Produce Spotlight: Microgreens
- Landen Tetil
- Jun 13
- 5 min read
Diving into the food safety considerations of microgreens
Introduction - Microgreens, Not Sprouts!
Micro in size but mighty in flavor, microgreens are a culinary treat and packed with nutrients. It is important to note that, while often used interchangeably, microgreens and sprouts are two distinct crops. Generally, you can tell if a crop is a sprout or a microgreen by looking at the harvested stems:
Microgreens are generally grown in some form of substrate, such as soil or peat, making it necessary to cut the microgreen stems above the substrate level during harvest.
Sprouts, on the other hand, are not grown in any substrate and are not cut during harvest. The sprouts will likely still have their seed pod attached to the stem.
Recalls & Outbreaks
Defining the distinction between microgreens and sprouts is especially important because while both crops are subject to the FSMA Produce Safety Rule (PSR), sprout growers must follow extra preventative food safety measures outlined in Subpart M of the PSR in addition to the general PSR requirements. And rightfully so, considering that sprouts have been the culprit behind “at least 60 foodborne outbreaks since 1988” (Hamilton et al., 2023).
So far, microgreens have never been confirmed as the known cause of an outbreak, though there have been several microgreen recalls over the last decade (Yeargin et. al., 2023). Microgreens have been linked to specific foodborne human pathogen contamination, including Salmonella and Listeria monocytogenes (Yeargin et. al., 2023).
Recalls have included various varieties of microgreens, including broccoli sprouting seeds, broccoli microgreens, alfalfa microgreens, onion microgreens, radish microgreens, baby kale, baby spinach, and baby peas (Hamilton et al., 2023). For example, the 2018 Greenbelt Microgreens Microgreen Mix recall was prompted by a suspected Listeria monocytogenes contamination (U.S. FDA, 2020). In this case, the contamination was discovered on broccoli microgreens through a state sampling program, and the company issued the voluntary recall immediately.
In another case, Wegmans Food Markets, Inc. issued a voluntary recall after supplier testing confirmed Salmonella contamination in the soil substrate used to grow organic microgreens, sweet pea leaves, and cat grass (U.S. FDA, 2023). In both these examples, the microgreen suppliers demonstrated diligence by voluntarily testing their product and initiating prompt recall responses, which has likely contributed to the lack of confirmed outbreaks.
Micro Traits: What makes a risk?
Growing microgreens can seem appealing to a farm for many reasons, including flavor profile, nutrient impact, high marketability, and competitive pricing. However, additional traits should be considered to ensure maximum food safety of these crops. While not all characteristics indicate an immediate food safety risk, all factors should be considered when determining best practices.
Crop & Growing Characteristics
Microgreens are generally more vulnerable to bacterial internalization than mature vegetable plants due to their immature, not fully formed cell structures (Turner et al., 2020).
Surface textures of microgreens support adhesion of pathogens, including noroviruses, which is the leading cause of leafy greens foodborne illness (Riggio et al., 2019).
Microgreens have a short shelf life, which may increase food safety risk. High surface area-to-volume ratio, high respiration and transpiration rates, and delicate leaf structure all factor into microgreens’ rapid deterioration postharvest and make storage challenging (Turner et al., 2020).
Contaminated seeds have been linked to several recalls; it is important to source seeds that have been treated and certified for decontamination (Turner et al., 2020).
Substrate matters! Microgreens grown in soil or other substrates face the risk of cross-contamination from contaminated substrate, as profiled in the Wegmans Food Markets, Inc. recall case (U.S. FDA, 2023).
Microgreens grown hydroponically may be more susceptible to contamination because the warm, humid growing conditions are ideal for bacterial growth (Turner et al., 2020).
Harvesting & Handling Characteristics
Microgreens are usually harvested via cutting by hand, which creates the opportunity for fecal-to-oral contamination from farm workers if poor hygiene practices exist (Riggio et al., 2019).
Harvesting by cutting increases susceptibility to contamination by creating stem scars and tissue damage, making openings on the produce for pathogens to enter (Riggio et al., 2019).
