12 Cell Plastic Trays with Holes. Microgreens. Gardening. Wheatgrass. Seed Starting. 12 Cell plastic trays fit any 20x10 microgreens watering tray and come pre-cut with easy and large drainage holes. Each tray is 5x3 inches long and wide and comes perforated for easy propagating and seed starting without any worry of mess. 12 cell trays easily fit 10x10 watering trays as well when split in half, comfortably fitting 6 individual 3x5 trays per 10x10.