Growing Microgreens

by Sonoma County Master Gardener Tweedy Olson

Microgreens are simply greens, lettuces and herbs that are harvested when they are quite young—less than two weeks after seeding when they are an inch or two tall. You may start with a pre-packaged seed mix, select specific microgreens or choose a Mesclun mix to grow as microgreens. Popular crops grown as microgreens include mustard, kale, endive, arugula, beet greens, Tatsoi, radish greens, watercress, Mizuna, peas, cabbage, basil, lettuce (any) and spinach.

These petite greens are delicious and nutritious. They also are expensive—unless you grow them yourself. Microgreens may be used as an accent in salads or sautés or as a garnish. Greens harvested at seedling stage contain four to six times more nutrients as their full-grown counterparts.

Growing microgreens is possible any time of the year, and they add a bit of freshness during the winter when grown on a sunny window sill. One mix of special microgreens seed includes flavorful arugula, ultra-nutritious broccoli and mild red chard. A zesty and spicy blend may contain ‘Bull’s Blood’ beet, herbs such as ‘Pepper Cress,’ ‘Purple Vienna’ kohlrabi, ‘Mizuna’ mustard and ‘China Rose’ radish. Mesclun seed mixes are a good choice for microgreens. Mixes such as Paris Market Mix and Asian Baby Leaf Mix (reneesgarden.com) contain a blend of greens that tend to sprout at the same time.  

In mild climates, microgreens can be grown outdoors year round, except winter in cooler regions. But you also can grow them inside under bright light. They will need at least four hours of sunlight. If grown indoors, place them in a south-facing window, but an eastern- or western-facing window will do as well.

If growing in the ground, till in three to four inches of compost or other mature organic material into the soil. If growing in containers, use a pot at least 10-inches deep filled with potting soil to about an inch below the rim. Sow seeds 1/8-inch deep. You may mix seeds with fine sand to help with even distribution when sowing.

Growing conditions require full sun and moist soil. Fertilizing is not necessary if you have plenty of organic matter in your garden bed. If planting in a container, add a bit of granular organic fertilizer to the soil before you plant. You may fertilize every other week with fish emulsion, or use a granular organic fertilizer according to instructions.  Remember to keep the soil consistently moist (not wet). If planting Brassica seeds in your mix (mustard, kale, etc.) and cabbageworms are a problem, you may cover your microgreens with a floating cover to protect them.

Think about companion plants: plant microgreens alongside kale, chard and lettuce that you are letting grow to maturity. Include some edible flowers like pansies and violas in the cool season or nasturtiums in the warm season.

Microgreens are intentionally harvested when they’re very young, often under two inches tall—ten or less days after seeds are sown! Use scissors to clip clusters just above the soil line right after the first set of true leaves form. True leaves follow the initial, simple-looking seed leaves and resemble the leaves of the mature plant.

Unlike Mesclun or baby greens, you will not have additional harvests from a planting of microgreens. Because the plants don’t have much time to develop and you’re snipping off everything except the very bottom of the stem, the plant cannot generate new growth. You can plant another crop immediately after harvest by scattering fresh seed and covering it with soil. You don’t need to remove the old roots; they are good sources of organic matter.

Microgreens are simple to grow are ready in a flash. They will provide you with a quick harvest for not much work. They definitely deserve a spot in your garden or on your window sill.