Initial bacterial load can be reduced by washing greens, but excess water can lead to accelerated microbial growth during storage. Washed microgreens should always be dried to reduce bacterial growth (Riggio et al., 2019).
Inadequate cleaning and sanitizing of food-contact surfaces increases the chances for cross-contamination. A dirty harvest knife can readily spread bacteria to all the greens it touches (Riggio et al., 2019).
Recommendations
First, always remember that food safety risks and hazards are inherent in growing crops of any kind - management is the key to good food safety! Even small actions can add up to big food safety benefits. Here are a few practices microgreens growers can implement that will help protect the microbial food safety of their product.
Training, training, training! Workers who know and understand the basic principles of food safety will make better food safety choices.
Humidity control! High humidity is good for the crop, but also good for growing bacteria. Try to balance humidity levels to reduce bacterial growth without sacrificing crop quality.
Rinse, Wash, Rinse, Sanitize! Every food contact surface should be maintained by this four-step cleaning and sanitizing sequence. Remember that hands are a food contact surface, too!
Buy from trusted sources! Purchase seeds and substrate from suppliers that test, treat, and certify their products to be free from contamination.
Make the most of your shelf life! Washing microgreens is not required under the PSR, but if you do wash, be sure to spin dry to remove excess moisture and store under refrigeration temperatures.
Want to learn more?
Michigan Produce Safety Technicians are ready to help you meet your on-farm produce safety goals. We will work with you to identify, manage, and minimize risks to food safety on your farm, and help you create a comprehensive food safety plan to prepare you for an MI Produce Safety Risk Assessment Certificate. Working with produce safety technicians is always free and confidential, and there is no cost to applying for the certificate. Click here to get started.
Sources
Hamilton, A. N., Fraser, A. M., & Gibson, K. E. (2023). Barriers to implementing risk management practices in microgreens growing operations in the United States: Thematic analysis of interviews and survey data. Food Control, 152(109836). https://doi.org/10.1016/j.foodcont.2023.109836
Riggio, G. M., Wang, Q., Kniel, K. E., & Gibson, K. E. (2019). Microgreens—A review of food safety considerations along the farm to fork continuum. International Journal of Food Microbiology, 290, 76-85. https://doi.org/10.1016/j.ijfoodmicro.2018.09.027
Turner, E. R., Luo, Y., & Buchanan, R. L. (2020). Microgreen nutrition, food safety, and shelf life: A review. Journal of Food Science, 290(4), 870-882. https://doi.org/10.1111/1750-3841.15049
U.S. Food and Drug Administration (2020, April 6). Greenbelt Greenhouse Ltd Recalls Greenbelt Microgreens Brand Microgreens Because of Possible Health Risk. Recalls, Market Withdrawals, & Safety Alerts. Retrieved April 24, 2025, from https://www.fda.gov/safety/recalls-market-withdrawals-safety-alerts/greenbelt-greenhouse-ltd-recalls-greenbelt-microgreens-brand-microgreens-because-possible-health#:~:text=Possible%20Health%20Risk-,Greenbelt%20Greenhouse%20Ltd%20Recalls%20Greenbelt%20Microgreens%20Brand%20Microgreens%20Because%20of,the%20product%20or%20the%20company.
U.S. Food and Drug Administration (2022, December 23). Wegmans Food Markets, Inc. Announces Voluntary Recall of Products Containing Micro Greens, Sweet Pea Leaves, and Cat Grass Because of Possible Health Risk. Recalls, Market Withdrawals, & Safety Alerts. Retrieved April 24, 2025, from https://www.fda.gov/safety/recalls-market-withdrawals-safety-alerts/wegmans-food-markets-inc-announces-voluntary-recall-products-containing-micro-greens-sweet-pea
Yeargin, T. A., Lin, Z., Do Prado, I., Sirsat, S. A., & Gibson, K. E. (2023). Consumer practices and perceptions regarding the purchasing and handling of microgreens in the United States. Food Control, 145(109470). https://doi.org/10.1016/j.foodcont.2022.109470
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Article by Landen Tetil, Produce Safety Technician
