Microgreens are young vegetable greens harvested just after the cotyledon leaves have fully developed, sometimes with the emergence of the first true leaves. They are prized for their intense flavor and nutrient density. The final harvest weight is highly variable, depending on the specific plant species and the controlled environment in which it is grown. There is no single, fixed answer to how many ounces a tray will yield.
Establishing a Baseline for Microgreen Yields
The expected weight of microgreens harvested from a standard 10×20 inch tray is primarily determined by the species being cultivated. Growers categorize microgreens by their fresh weight yield, which is the most direct measure of a tray’s productivity. Yields range widely across varieties.
Heavy yielders are typically large-seed varieties that produce substantial biomass quickly. Pea shoots and sunflower microgreens are prominent examples, yielding 14 to 27 ounces per 10×20 tray. These species efficiently convert the seed’s stored energy into fresh weight.
Moderate yielders include many of the Brassica family, such as broccoli, kale, and cabbage, along with radish varieties. These greens generally produce between 6 and 12 ounces per tray. Radish microgreens often fall on the higher end of this range, sometimes reaching 11 to 12 ounces.
Lighter yielders are often aromatic herbs and small-seeded varieties like basil and amaranth. These crops focus less on mass and more on flavor and color. Basil often yields around 3.5 to 4 ounces per tray, while amaranth tends to produce about 3 ounces.
Key Variables Determining Final Harvest Weight
The broad ranges in yield for any single species result from several controllable factors that drive plant growth and biomass accumulation. Optimizing these conditions for each variety can significantly shift the final harvest weight toward the upper end of its potential range.
Seed density, or the number of seeds planted per square inch, is a major factor influencing total biomass. Increasing the sowing density generally increases the overall yield per tray because more plants contribute to the total fresh weight. However, overly high densities can lead to overcrowding, encouraging competition for light and nutrients, and potentially resulting in thinner stems or increased disease risk.
The quality and quantity of light supplied are directly correlated with the seedlings’ ability to accumulate mass through photosynthesis. Light intensity, measured in micromoles per square meter per second (\(\mu\text{mol}\cdot\text{m}^{-2}\cdot\text{s}^{-1}\)), significantly impacts fresh biomass; higher intensity leads to greater accumulation. The specific light spectrum, including the ratio of red, blue, and green light, can also be manipulated to influence morphology and biomass.
Harvest timing is a third variable, as the fresh weight of the microgreens increases exponentially during their short growth cycle. Microgreens are typically harvested when they have fully developed cotyledons and before the first true leaves emerge. Delaying the harvest by even a day or two can increase the total mass.
Accurate Measurement and Calculation of Tray Yield
To accurately determine the ounces of microgreens produced, a standardized measurement method is necessary, starting with defining the growing area. The 10×20 tray refers to a standard flat used in commercial and home growing, offering a uniform surface area for comparison. Reporting yield in ounces per 10×20 tray allows for easy benchmarking across different growing operations.
The actual measurement requires the use of a tare weight. Tare weight is the weight of the container, growing medium, or anything else that is not the microgreen product itself. This weight must be subtracted from the total harvest weight. By setting the scale to zero with the empty tray and medium, the grower ensures the final measured weight is the net weight of the microgreens alone.
For operational efficiency, the tray yield can be converted to a metric like grams per square foot (\(\text{g}/\text{ft}^2\)). A standard 10×20 tray covers approximately 1.39 square feet. Converting the net ounces of microgreens to grams and dividing by this area provides a density measure useful for scaling production.