when things are scarce.

For example, did you know that queen bees emerge in early spring, and spend their first few days looking for food?

Keeping the garden planted will in turn add more organic matter to your soil, which will help increase your soil biome population. Birds will come into the garden in spring, happily eating worms found in healthy soil - and maybe they’ll eat some slugs and cabbage loopers while they’re at it, too.

4. It allows us to be more efficient with resources

In my PNW climate, we are spoiled in terms of rainfall right up until about mid-June, where we have a few months with hardly any rain at all.

That means when it’s primetime in the garden, I need to figure out a source for water in order to keep my plants healthy. We collect rainwater all year to use in the summer, and every drop of it is precious.

However, if I can grow some food in the fall, winter, and spring, I don’t need to manually water those crops at all.

Additionally, some garden pests just aren’t around in the cooler months, so you can avoid them by growing certain crops in the off season.

Action Steps for Regenerative Gardeners:

• Keep the ground planted as much a possible - grow a cover crop during the off season to help build soil health and maximize soil carbon storage.
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• Keep plant roots in the ground when possible - this helps keep carbon in the ground. It also minimizes soil biome disruption. Obviously you can’t do this with root crops like potatoes and such.
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• Experiment - techniques like seed saving, landrace gardening, row covers, and greenhouses can all help your crops to adapt to the cold weather.
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• Water Conservation - Collect rainwater during wet months to use when it’s dry to save this precious resource.

References + Deeper Dives:

1. NIH 1
2. NIH 2
3. Science Direct
4. Giving Ground Seeds
5. Oregon State University
6. Botanical Interests

I have a list of recommended backyard greenhouses here - no Amazon links

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