Planting cool season vegetables can allow you to harvest fresh produce into the winter in milder climates. Give these cool weather crops a try.
We may not get the milder summers and fall beauty that northern climates have, but here in zone 8, we do get to grow some vegetables right on into winter. There are some greens and root crops that do well – even tasting better- after our lighter freezes (28-32 degrees F).
But then there are some that really just turn to mush and are inedible. Most vegetables, even the cold-hardy varieties, would do well to be covered at temperatures below 25 degrees.
So what is it that makes one vegetable withstand a freeze and another not so much? And which vegetables can tolerate the mild frosts and freezes?
Cool weather crops
To answer the first question, it really comes down to the sugar content of a vegetable. As the temperatures drop, the water in the cells expands as it begins to turn to ice. Eventually, when the freezing point hits, the cell walls burst and frost or freeze damage is incurred.
Cold-hardy vegetables and vegetable varieties are often higher in sugars than their counterparts. Sugar water freezes at a lower temperature than regular water, allowing the cell walls of the higher-sugar vegetables to stay intact. You may notice, too, that during a slow cool down of fall and into winter, vegetables get sweeter over time, thereby giving them a high cold-tolerance as winter sets in.
Planning ahead with cool season crops
Planting these cool season vegetables long before the onslaught of light freezes really helps. Mature plants seem to tolerate the cold better than immature plants. And, because moisture holds heat, nights of high-humidity or precipitation tend to be safer for plants than the cold, dry, windy nights.
Cool season vegetables to consider
First of all, when looking for seed, seek out the most cold-hardy varieties of any of these vegetables. Secondly, stick with the greens and roots. Fruiting plants like tomatoes, squash, pumpkins, and peppers will keel over as soon as a frost hits.
- Brussels Sprouts
- Tatsoi – This mustard variety can be found hardy down to 15 F!
- Cabbage – Chinese cabbage is often more cold-hardy than green and red cabbages.
All of the above cool weather crops often survive right through to spring in a milder climate such as ours. However, when night-time temperatures are set to drop below freezing, we often cover the more vulnerable lettuce, cauliflower, beets etc. with blankets or row covers.
One more option for growing food into winter is the over-wintering crops. These are things that withstand the cold and might give you small harvests during the cold winter but will surely come to life in spring and deliver. The most common of these are garlic and onions but we have also done fava beans and greens with great results.