How to Grow Onions from Onions at Home

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Edible gardening expert Erin Hostetler explains how to plant and grow your very own onion plants

Co-authored by Erin Hostetler and Amy Bobinger, BA

Last Updated: December 26, 2025 Fact Checked

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• Rooting a Cutting
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• Planting the Cutting
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• Maintenance & Harvesting
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• Can you plant a sprouted onion?
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• Video
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• Q&A

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Onions are as simple to grow as they are delicious to eat in a variety of dishes. And, as long as you have another onion on hand, you don't need to grow them from a seed. By chopping the bottom of an onion off and planting it in soil, you can grow your own onions from cuttings. We’re explaining how to cut, root, and plant an onion to get the biggest bulbs, with tips from edible gardening expert Erin Hostetler and garden specialist Steve Masley.

How do you grow an onion from an onion?

Edible gardening expert Erin Hostetler says to leave about a 2-inch (5 cm) piece from the bottom of the onion, which is where the root hairs grow. To plant the onion, follow these steps:

1. Place the onion in water so only the roots are submerged.
2. Transfer the onion to soil after 3–4 days, when new roots emerge.
3. Place the onion roots down in a container of well-draining potting soil.
4. Keep the soil moist but not drenched.
5. Divide the shoots after a few weeks to get bigger bulbs.
6. Harvest the onion bulb when the green shoots wilt and turn brown.

Steps

Section 1 of 4:

Rooting an Onion Cutting

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1. 
   1
   Cut off the bottom 1-2 inches (2.5-5 cm) of the onion. “To grow a new onion bulb from an onion bottom, leave about 2 inches of bulb attached to the bottom of the onion,” says Hostetler. She explains that “the bottom of the onion is the side where you see the ‘root hairs.’" Simply place your onion on a cutting board and use a sharp knife to cut a thick slice from the bottom of the onion, being sure to leave the root section intact.

   • If you're growing the onions outside, start your cuttings in early spring. For onions grown indoors, any time of the year is fine.
   • You can try this with most onion varieties, including those purchased at the store.
   • This technique works best with a fresh onion.
   • Use the top section of the onion for cooking, or compost it if you’re not going to eat it.

   Meet the wikiHow Experts

   Erin Hostetler is an edible gardening expert and the owner of The Patio Farmer. She has over 10 years of experience working on farms and growing food.

   Steve Masley is a garden specialist who has designed and maintained organic vegetable gardens for over 30 years. He is the founder of Grow-It-Organically, a website that teaches the ins and outs of organic vegetable gardening.
2. 
   2
   Peel the outer skin off and let the cutting callous for 12–24 hours. Carefully remove the papery outer layer from your onion slide. Then, place the bottom of the onion on a flat, dry surface with the cut side up. Let the onion bottom dry out for up to a day until it is calloused and dry to the touch.

   • Sometimes this only takes a few hours. Once the cutting is dry and slightly shriveled, it’s ready.
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3. 
   3
   Suspend the onion over water so just the roots are submerged. Fill a cup, vase, or other small container with water. Rest the onion on the lip of the container so only the roots are touching the water. If the onion itself sits in water for too long, it will turn mushy and rot.

   • If the onion is too small to rest on the sides of the container, push 4 toothpicks into the sides of the onion, spaced evenly all the way around. Then, rest the toothpicks on the container to hold the onion above the water.
4. 
   4
   Let the onion root in water for 3–4 days. Masley recommends leaving the onions in water “until you see some root development.” Once you see white roots growing from the bottom, it’s time to transfer the onion to the soil.

   • Change the water every 1–2 days to prevent it from getting cloudy or smelly.
   • The roots won’t develop much in water, so it’s best to transfer the onion sooner rather than later.
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Section 2 of 4:

Planting Your Onion Cutting

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1. 
   1
   Fill a planter pot with well-draining potting soil. Hostetler suggests using seed starting mix or potting soil. If you’re using a potting mix, choose one with additives like perlite, pumice, crushed granite, or coco coir to help improve drainage. Then, fill a planter with drainage holes to about 2–3 in (5.1–7.6 cm) from the top.

   • Onions need full sun, so Hostetler says to leave your plant in a bright, sunny spot.
   • You can also plant the onion outside in a well-draining garden bed. Just plant it in a spot that gets 12–14 hours of sun a day.
2. 
   2
   Place the onion cutting in the soil and lightly cover it with soil. Dig a shallow hole in the soil, just big enough for the onion to rest in. Then, Hostetler says to place the root end into the soil. Cover it with a thin layer of soil—no more than about 1–2 in (2.5–5.1 cm). If you bury it too deep, the onion won’t grow.

