How to Start Onion Seeds

Loosen the soil in an area of the garden that receives full sun. Mix in with organic compost two weeks before sowing the seeds. If you need to improve soil drainage, also add about 2 inches of pea gravel to your planting bed and blend it in well. Rake your planting bed to a smooth surface, keeping the soil loose.

Sow onion seeds 1/2 inch deep. If you're planting more than one row, space them 18 inches apart. Water the soil thoroughly with a gentle sprayer or a soaker hose, as strong jets of water might dislodge the seeds. Through the growing season, don't let your planting bed dry out between waterings.

Thin onion seedlings to 5 inches apart. You can either eat the plants you pull out or replant them in a different spot to let them fully develop. Trim back the tops of transplanted plants, about halfway. In addition, pull any weeds you see and continue to weed the bed by hand regularly.

Mulch around the base of the plants after the seedlings appear on the surface. This helps conserve moisture and reduce weeds.

Control pests and disease. According to the Ohio State University Extension Service, thrips, onion maggots, downy mildew, neck rot, pink root and smut can all attack onion plants. Since onions are a food item, avoid synthetic pesticides. Instead, get help at your local extension office identifying the problem and finding a natural solution.

Harvest your onions after the tops become yellow and dry. Dig underground with a trowel or shovel and take the onion bulbs out. They're ready for eating. To store onions, let them dry on the ground for two days, then brush the soil off, remove the tops and necks, and put them in a cool, dark, well-ventilated area.