Will this work well with shallow mircogreens
Sure does! We recommend using hemp or some other mat as the media in a combination of a flood & drain.
Will 10x20 flats rest on the lip suspended, or sit down in the tray with the bottom resting on the inner bottom surface? Ill be using this for bottom watering shallow microgreen trays, so it won't work well if they are suspended by the top lip, eh?
The trays will rest on the surface and the water will come in through the drain holes as you bottom water.