How to Grow Green Onions

Growing Green Onions from Seed or Sets

Choose a type of onion to grow. Green onions, or scallions, are the green shoots that come up before an onion bulb begins to form. They are essentially immature onions. Look for a hearty scallion seed, such as the species A. Welsh onions, or simply choose your favorite white, red or yellow onion to grow. If you'd prefer not to start the green onions from seed, choose red, white or onion "sets" to plant. These look like bare-root mini bulbs that come bound with twine or rubber bands. You can pick up a few sets to use as scallions, and let the others mature into onion bulbs.

Prepare a planting bed. Choose a spot in your yard or garden that gets full sun and has soil that drains well. Till the dirt to a depth of 12 inches and work in compost, blood meal or another organic material to enrich the soil with nutrients. This will ensure that the green onions grow strong and healthy, and continue to produce shoots throughout the growing season. Be sure rocks, sticks and weeds are cleared away before you till and work the soil. You can till the soil using a garden rake if you're working with a small patch. For a bigger area, buy or rent a soil tiller to make the job easier. If you just want a few green onions, you can prepare a pot with a compost-rich potting soil instead of planting them in the ground.

Plant the seeds or sets. As soon as the soil is workable, about four weeks before the last frost, it's time to plant the seeds or sets you have ready. If you have seeds, sow them thickly about 1/2 inch deep in rows spaced 1 foot (0.3 m) apart. If you have sets, plant them root-side down 2 inches apart and 1 inch deep, in rows 1 foot (0.3 m) apart. Water the garden bed thoroughly. The onion seeds will germinate when the soil is anywhere between 65 to 86 degrees Fahrenheit (18.33 to 30 degrees Celsius). It may take up to a month for onion seeds to germinate. If you live in a cold climate with a late spring, you can start the seeds indoors about eight weeks before the last frost. Plant the seeds in peat seed starter pots and keep them well-watered. Put them in a warm, sunny room to during the germination period. When the ground outside is warm enough to work with, transplant the seedlings to the garden or a larger pot.

Thin the plants if necessary. When the first green shoots begin poking up, determine whether to thin them to give them each a bit more room. Green onions grow well in bunches, but for best results the mature plants should be spaced 2 to 3 inches apart. Take a look at your garden bed and remove weaker seedlings if necessary.

Mulch between the seedlings. Cover the soil around the seedlings with grass clippings, pine straw or fine pieces of bark. This will prevent weeds from growing and keep the soil evenly moist. If you're growing your green onions in a pot, you can skip this step, since weeds won't be an issue and you can more easily control the moisture level.

Keep them well watered. Green onions need evenly moist soil throughout the growing season. Provide the onion plants with about 1 inch of water per week. For optimal plant growth, the soil does not need to be soggy, but it should be moist. Water the garden bed every few days, or when it begins to look dry and dusty. Another way to determine whether the onions need watering is to test the soil conditions. Insert your finger, up to the second knuckle, in the soil close to where the plant is. If you feel that the soil is dry, water it. If you think the soil is wet enough, don't worry about watering, and repeat the test again in a few days. If your area has received rain recently, you may not need to water.

Harvest the green onions when they have matured. After three to four weeks, the green shoots will be 6 to 8 inches long and ready to eat. Harvest them by pulling the entire plant from the ground. The plant will not yet have formed a bulb. Both the white and green parts of the onion are flavorful. If you want to let some of the plants mature into storage onions, simply leave them in the ground. The bottom of the plants will begin to form a bulb, which will be ready for harvest in the fall. If you only want to use the green part of the onions, and not the white part close to the roots, you can use a pair of scissors to simply cut off the green tops. Leave an inch or two of growth. The onions will continue to grow, and you can harvest the greens again once they're 6 to 8 inches long. Note that they will become stronger-tasting as the plant matures.

Growing Green Onions in a Pot Indoors

Pick out onion sets to grow. Choose red, white or onion "sets" to plant. Available at your local nursery, these look like bare-root mini bulbs that come bound with twine or rubber bands. Any type of onion sets will make excellent green onions, and they all grow well in pots indoors.

Prepare a pot with rich potting soil. Green onions grow best in very rich soil, so choose a potting soil that has been enriched with compost - or mix in your own compost with standard potting soil. Fill the pot to within a few inches of the top. Water the soil to prepare it for planting. Be sure the pot you use drains well, so that the soil never gets waterlogged.

Plant the sets. Plant each onion 1 inch deep, pointing the root side down. Gently pat soil over the top. Space them 1 1/2 to 2 inches apart to allow them a little room to form roots without crowding each other. Water the onions and place the pot in your sunniest window. You can grow green onions indoors any time of year, as long as you maintain the correct conditions. The onions need full sun, so they should be placed in a window that receives light for most of the day. Be sure the temperature never drops below freezing. Keep the soil evenly moist. Water every few days, or when the soil seems to be getting dry. Don't overwater the onions, though - the soil should be moist, but never soggy.

Harvest the greens when they're 6 to 8 inches tall. After a few weeks, the green tops will emerge and grow. Either pull the plants from the pots to use the whites and greens, or use a scissors to trim off the green tops and leave the bulb to continue growing. If you leave the bulb in the pot, you should get at least one more harvest before it stops producing.

Growing Green Onions in a Glass Jar

Save your green onion bulbs. Next time you buy green onions to use in a recipe, save the white part with roots and eat only the greens. You can grow more green onions using only the leftover roots - and next time you want to add flavor to a dish, you'll have your own home-grown green onions on hand. Any green onions bulbs will work, but you might have the best luck if you use green onions that were grown nearby. That way you know they'll grow well in your climate. Try starting with green onions you bought at the farmer's market, since they were probably grown in your region.

Put them root-down in a glass jar. Any type of clean glass jar will do. Just make sure the glass is clear, and not tinted, so that the sun's rays can easily reach the onions inside. Put in as many green onion rots as you'd like - just make sure the roots are facing down, so that the greens grow up and out of the jar.

Add water and sun. Pour in enough water to cover the bulbs entirely. Set the jar in a sunny window and wait for the magic to happen. Within a few days, you should see the roots starting to get longer. Tiny green shoots will emerge from the bulbs and begin growing upward. Keep the jar filled with enough water to cover the white part of the onions.

Harvest the greens. Once they're 4 to 6 inches long, they're ready to harvest. Remove a green onion from the jar and chop off as much as you want - or use the whole thing. If you just need a handful of chopped scallion, you can return the bulb and roots to the jar to continue growing. You should be able to harvest the same onions two to three times before they stop growing. If you want to continue growing onions year round, then put some rocks and pebbles in the bottom of the jar. Then, place soil over the rocks and pebbles and plant the bulbs in the soil.