Introduction
Determining the best grow time for each crop can be a daunting task, and I’m not about to make it any easier. If you’re new to growing microgreens, I recommend starting with the grow times listed in this article - Microgreen Yield Cheatsheet. Today's article will bring together ideas from various other blogs to build a framework for making your own grow time determinations. In short, we want to balance three variables. We want to maximize yield per tray to increase the revenue per tray. We want to grow a quality product that’s in line with customer preferences. Finally, we want to maximize the total number of trays moving through our farm to maximize net profit.
Balance Yield, Consistency, Quality, & Profit
1. Maximizing Yield per Tray
The goal of every business owner is to increase the revenue generated for every dollar spent on COGS. As a reminder, COGS stands for "cost of goods sold." In a microgreen farm, the main COGS are seeds, soil, packaging, labels, and fertilizer. If we want to get technical, which I usually do, this is referred to as your gross margin ratio (GMR). A higher GMR means you’re producing more revenue for the same spend on COGS. For example, let’s say we have two farmers who both spend $3.50 on COGS per tray of microgreens. Both charge their customers the same price per ounce - $2.50. Farmer A yields eight ounces per tray, or $20.00 in revenue. Farmer B only yields six ounces per tray, or $15.00 in revenue. Farmer A has a much better GMR. We want to be like Farmer A, which we can achieve by reducing our COGS, increasing our yields, or both. We can increase our yield by (i) increasing the sowing density, (ii) using fertilizer, or (iii) extending the grow time. There are infinite other options, but these are three big levers. The obvious answer is to increase the grow time. The marginal cost for the grow lights for a few additional days is negligible. In this scenario, the COGS remain the same, but the yield should be bigger. A higher yield means more revenue, assuming the final product is still high quality. There’s our answer, right? Continue increasing the total grow time until you see a plateau in yield. Not quite. Remember, we have to balance maximizing the yield per tray with the other two variables. At some point, quality will suffer as you extend the grow time. The plants will get too big, diseased, or nutrient-deficient, all of which harm quality and conflict with consumer preferences.
2. Crop Quality & Customer Preferences
Different customer segments have different preferences for their microgreens, but we can assume they’re all closely related. Chefs, wholesalers, retailers, and home consumers all want microgreens with a long shelf life. Everyone also wants bright colors, rich flavors, and intense aromas. The main difference is that not everyone cares that much about nutrient density, but we’ll ignore that for now. What about size? Microgreens occupy a specific niche distinct from baby greens and other petite produce for a reason. Although there’s an acceptable size range for microgreens, most consumers want them to be “micro.” Even if you could maximize the yield per tray by extending the grow time and growing a bigger crop, at a certain point, your microgreens will be too large to be ideal. All else being equal, like sowing density, eventually your microgreens will run into issues with nutrient deficiencies and overcrowding. Even if you solve the former by adding fertilizer, the latter will constrain your crops. You could reduce the sowing density to mitigate overcrowding and competition, but that can hurt the overall yield. So, even if you extend the grow time and never run into a yield plateau, you will see quality plummet. Clearly, there’s a sweet spot between increasing the grow time to increase the yield and customer preferences. The two variables are at odds with each other.
3. Total Tray Throughput
For this variable, we need to assume you don’t have unlimited space. Let’s assume you’re at or approaching capacity in your current building. Here's a quote from another article - Maximizing Your Microgreen Tray Throughput.
“In the journey to maximize the productivity of a microgreen farm, understanding the relationship between potential revenue per tray and the total potential profit from the farm is paramount…Growing microgreens for a longer period typically increases yield per tray, but it also requires more space in the farm—a valuable resource that's often limited. To maximize profitability, it's crucial to grow trays just long enough to achieve a high yield without unnecessarily extending grow times that require additional space.”
In a simplified way, you have two options when space is limited. First, you could have fewer trays with a longer grow time, each tray producing a higher yield and more revenue. Alternatively, you could have more trays with 2/3 the grow time, each tray producing 2/3 the yield and 2/3 the revenue. However, in the latter scenario, you get to cycle twice as many trays through your farm each month. The total spend on COGS is higher in the second scenario, and the gross profit per tray is lower. Despite these two negatives, you’ll actually generate more profit for your farm because of the greater throughput. Therefore, total tray throughput works against our first variable, longer total grow times.
Summary
So, how do you determine the best grow time for your microgreens? There is no simple, clean answer, but here’s my suggestion. Start with the grow times in the cheatsheet we linked in the beginning. Grow your crops using the same sow density, grow time, and overall regimen for a few weeks to determine a baseline. Collect data on yield per tray and subjective quality parameters, like smell, taste, and color. Get input from chefs and friends about their preferences. With this baseline data in hand, start testing one new variable. Two easy and high-leverage variables to start with are grow time and sow density. See how changes in each variable affect quality and yield. If you see an improvement across both yield and quality, keep testing that variable until either quality or yield suffers. Find the sweet spot, stop changing that variable, keep everything the same, and take data for a few weeks. After a few weeks, you have new baseline data. Start manipulating a different variable and watch what happens to yield and quality. Repeat this process with any variable you want. Eventually, you’ll find a sweet spot that considers all the main variables. Congrats, you just determined the best grow time for each crop.
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