Microgreens 201

Departments - Hydroponic Production Primer

For growers looking to improve their microgreens program, here are tips to save time and money.

August 16, 2022

Nearly anything can be a microgreen, it just needs to be harvested at the right stage.
Photos courtesy of Christopher J. Currey

“If I could grow only microgreens, I would” is a statement I have heard a number of times from growers. There is a reason why: microgreens are one of the most valuable crops to grow on a profit-per-square-foot-week basis. Unfortunately, microgreens aren’t consumed in volumes that could justify growing only microgreens, but they are a very complementary crop to programs such as leafy greens and herbs. Microgreens 101 (bit.ly/microgreens_101) focused on the fundamentals of microgreens production, from seed to harvest. The goal of this article is to give you a few more ideas to improve microgreen production.

First: always look and listen for new ideas or, for microgreens, new crops. The concept of microgreens is simply referring to the developmental stage of leafy plants. Said more simply, nearly anything can be a microgreen, it just needs to be harvested at the right stage. Many of the microgreens grown are also crops grown for harvesting at a more mature phase. While the Brassica family (Brassicaceae) is a plant family rich in microgreen species, there are more species out there that are suitable for microgreens. Don’t be hesitant to test new species and varieties. When testing new crops, don’t grow them as a mix, grow different species and varieties individually so you can make the most accurate assessment of their suitability.

Speaking of mixes: Remember that mixes can be blended after harvest and don’t have to be grown during production. This allows you to blend flavors that work well together comprised of species that have different schedules or cultural requirements.

The primary direct costs associated with microgreens are seed and substrate. Cutting down on seed costs can be a challenge, since fresh-cut microgreens do not regenerate after being harvested, unlike other young or mature leafy greens that can be harvested more than once. Microgreens are harvested by cutting the entire shoot below the cotyledon, so there is no apical meristem nor adventitious shoots that can produce additional growth to harvest. This makes trimming seed costs impossible.

Consider selling living microgreens for the consumer market and to commercial kitchens and chefs.

However, there is an opportunity to reduce substrate costs for clean and careful growers. The majority of microgreens are grown on some type of stabilized substrate, including rockwool mats or sheets of cellulose or burlap cut from large rolls. Once microgreens are harvested off these substrates, I have seen producers flip the substrate over and seed onto what was previously the bottom of the substrate. This allows for a second crop to be grown on the substrate, essentially cutting substrate costs in half. Using this approach does come with some risk. The substrate is not pasteurized in between crops and there are roots from the first crop that will be dying. However, if careful attention is paid to managing pathogens — both human and plant pathogens — in production systems and nutrient solutions, this strategy can be used successfully.

One way to look at improving the post-harvest life of your microgreens is to consider selling living microgreens as opposed to cut microgreens. Much like living herbs or living lettuce, leaving the roots on microgreens will extend their shelf life compared to when they are cut. This improved postharvest life can be a noticeable benefit for consumers, but the improved shelf life also keeps your products looking better in the marketplace, longer.

But the supermarket and home refrigerators aren’t the only place living microgreens will stay better, longer. It is commercial kitchens and restaurants, too. Living microgreens result in the freshest ingredients for commercial kitchens. The stabilized substrates mentioned above, including rockwool and cellulose substrates, are very well-suited for growing (and transporting) living microgreens. For consumers, packaging needs to be able to hold wet substrate, protect shoots, and allow ample air exchange. For commercial clients, larger-sized sheets or sections of substrate can be used, depending on how they are stored in the kitchen.

Microgreens can be a profitable selection in your product mix. These quick-growing and flavorful crops can be produced in a variety of manners, making them flexible for your operation. When the fundamentals of production are taken together with the tips provided in this article, you have a recipe for success.

Christopher (ccurrey@iastate.edu) is an associate professor of horticulture in the Department of Horticulture at Iowa State University.