The first factor is TEMPERATURE

I try to keep my grow room right around 73 degrees Fahrenheit. My plants grow plenty fast at this temperature and it's high enough where the water can evaporate quickly, but not too high where I get mold. It's also not low enough where it causes condensation or slows down my plant growth.

The second factor is HUMIDITY

Microgreens cause a lot of excess moisture to be in the air, so this is a factor that must be controlled. If your grow room is extremely dry, your growing medium to dry out more rapidly, and the plants will become dehydrated and fall over. This will require you to water your plants multiple times per day, which isn't ideal and is quite inefficient. Too high of a humidity and your growing medium will hold too much water, increasing your chance of overwatering your microgreens trays. Additionally, a higher humidity in your grow room will reduce the ability for evaporation off of your plants, causing them to remain wet. If your microgreens are too wet while they grow, they're will start to rot, becoming mushy and nasty. If your microgreens are too wet when harvesting, they will be a lower quality product with a shorter shelf life. I try to keep the humidity in my grow room right around 35-40% by using a dehumidifier.

The last factor is AIRFLOW

Airflow is critically important. It keeps the air and everything in the air moving through your grow space so nothing like mold can settle and multiply. Airflow prevents the air from around and within your microgreens tray from becoming stagnant. This helps the plants get rid of excess moisture and prevents them from being in an environment that's conducive to disease. The plants don't need fans blowing on them at full blast… Just make sure to keep the air moving through your farm space and you'll be just fine!