Jack Frost nipping at your nose might not be the sweetest sensation. But, Jack Frost icing the leaves on winter greens is indeed a sweet reward. Cool-season crops in the Brassica family, such as kale, collards, Brussels sprouts, cabbage, mustard, broccoli, and kohlrabi, benefit from a few frosts. Those nights that dip into mid-20 degree temperatures seem anything but beneficial for leafy greens, but the plant defends against freezing weather by turning starch to sugars. Simply put, plants make their own anti-freeze. And that anti-freeze is TASTY.
Sound doubtful? My husband and I succumbed to the kale craze several years ago, growing as many varieties as we could fit in our kitchen garden. Lacinato, or Tuscan kale, quickly became my favorite because of its flatter (vs. frilly) leaves. We used it in soups and stews, roasted kale chips, and chopped it raw for fresh salads (like this Lemony Kale Salad). Then one December, shivering in sweaters and defrosting in front of a toasty fireplace in our kitchen, we noshed on the fresh salad. At first bite, we both stopped mid-chew and looked at each other wide-eyed. The same kale recipe we’d made over and over again was altogether new. Eureka! We licked the bowls and made it daily until the plants were stripped naked, looking like mini Dr. Seuss trees next to the fat cabbages.
The same held true for the collard greens we cooked for a lucky New Years Day. Recipes will often suggest a touch of sugar or honey to sweeten the pot, but you may not need it if you’re lucky enough to harvest after a few nights of freezing weather. The same also holds true for root crops in your winter garden, as parsnips, carrots, rutabagas and turnips are better left in-ground for sugar to convert from starch. Of course, there’s no calendar date that applies across the country: know your regional window of hard frosts (temperatures in mid-20 degrees) before the garden is buried under snow. You can also extend the harvest with a simple row-cover protection when temps dip further.