I’ll admit it. I’m a gambling man. Many gardeners begin cleaning out their garden right after the first frost. While they know that many species in the garden can handle light frosts, many like to go ahead and harvest whatever produce remains, and clean up the garden before a really hard frost kills everything.
But I like to push our garden’s limits, because many of the fall and winter vegetables left growing in the garden get sweeter and sweeter as the days get colder and colder, and shorter and shorter. As long as there isn’t a killing frost, the garden just gets better and better. That which doesn’t kill us makes us sweeter, so to speak. So why does this happen?
Many of the plants from the Brassicaceae family - including brussels sprouts, turnips, broccoli, cabbage, cauliflower and rutabaga – survive the downturn in temperatures by turning some of their stored starches into soluble sugars. This helps prevent the liquid in the leaves from freezing (think of how sugary liquids don’t fully freeze in your freezer). And since the plant sap doesn’t freeze, it doesn’t expand. And since the sap doesn’t expand, it doesn’t rupture cell walls. Which prevents plant stems from turning into limp spaghetti noodles.
So as the plants catch a chill, they fill up with sugar. Which, when it comes to slightly bitter veggies like brocolli, brussels sprouts and collards, is a delightful thing.
But I’ve noticed another quirk that happens to many plants left in the garden through the first several frosts. They turn purple. Which is also a delightful thing when the rest of the landscape looks brown and barren. After a little research, I’ve learned that the change – like most plant changes – can be traced back to photosynthesis. Remembering back to high school, you’ll recall that photosynthesis uses sunlight and carbon dioxide to create glucose (a sugar) that is used to help the plant grow. They do this with the help of chlorophyll. – a chemical that turns the plant green.
But shorter days means less sunlight. Which means less photosynthesis. Which means the plant starts shutting down. Which means the chlorophyll goes away. Which means less green. The same pigment that makes purple cabbages purple is present all season long even in the green-colored Brassicaceae species. But it’s invisible until the green chlorophyll fades.
So. There’s our little cold-weather garden lesson. You don’t really have to understand it in order to enjoy both the taste and the prettiness. But winter’s coming. You may as well settle into reading about gardening rather than doing it.
Click on any of the below pictures to start a slideshow, and share with us the things you find in your late season garden in the comment section.