This was a really fun experiment and something that I want to sell at Farmers Markets. You can really get creative with these.
I used a technique from a microgreen grower in Australia named Pepe.
I will embed the youtube below.
I washed the containers in a very light bleach solution first as you want to avoid any possibility of a fungus invading your grow.
Then filled up the containers to the top with a mix of potting soil and coconut coir, but you can just use potting soil also. Also putting holes in the bottom so it could soak up water and get nice and moist. I bottom water micro greens as much as possible. You can knock them down with too hard a spray or a stream of water. Then I tamped down the soil so it was nice and flat. What Pepe said in the video is you want to get good contact with the seed and the soil and moisture so you need to get it to the brim so when you put the weight on it pushes the seed into the soil.
I did Red arrow Radish , Arugula, Amaranth and Broccoli.
Then I put another black tray like they are sitting in and put it on top to act as a weight. You can also just put foil on top and then use something like a book to force the seeds into the soil.
Good Germination I was very happy! I took the weight off in the morning and then covered the trays with another 10 x 20 black tray. This is also called a blackout dome. The idea is the plants will grow taller looking for light. If you don’t the greens are too short to cut. By the end of the day the plants had grown this much.
The radish, and arugula are almost ready to uncover and put under the light.
The 5th day the radish was ready to go under the lights, it was nice and tall. The Arugula was not as tall but still good height. The Amaranth was nice as you can see, and I wish I would have harvested it the next day as it started to die off. Amaranth can be tricky.
The cups sustained well for another week until I had to leave Oregon.
They look very nice as a houseplant as well.