How to Regrow Green Onions in Soil or a Glass of Water

Green onions, also known as scallions (Allium cepa), are members of the allium family (to which garlic and onions belong) that have long, green leaves, as well as stiff, white stalks close to the root, and stringy root hairs. Also known as “bunching onions,” green onions grow in bunches and are harvested young. Unlike spring onions and shallots, green onions don’t contain a large, swollen bulb at their basal plates. The white base of green onions has a sharp, peppery flavor, while the leafy, green parts have a grassy and fresh flavor.

Regrowing green onions at home can help save you money and cut down on food waste, because you use the bulb which would normally be discarded to produce new growth. Fresh green onions are especially quick and easy to grow at home and don’t require much care to yield new specimens within a couple of days. Placing the white stalks of green onions in a cup of water in a sunny place can yield new green onions within five days.

The easiest way to regrow green onions is to place them in a cup of water in a sunny place in your home. Follow these steps to regrow green onions in a simple glass of water.

1. 1. Snip off the green stalks. Cut the green tops off of your onions, leaving two to three inches of the white base intact (where the stubby roots are). You’ll grow your new onions from these white pieces.
2. 2. Place the roots in a glass of water. Fill a small, narrow glass with tap water, and place your root cuttings inside, root side down so that they are standing upright. Cover the cuttings with enough water to cover the roots, leaving a little bit of the top exposed.
3. 3. Keep the glass by a window. Place your glass in a sunny spot like a windowsill to provide your onions with enough sunlight over the next couple of weeks.
4. 4. Replace the water. Change the water containing your onions every two to three days. As your onions grow, their roots and leaves will become long enough for you to harvest the green stalks. You can also replant these root cuttings into soil after you’ve grown a batch or two of onions.

Growing green onions in a glass of water will yield new onion crops quickly, but the buds will only work for up to five new crops. Planting in soil enables you to grow an essentially endless supply of green onions that are generally larger than the ones you’d grow in a glass. Here is how to plant green onions in soil.

1. 1. Snip off the green stalks. Take a green onion and cut off the green stalks so that there are at least two inches of the white part where the root is. This will be your cutting.
2. 2. Prepare your planter. Prepare a growing space (either a container or a garden bed) with potting soil. Poke holes in your soil that are a half-inch to three-quarters of an inch deep, with one inch of spacing between them.
3. 3. Plant your scraps. Stick the root ends of your cuttings into the holes, gently compacting the soil to keep the rest of the cutting upright. Water your cuttings and leave them in a place that gets full sun for a few days (or weeks) until they sprout new green shoots and leaves from the tops.

Regrowing your own green onions is an easy DIY gardening project that even novice gardeners can master. However, there are a few tips you can follow to set your green onions up for success.

1. 1. Leave an inch behind when harvesting. If you plan on regrowing your green onions repeatedly, leave about an inch of cutting behind when you harvest your onions. New onions will continue to grow from these pieces
2. 2. Use soil and fertilizer for thicker plants. Green onions can grow well in water, but they grow larger and for longer periods of time in soil. Sprinkle a bit of high-nitrogen fertilizer or compost in the soil around your onions from time to time to encourage thick, new growth.
3. 3. Keep the roots moist. Green onions need plenty of moisture and air circulation to thrive. Keep their soil moist, but make sure it drains well to eliminate the chance of root rot.

Grow your own garden with Ron Finley, the self-described "Gangster Gardener." Get the MasterClass Annual Membership and learn how to cultivate fresh herbs and vegetables, keep your house plants alive, and use compost to make your community—and the world—a better place.