Onions grow best in sun and in well drained soil with a pH of 6.0 to 6.5. Muck soils are ideal.

Onions are started from seed, sets or transplants, but seed takes longer. Plant sets or transplants 3/4 inch deep and 1 inch apart then thin to 2 to 3 inch spacings before crowding occurs. Thinnings may be used as green onions.

Bulbs form better in cool temperatures. Green onions can be grown from seed or small transplants. Onion rows are spaced 16 inches apart. If no other fertilizer was used apply 2 cups 5-10-10 per 25 feet of row. Work the fertilizer into a 1 foot wide band where planting will be done. Onions are low plants with sparse root systems so keep weeds under control.

Harvest when the tops fall over and dry up. Spread out the harvested bulbs in a dry area to cure for several days. Use injured bulbs, don't try to store them. The tops of slow maturing plants may be broken over but don't bruise the neck of the bulb in the process.

Hot onions are due to insufficient watering. Flowering may occur if the sets were too large or stored improperly. Remove the seed stalk before it is 6 inches tall.

Source: Michigan State University Extension.