Trays can be either stacked with a gap between, to allow light to get to the sprouts, or without a gap to create a damp dark environment that is ideal for germination and growing beansprouts (click on the ‘view larger images’ button above for details). Because the trays are heavier than plastic varieties, the weight of an upper tray on beansprouts below helps to make the sprouts thicker and stronger as they push up against it. The natural terracotta trays also allow greater ventilation and help to prevent mould from developing.