Plant the onion bulbs 2 to 3 weeks before last frost date. Fill the 13 inch round container with soil to one inch below the rim. Plant bulbs 3 inches apart one inch deep in the container. Cover with soil. When planting, separate the bulbs by size. The larger bulbs will mature early and should be harvested as green onions. Believe it or not, the smaller bulbs will actually grow larger and can be harvested later when the onion top starts to fall over. You can keep them in the soil for a long time.
Wash them gently and let them cure in the sun for a few days before storing or using.