Winter 2025
Growing Microgreens
by David George
Garnish Canapes with microgreens. Photo courtesy of Shutterstock.
As winter settles in, many UC Contra Costa County Master Gardener volunteers tend to their INDOOR veggies and one of the hottest trends in indoor food production right now is growing “Microgreens”. These plants only require water, indirect sun, a flat container, and 2-4 weeks of growing time before harvest. Best of all, they are inexpensive to cultivate and packed with flavor.
What are Microgreens?
Microgreen growing is easy. Photo courtesy of Kathy Craig.
They are young edible vegetable or herb seedlings, harvested when their stems are 2-4 inches tall and their starter leaves, called cotyledons, have fully formed. These seedlings are sown densely in flat trays or hydroponic containers. They are in their first several weeks of life when you harvest them and, at this stage, they only require water and indirect sun. Microgreens are a fun and flavorful addition to any meal.
Getting Started
Seed packets can be purchased in garden centers or online. A word of advice: buy organic (untreated) seeds and check packet expiration dates. You will need one or more shallow 1-2” growing trays with bottom holes for water drainage and absorption. Or you can use sealed hydroponic trays with a fine mesh separating seeds on top from a water basin. You will also need a spray bottle for tap water spritzes, sterilized scissors for harvest, a location with 6+ hours per day of indirect light (or a grow lamp), and a tray cover for the first week or so. Aluminum foil works well for this.
Hydroponic Tray. Photo courtesy of Andrea Salzman.
For shallow open trays, purchase a sterile growing medium such as coconut coir, recycled cardboard, or jute to maintain consistent seed moisture. For sealed hydroponic trays, you’ll need a growing pad cut to size, a hydroponic base of fine mesh screen, and a sterilized container.
Growing Technique
Microgreens can be grown in recycled berry containers. Photo courtesy of Pixabay.
Soak larger seeds like peas and nasturtium, overnight. When you are ready to start seeding the microgreens; first, mist the tray base with water. Add your sterile growing medium. (Don’t use potting soil or other fertilizer mixes, as seedlings do not need nutrients and it’ll produce an unpleasant off-taste in sprouts.) Evenly scatter about 1 tablespoon of seeds per tray on the growing medium. Spritz the seeds and growing medium with tap water from the spray bottle to the wetness of a “wrung-out sponge”. Cover the container and check each day until nearly all seeds have germinated. Then remove the cover and place them in bright, indirect sun. Maintain consistent moisture by placing the tray in a larger watertight container that holds enough standing water for the growing tray to absorb it into its growing medium.
Hydroponic Growing. Courtesy of Andrea Salzman.
Harvest time varies by plant type but generally is about 2 weeks after germination when seedlings are 2-4” tall, and starter leaves are fully formed and green. Use scissors to clip seedlings just above soil level and wrap them in paper towels (without washing them) and they’re ready to eat, but they can be refrigerated for up to a week. Compost the remaining plant material and throw out the old growing medium. Sanitize reusable trays in a dishwasher or hot soapy water.
Good Choices to Get Started
Radish makes a tasty microgreen in salads. Photo courtesy of University of Florida Food & Agriculture.
Slow-growing (18-26 days) microgreen varieties include radishes, beets, arugula, cabbage, peas, spinach, parsley, or herbs. Fast-growing (10-15 days) types include arugula, broccoli, cabbage, kale, kohlrabi, mustard, amaranth, and spinach.
Microgreens can spice up morning eggs, salads, pasta, taco salads, spring rolls, or other entrees. They add freshness, taste, color, variety, and interest to any meal.
Link to webinar: Growing Microgreens, by Andrea Salzman
https://www.youtube.com/watch?v=QHq968jFyA0
Short video demonstration of Growing Microgreens, by Andrea Salzman (3:32 mins.)
