Updated: May 6, 2020
There are extra factors with microgreens that may cause things in the germination stage to fail, so troubleshoot possible problems and their solutions. Double check your temperature to make sure things aren't too cold or hot.
Germination and darkness
Make sure when you germinate microgreens seeds that they are in darkness. If you use humidity domes, make sure the domes have top vents. Make sure you cover properly but don't force the dome on. Even though the seed is covered with a humidity dome, make sure your tray is in darkness. The seeds need to be kept away from light. As soon as the seeds open it is necessary that the tray receive light.
Room temperature water
Never use water directly from tap. Always let it reach room temperature. Cold water can shock microgreens because it quickly reduces the environment temperature of the medium (microgreens pad). The same goes for seed germination, don't stick seeds in cold water and don't moisten seeds with cold water. Even when you feed your microgreens you should let the water reach room temperature. Another thing is that you need to check your own water supply to determine its quality. In most cases chlorine in water won't cause issues with your microgreens but if your water isn't very clean or pure then you can't expect your microgreens to use it well either. In each case you need a way to generate clean water which can do by boiling it and letting cool to room temperature.
Water soaking seeds
Some of the big microgreens seeds may need to undergo soaking before they germinate. In this case the pea seeds should be placed into a room temperature bowl of water for 24 hours before being removed and place on the germination medium. This is not recommended unless you have trouble germinating seeds. If you keep them for too long in the water they might not get air, which they need or the microgreens seed will sour. New seeds tend to survive this method better than old ones, which tend to uptake too much water.
Air is something your microgreens need all time, even in the germination stages. Stale air results in change in the ratio of gases that comprise it and the accumulation of new ones. Over watering can be a huge problem from the day you start to germinate your seeds. It locks out air. There is never a need to turn a microgreens medium into a swamp.
pH imbalances outside of 7 (base) can cause problems. The way to test your pH is to test the medium before you put the seeds on. If you have a pH problem it is best to replace the medium. If you can't then pH up and pH down products can bring medium to a pH of 7, which is recommended.