What do these 15 vegetables and herbs all have in common?
- Watercress
- Chinese cabbage
- Chard
- Beet greens
- Spinach
- Chicory
- Leaf lettuce
- Parsley
- Romaine lettuce
- Collard greens
- Turnip greens
- Mustard greens
- Endive
- Chives
- Kale
They’re the 15 highest-ranking plants on a list of 41 powerhouse fruits and vegetables (also known as PFVs), based on a study by the Centers for Disease Control and Prevention.
While the word “powerhouse” might make you think it’s nothing more than just another trendy health term (kind of like “superfood”), it actually does have scientific merit. Powerhouse foods are a legitimate classification for the super nutrient-dense fruits and vegetables that greatly reduce the risk of chronic diseases (such as cancer, diabetes, and heart disease). The PFVs that made this list have a high level of essential nutrients relative to the amount of calories they provide.
But there’s another common thread that gardeners, in particular, will find interesting… The top 15 on that list are all cold-tolerant vegetables. You might even be growing some of them right now, and in most hardiness zones, you can continue to grow them through the depth of winter without a greenhouse.
I’ve noticed that in my winter garden, these vegetables absolutely thrive compared to when I try to grow them in the heat of summer, which they often rebel against (think: early bolting or tough and bitter leaves). And as we can see in the CDC study, the top half of the list (with the most nutrient-dense vegetables) is dominated by cold weather-loving cruciferous crops (watercress, Chinese cabbage, collards) and leafy greens (chard, beet greens, spinach).
What about the vegetables on that list that can only be grown in summer? Surprisingly, none of them had a nutrient density score above 42! Hmm… We may extoll the health benefits of our antioxidant-rich tomatoes, but apparently they can’t hold a candle to the nutrients in beet greens and leaf lettuce.
And that’s got me thinking… These cold-tolerant plants are able to survive winter by expressing special cold-tolerance proteins, accumulating sugars in their cells, and modifying their cell membranes to withstand freeze stress. Maybe—just maybe—some of these chemical adaptations also contribute to the benefits these plants have on human health? What if we learned that winter gardening is not only possible for most people, but healthier for us too?
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Growing powerhouse vegetables
The top 15 plants on the PFV list are extremely cold-hardy, and you can push their limits in winter (in USDA hardiness zones 5 and above) by growing them under a simple low tunnel covered with midweight frost cloth.
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Gardeners in colder zones can grow them in spring or fall (for better flavor and production). Most of these vegetables also grow well indoors in front of a sunny window.
Watercress, which tops the list with a nutrient density score of 100, is actually a perennial in zones 6 and above (possibly zone 5 with winter protection). It makes an excellent addition to your perennial vegetable garden (and no, watercress does not need to be grown in or near water—it just needs consistently moist soil).
Nutrient-dense chives, which also made the list, are a must in every perennial herb garden. They’re so prolific that the original six bunches I planted years ago have multiplied into dozens of bunches that I’ve transplanted around the garden and given away to friends. And because I love a multipurpose plant, chives are one of the best pollinator-friendly flowers.
If you want to try something different, you can also amp up the nutrient density of powerhouse vegetables by growing them indoors as microgreens, which—ounce for ounce—have more nutrients than mature plants. (Mustard and turnip microgreens are among my favorites for salads; I get my sprouting seeds here.)
