Onion Seeds,
Flat of Italy

Start seeds indoors three months before the last expected frost date in spring. Transplant acclimated, stocky seedlings into the garden 4-6 weeks before the last frost of spring, as onions can tolerate light frosts. This is an intermediate-day onion, best suited to the middle band of the country; it is not a long-day type for the far North. If you're not sure how to find your first and last frost dates, consult our blog post 'Our Experts Answer Questions, Share Resources.'

Sow seeds 1/4 inch deep in seed-starting trays filled with nutrient-rich, well-draining soil. Germination typically takes 7-14 days at around 60 F. When seedlings are 4-6 inches tall, transplant them into the garden, spacing them 4-6 inches apart with 12 inches between rows. Enrich the soil with compost or well-rotted manure before planting for even better results.

Flat of Italy onions are heavy feeders. Fertilize every 2-3 weeks with a balanced fertilizer or compost tea. Keep the soil evenly moist but be careful not to overwater. Remove weeds regularly. When the tops begin to yellow and fall over, stop watering and prepare for harvest.

• Onions will cross with other onions, and occasionally they will cross with scallion types like Welsh onions and Hi Shi Ko bunching onions. Onions will never cross with leeks, chives or garlic.
• If you are growing types that will cross, try to isolate varieties by at least several hundred feet or ideally up to one mile.
• Onions are a biennial seed crop, so you will need to overwinter your first-year roots, ideally by digging them up and storing them for the winter. Replant in early spring, and allow onions to shoot up spikes of purple flowers.
• Let seeds become dry on the plants. Pick seeds when they are hard and dark black, then bring them indoors to finish drying.
• Once dry, separate the seeds from the husks or leave them on and plant them husks and all.