Start indoors or direct sow?

Start indoors for an earlier harvest, or direct sow once the soil can be worked. They tolerate transplanting well, so indoor starts are useful where springs are short.

When to start Green Onions seeds

For transplants, sow 8 to 10 weeks before the average last spring frost. Direct sow 2 to 4 weeks before the last frost, then make additional sowings every few weeks for a longer harvest.

How to sow the seeds

Sow seeds about 1/4 inch deep in a sterile seed-starting mix, using cell packs or a shallow tray. For indoor starts, several seeds may share each cell, since the seedlings can be planted outside as a small clump.

Germination

Seeds usually sprout in 7 to 14 days. Keep the mix evenly moist, not wet, at about 60 to 75 F.

Seedling care

Give seedlings strong light for 12 to 16 hours daily and water when the mix surface begins to dry. Provide airflow and good drainage to prevent damping off, and trim overly tall seedlings if needed.

Transplanting & hardening off

Harden seedlings off for 5 to 7 days before planting them outside around the last frost date or shortly before. Set clumps about 1 inch deep and 2 to 3 inches apart, separating seedlings only if you prefer individual plants.

Tips

Use fresh seed, because onion-family seed loses viability relatively quickly. Keep plants consistently watered for tender, mild stems.

General seed-starting guidance for US home gardens; timing depends on your local frost dates and variety. Page updated Aug 4, 2026.