Onions need full sun and well drained garden soils to do their best. All onion types can be started from seed. Seed can be sown indoors about 4 to 8 weeks before transplanting. Seed can also be sown directly into the garden as soon as the ground can be worked. Onions can also be grown from sets.
Onion sets are small, dormant onion bulbs that are ready to be planted outdoors.
Their best use is for green onions. Harvesting the green onions is a good way of thinning the row so the remaining onions are 3 to 4 inches apart. Onion transplants can be purchased at garden centers and through mail order catalogs. Plant transplants 3 to 4 inches apart and about 1 inch deep. Onions are shallow rooted.