20 Row Seedling Flat &ndash; Seed Tray - Growing - Seed Starting - Case of 50 This 20 Row Seedling Flat is great for seed sowing. Drain holes so no over watering when using this 20 Row Seedling Flat. Case of 50 each Seedling Trays made of very durable plastic and reusable. 10 inch x 7/8 inch x 1 1/4 inch deep rows for easy seeding. Overall dimensions 21 inches x 11 inches x 1 1/4 inches. Row allow you to separate different varieties of seed planting.