when time does onion grow
How to Grow Onions: Plant onions sets (small bulblets) 3 to 4 months before the time you want to harvest mature bulbs; plant sets 3 to 4 weeks before you want to harvest immature green onions. Start onion seeds indoors 4 to 6 weeks before the average last frost date in spring, and transplant them into the garden as soon as the soil can be worked.