Imagine you have three plates of leafy greens in front of you. One each of microgreens, baby greens, and full-size (mature) leaves. Do you know which offers the most nutrition? Which requires cooking? Which is the least or most expensive?
Let’s dig in . . . and define these three categories of greens. The differences are based, simply, on their stage of growth. Depending on the specific variety, microgreens are harvested 10 to 25 days after seeding; baby greens from 18 to 35 days; and mature greens require as long as 40 to 70 days.
If you’re not familiar with microgreens, the tiny, immature plants are produced from the seeds of vegetables and herbs. They’re harvested above the soil, although they can also be grown hydroponically, when 1 to 3 inches tall and their cotyledons (tiny seed leaves) have formed. (Sprouts are technically the first growth, appearing in a few days, but they’re not grown in soil. You eat the root, seed, and stem; with microgreens you eat the stem and leaves.) The itty-bitty plants, eaten raw, can pack a powerful flavor punch as some varieties, such as arugula, cress, mustard, and radish, are quite peppery or sharp. Others, like broccoli, cabbage, tatsoi, and sunflower and pea shoots, are mild tasting. Chefs have enjoyed using microgreens as garnishes for their flavors and their striking shades of green, purple, and red.
After the cotyledons fall off and new, true leaves form, this is the baby green stage. The tender 3- to 5-inch leaves take about twice as long to grow as microgreens and require a more nutrient-rich soil. Baby leaves — think kale, spinach, arugula, mustard greens, and mizuna — can either carry a sharp bite or run milder than their full-grown counterparts. They’re usually eaten raw in salads, but can also be quickly wilted in a skillet.
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Mature greens are full-size leaves that generally require cooking to become tender. With kale and collards, the thick fibrous stems are removed, as are thicker spinach stems. Chard stems can be chopped and cooked along with the leaves.
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At We Grow Microgreens in Hyde Park, co-owners Lisa Evans and Tim Smith grow the tiny edible plants in soil in 10-by-20-inch flats in their greenhouse. The couple spreads what might be a thousand seeds per flat in moistened potting soil; in a few days’ time the seeds germinate and are then exposed to light. Because they’re so delicate, great care is required. “Microgreens are very fragile, and you can’t have huge fluctuations in temperatures,” says Evans.
Nutritionally, microgreens are powerhouses for their minuscule size. In a 2012 study, USDA researchers found that in a sample of 25 commercially available microgreen varieties, the tiny plants had higher concentrations of vitamins and carotenoids (A, C, E, K, and some B vitamins) than their mature plant counterparts. There were wide variations among the varieties, but overall, compared to mature leaves, microgreen cotyledon leaves had higher nutritional densities.
Gene Lester, Ph.D, one of the authors of the 2012 research published in the Journal of Agricultural and Food Chemistry, explains that microgreens’ seed leaves act as a “storehouse of nutrients,” needed to grow root systems and the plant’s true leaves. Lester, who is national research director for the USDA’s Agricultural Research Service, said nutrients in microgreens are more concentrated than those in mature leaves because of a “dilution effect.” “The smallest leaves have the same number of cells as larger, adult form leaves. As the leaf grows and the cells get bigger, they fill with water.” He likens it to how you need about a third as much dried herbs as fresh herbs for seasoning food because fresh herbs contain more water. It isn’t the vegetable’s aging process that diminishes nutrition content in mature leaves, he says. It’s simply the amount of water stored in the plant’s cells that dilutes nutrient density.
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Other studies have shown similar high-nutrient concentrations for baby greens. “Nutrition is more condensed in younger versions of vegetables,” says Lester.
At this point you may be wondering whether it’s worth eating mature greens at all. Yes, it is, because all leafy greens are great sources of vitamins and minerals, important for good health. “There’s a tremendous amount of nutrition in mature greens,” says Lester. Also, the fiber and water content in large leaves will provide greater satiety. And the larger leaves are generally less costly.
“Microgreens are expensive to grow because they’re so labor intensive,” says Smith of We Grow Microgreens. “You’re always having to seed, water, and harvest before you lose the plant.” A slight delay in harvesting can mean yellow leaves and stretchy stems.
At Seeds of Solidarity in Orange, co-owners Ricky Baruc and wife Deb Habib grow and sell various combinations of greens. Their popular salad mix has baby mustard, mizuna, tatsoi, arugula, spinach, and lettuce. Larger leaves are combined for stir-fry and braising mixes. Full-size bunch greens, such as chard, bok choy, collards, and kale, “hold up better when you cook them,” says Baruc. He adds that people like to use mature leaves for juicing.
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In other parts of the vast vegetable world, true baby vegetables are harvested younger and smaller than their full-grown counterparts, while some so-called “babies” are another species. Little onions are planted close together so they won’t grow large and are picked early. Baby squashes, including zucchini and yellow summer squash, are harvested young, as are true “new” potatoes. Baby corn are the initial tiny ears on the stalk. Baby bok choy can be either a dwarf variety or a small, immature plant. Broccolini isn’t a baby, but a hybrid, a cross of broccoli and Chinese broccoli. And then there are those thumb-size “baby carrots” that aren’t babies at all, but machine-cut pieces of regular (and often older) carrots. True baby carrots are smaller and slimmer than adult-size, sold in bunches with their top greens intact.
Incorporating leafy greens into your meals is easy. Toss baby greens and microgreens in salads to vary flavors, textures, and colors. If you’re going to cook baby greens, do it quickly to just wilt the leaves. Microgreens can be sprinkled on cooked fish, poultry, vegetable dishes, and grain bowls. When cooking large leaf greens, it’s better to steam than boil them so more nutrients are preserved. Toss cooked greens with a little olive oil, garlic, and herbs, if you like. Add greens to soups and omelets, toss them into stir-fries and casseroles, and make a “green” pizza. No matter how large or tiny they are, make sure to gobble up those good-for-you greens.
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Lisa Zwirn can be reached at lisa@lisazwirn.com.
Lisa Zwirn can be reached at lzwirn9093@gmail.com.