Planting onion seeds is a straightforward process, and here's a guide to help you get started:

1. Seed Selection: Choose high-quality onion seeds from a reliable supplier. Consider the onion variety that suits your preferences and local climate.

2. Timing: Onions are typically grown from seeds started indoors. Start onion seeds indoors 8-10 weeks before the last expected frost in your area. This timing allows the seedlings to be ready for transplanting when the weather is suitable.

3. Seed Starting Mix: Use a well-draining seed starting mix to sow the onion seeds. Plant the seeds about 1/4 to 1/2 inch deep in individual cells or seed trays.

4. Temperature and Light: Maintain a warm environment for germination, ideally around 65-75°F (18-24°C). Once the seedlings emerge, provide them with plenty of light. Consider using grow lights if natural sunlight is insufficient.

5. Thinning: When the onion seedlings are a few inches tall, thin them to allow proper spacing. This helps prevent overcrowding and ensures healthy bulb development.

6. Transplanting: Transplant the onion seedlings outdoors once the soil is workable and the threat of frost has passed. Space the transplants according to the recommendations for the specific onion variety.

7. Soil Preparation: Onions prefer well-draining, fertile soil. Work in organic matter, such as compost, to improve soil fertility. Aim for a slightly acidic to neutral pH.

8. Planting Depth: Plant the onion seedlings at the same depth as they were in the seed trays. Press the soil gently around the roots.

9. Watering: Keep the soil consistently moist but not waterlogged. Onions need regular watering, especially during dry periods.

10. Mulching: Apply a layer of mulch around the onions to help retain moisture, suppress weeds, and maintain a more even soil temperature.

11. Fertilizing: Onions are light to moderate feeders. Fertilize sparingly with a balanced fertilizer during the growing season. Too much nitrogen can lead to excessive foliage growth.

12. Harvesting: Harvest onions when the tops have fallen over and started to dry. Allow the onions to cure in a dry, well-ventilated area for a few weeks before storing.

By following these steps, you can successfully plant onion seeds and cultivate healthy, flavorful onions in your garden.