How much seed should you put in each of the 5×5 inch trays?
It depends (you have heard that from me before!).
Start with a smaller amount of seeds per tray when you are first experimenting with a new microgreen variety. Instant success often depends on your growing conditions. For example, someone living in a desert region with low humidity can grow microgreens at a denser rate than someone in an area of high humidity, high heat. The reason is that unlike garden plants, microgreens are planted closely together in a tray. The denser they are planted, the more potential for crowding issues. Mold requires constant moisture and little air flow. Those in dry, cool areas will have little problem with mold. Those in southern states or areas with lots of humidity may need to adjust the density and airflow in their growing space to prevent mold.
Using the microgreen seed chart
In this chart, there are two numbers for each seed. The first number is the amount of seed you should begin with. If your microgreens grow well, do not seem crowded, and show no mold issues, then gradually increase the amount in your trays to the larger amount.
The following are the most popular microgreen seeds. Once you feel confident with this chart and the listed seeds, experiment with other seeds, judging amounts by the size of the seed. The smaller the seed, the smaller the amounts you will sow in your trays.
Tbsp- US measuring tablespoon- level, not heaping
Tsp– US measuring teaspoon- level, not heaping