This purple broccoli has been amazing to follow through the season. It had a very rough period when flea beetles found it mid-summer, bounced back big time in August but ended up bitter during the peak of late summer heat. Now it has found its "sweet spot".

The other day Ev and I were planting garlic and digging the final harvest of potatoes from the garden when Ev got curious about the florets of purple broccoli still looking amazing in one of the beds. She reached to snap some off for a nibble when I interjected with, "Wait! those have become so bitter!" And indeed, they had been bitter... but as it turns out were now super tasty, complements of the recent frost.

So, why exactly do some edible plants develop their best flavour after cool weather or frost has hit them? The answer has a lot to do with why these same plants also look so undisturbed by frost; cold-tolerant veggies have built-in anti-freeze mechanisms that work by converting starches into sweet-tasting sugars, lowering the temperature at which their cells freeze. Some of these plants, like collard greens, can remain active down to temperatures as low as -15C!

The best veggies to leave out in the cold

The common denominator among many of the cold-tolerant edible options for prairie gardeners is that they are brassicas or cabbage family plants. But there are others! Check out the list below.

1) Beets (so long as these are harvested before the ground freezes)

2) Broccoli (including sprouting broccoli, which requires cool weather to form the small florets which it is famous for)

3) Brussels Sprouts (it often catches gardeners off guard to imagine brussels sprouts surrounded by snow... but this is perfectly fine!)

4) Cabbage (really sweetens up nicely in fall, but is one of the few brassicas that works well in summer as well)

5) Carrots (these have to be harvested before the ground freezes solid... but that is a few weeks away!)

6) Collards (the most cold-tolerant of them all, ironically, as collard greens are very much associated with the south)

7) Kale (imagine: no flea beetles and no cabbage moths to worry about when you enjoy these in the fall garden)

8) Kalettes (famously developed by a Manitoban who now lives in England, these plants produce both kale and brussels sprouts on one plant!)

9) Green Onions (really, keeping a patch of green onions could not be easier and these are fully winter hardy in Manitoba)

10) Mustards (there are many to choose from with a range of flavour profiles, but for sure the bigger, sturdier types do best in cold weather; tat soi is exceptional)

11) Spinach (so much better when grown as a fall crop; sow the last week of August in our region)

12) Turnips (not every kid's first choice for dinner, but maybe a little more so when harvested after a couple of frosts!)

The amazing thing is that repeated exposure to frost actually further develops the sweetness (thus flavour) of cool-season crops, so go ahead and leave these outdoors as long as you can!

Originally posted on October 22, 2021