   • If there are any green shoots coming from the center of the onion, be sure not to cover those, or they won’t grow.
   • You can even skip covering the onion with soil, if you’d like. Just be sure the roots are securely in the soil.
3. 
   3
   Water the onion cutting immediately after planting it. Watering the onion cutting helps it adapt to its new environment and grow roots faster. Give your onion enough water that the soil is damp to the touch, but not soaking wet.
4. 
   4
   Divide the onion plant after a few weeks to get bigger bulbs. Once your onions have started producing vigorous, clumping green shoots, dig them up. You’ll likely see several new plants clustered together, sharing a root ball. Use your fingers or a knife to carefully separate the shoots. Be sure each shoot has roots attached to it. Then, plant the individual shoots 1 in (2.5 cm) deep and 4–6 in (10–15 cm) apart in a pot or garden bed.

   • If you leave the shoots growing together, you’ll get a cluster of small onion bulbs. By dividing them, you’ll give each bulb more space to develop, which means you’ll have bigger bulbs at harvest time.
   • If you’re growing onions to harvest the green tops, you don’t have to divide the shoots.
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Section 3 of 4:

Caring for Your Onion

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1. 
   1
   Give your onion about 1 in (2.5 cm) of water per week. Hostetler says it’s important to “keep the soil moist.” Onions need plenty of water when they’re developing bulbs. Check the soil every day—if it feels dry to the touch, water your onion until it feels moist.

   • Onions have fairly shallow roots, so you don’t have to water deeply—just enough that the top 1 in (2.5 cm) or so of the soil is wet.
2. 
   2
   Weed your garden regularly if you’re growing the onion outside. Onions have a hard time competing with invasive plants, and weeds can steal their water and nutrients. Check your garden often for weeds and, if you notice any, pull them right away.

   • Avoid spraying weed killers around the onion, as most herbicides can kill both weeds and garden plants.
   • Check for small insects or other pests on your onion as well. If you see any, spray the onion with a non-toxic, plant-friendly insect repellent.
3. 
   3
   Fertilize your onion every 2 weeks. Fertilizing your onion plant regularly helps it grow large, healthy bulbs. Spray the onion plant at least twice a month with a nitrogen-rich fertilizer until the onion plant's bulb starts to poke from the soil.

   • When the bulb starts poking out of the soil, stop fertilizing the onion until you harvest it.
4. 
   4
   Harvest your onion when the stems brown and fold over. You can typically tell that an onion is ready to harvest because the green tops will turn yellow/brown and start to wilt. You may also see the top of the onion bulb emerging from the soil, or the onion greens may develop a flower.

   • Masley says that if you want to check whether the bulb is big enough to harvest, “just stick your finger in the soil around the top of the plant to see how big the bulb is.”
   • “You can harvest the shoots of the onions whenever you want,” adds Masley, “but if you want larger bulbs, leave them in place. If you have 8 or 10 leaves, you’ll have 8 or 10 growing layers on the onion.”
5. 
   5
   Cure the onions if you’re not planning to eat them right away. Curing the onions will prevent them from spoiling. Leave them outside or in a covered shed for about a week to dry, then transfer them to a wire rack and allow them to dry in a covered place for another 2 weeks. Once the onions are dry, snip the hanging roots off the bottom of the onion (don’t actually cut into the onion itself, though). Also, trim off the green stem about 2–3 in (5.1–7.6 cm) from the top of the onion.

   • If there’s any loose, papery skin on the onion, pull it off.
   • Place the onions in a mesh bag and put them in a cool, dry place. They can last for up to a few months, depending on the variety.
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Section 4 of 4:

Can you plant a sprouted onion?

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1. 
   To plant a sprouted onion, peel away the outer layers to reveal the shoot inside. If you’ve left an onion in the cupboard too long and it’s sprouted, you can plant the sprout to grow new onions. Carefully peel away the layers of the onion, taking care not to damage the shoot inside. Plant the sprouted onion shoot about 1 in (2.5 cm) deep in well-draining potting soil so only the green part is above the soil.

   • Water the sprouts every 2–3 days, and either harvest the green tops or wait for the bulb to develop.

Community Q&A

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• Question

  What time of year do I plant yellow onions?

  

  Community Answer

  Early spring if you're planting outside. Anytime if inside. But early spring is the general rule.

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  How can I collect flower seeds?

  

  Community Answer

  Collect ripe seed on a dry day, as soon as the seed heads (capsules or pods) ripen.

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• Question

  How many onions can you get from one onion head?

  

  Rose Fire

  Community Answer

  In the article it says 1- 6, and you can tell by seeing how many circles are in the center of the onion cut. The circles do not refer to the rings. In the picture above, there are 2 onions that will grow from that one onion head.

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