Seedling trays or seed trays are made up of foldable plastic material. There are cells (holes) throughout the trays. These cells should be filled with sowing medium like soil, cocopeat or sand. Depending on the type of plants, 2-3 seeds are sown in each cell. Trays are watered regularly as the seeds germinate. Young seedlings can be kept in these trays safely for 3-4 weeks under semi-shade till they are ready to be transplanted on the field or in bigger containers.