Onion Seeds,
Australian Brown

Start seeds indoors three months before the last expected frost date in spring. Onions begin slowly, so this early start allows for adequate growth before transplanting. Transplant acclimated, stocky seedlings into the garden 4-6 weeks before the last frost of spring, as onions can tolerate light frosts. For best results, check your local area’s frost-free dates to plan your planting schedule. 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 trays or directly in the ground if the conditions are frost-free. Keep the soil temperature around 60 F for best germination results. Space seedlings 4-6 inches apart, with rows 12 inches apart, to give the bulbs enough room to develop.

Apply a balanced fertilizer every 2-3 weeks, as onions are heavy feeders. Keep the soil evenly moist but not waterlogged. Weed regularly and mulch to conserve moisture and reduce weed competition. When the tops begin to yellow and fall over, stop watering to allow the bulbs to mature before 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.