When to Harvest Green Onions

Green onions grow from the same seed and bulbs as regular onions, but are planted closely together so they develop tall foliage stalks instead of a large bulb. The stalks of green onions have a milder flavor than bulb onions and they can be used fresh or cooked in a variety of dishes. Harvesting at the right time ensures the stalk has developed and has the best flavor.

Grow green onions from either sets or seeds. Sets are small onion bulbs that begin growing as soon as they are planted, so there is no need to wait for seeds to germinate. Sets reach harvesting stage more quickly than seed-grown green onions. Plant sets or seeds in the fall in warmer climates that experience mild winters. Plant sets in spring in colder areas that experience winter freezing. Seeds will not reach maturity in cold climates, unless you start them indoors in late winter, then transplant them outside in spring.

Green onions are ready for harvest once the green tops are between 6 and 8 inches tall and the bulbs are an inch or less in diameter. Both winter- and spring-planted onions are ready for harvest in fall, but in mild climates, you can continue growing and harvesting throughout winter. In colder areas, all the onions must be harvested before the ground freezes.

Set-grown onions and fall-planted seed onions can be harvested earlier in the summer, though the onions won't be as large as those allowed to reach full maturity. Spacing the onion sets farther apart allows for more rapid bulb formation. Harvest these onions in early to midsummer once the bulbs are approximately 2 inches in diameter. Use both the bulb and the green top in stews and soups.

Loosen the soil around the base of the green onion bulbs with a handheld garden fork, then lift the onions from the bed. Peel off the outer leaf on the stalk, which is usually discolored, revealing the green inner leaf and the small white bulb. Trim off both the top of the leaf stalk and the roots from the bottom before using the green onions. Green onions can be stored for three to five days in the fridge. Harvest the stalks as you need them, since they have such a short shelf life.