★ How to Plant a Sprouted Onion ★
Quick Answer: Yes, you can plant a sprouted onion and grow new onions from it. Gently peel away the outer layers, separate the individual onion sprouts, making sure each has some roots attached, then plant them about 1 inch deep and 4 inches apart in a sunny spot. Keep the soil moist but not soggy. In about 3 months, each sprout can grow into a new onion!
If you have an onion sprouting in your pantry, don't throw it away! One sprouted onion can often be separated into multiple plants, giving you two, three, or sometimes even more new onions.
I've used this method to regrow grocery-store onions in my own garden, and readers have been successfully following these steps since I first published this tutorial in 2020.
Check out the step-by-step tutorial, below.
Step 1: Peel the sprouted onion.
To get to the part of the onion you can plant, you need to peel away the layers of the onion bulb, all the way down until you get to just the clump of green sprouts.
Tips:
- If your onion has sprouted, chances are some of the outer layers will be soft and may be starting to rot. If not, you can still eat the outer layers of onion that are not rotten.
- I don't use a special tool for this step. I just peel the layers off with clean hands. Using a knife may cut into the sprouts.
Step 2: Separate each onion sprout.
Carefully separate each sprouted section, making sure each one has roots attached.
Tips:
- I use a serrated kitchen knife but any knife will work.
- Ensure that each sprout has some roots attached.
Step 3: Plant your onion sprouts.
Your onion sprouts will survive for up to 3 weeks before you need to plant them. Store them in a cool, dry place. Letting them dry a little before planting is ideal to prevent rotting.
Tips:
- Do not soak or store onion sprouts in water before planting. This can cause rot.
- Plant onion sprouts in full sun. Onion plants require 12+ hours of direct sunlight a day.
- Loose soil allows the onion bulb to grow.
- Onion plants don't need to be buried very deep. Plant each sprout just 1" into the ground and space them at least 4" apart so the bulbs have room to grow.
- Planted onion sprouts will take about 3 weeks to look perky.
Step 4: Care for your onion plants.
Water and weed around your onion plants as they grow. Fertilize as needed.
Tips:
- Onion plants prefer to be watered in cycles rather than every day. Water onions about once a week unless the soil and plants start to visibly look too dry. Over-watering can cause rot.
- Fertilize your soil. Onions need nutrients to grow so make sure to offer them rich soil. You can use organic (manure, compost, etc.) or store-bought fertilizer to ensure your soil has the nutrients it needs to grow to its full size. Read more about how to test your soil for acidity.
- Onions need well-drained soil. Standing water can cause rot.
Step 5: Harvest your onions.
Onion plants should grow for about 3 months to reach optimum size which is when the bulb reaches the size of a baseball. You will be able to see the top of the onion as it grows and can get a good idea of its size without digging it up. Harvest by pulling the onion out of the ground and then brushing them to remove dirt.
Tips:
- You do not want your onion plant to flower. If it does, the bolting process has started and the bulb will not continue to grow. You can still harvest the onion bulb, it may just be small. Sometimes due to changes in temperature, an onion plant will flower prematurely. This can happen just as a fluke too so it's best to plant multiple onion sprouts for better odds of scoring a full-grown onion!
- Frost may cause the green top of your onion plant to die off, so your bulb will need to be harvested shortly after that
How to Store Harvested Onions
Onions are ready to eat as soon as you pull them out of the ground. If you want to store them for later, you'll want to cure them first.
- Curing is easy. After harvesting, let onions dry in a warm, dry place with good airflow until the outer skin and stems are completely dry. You can lay them on dry soil, hang them, or place them in a wire basket or mesh bag. Rotate them as needed so all sides dry evenly. Curing typically takes 2–6 weeks and helps prevent rot during storage.
- Do not rinse onions to clean them off. You want to keep the onions dry to avoid rot. Allow them to dry then you can brush away any dirt.
- Once cured store your onions in a cool, dry place. Cured onions, depending on the type and size, can be stored for as long as 10 months!
And if your onion begins to sprout before you get to use it... well, you now know what to do! Use that sprouted onion to grow more onions!
★ FAQs ★
Onion plants rely on insects to be pollinated. However, when you're re-growing an onion from another onion that has sprouted, that plant has already been pollinated. So you can regrow it indoors.
Onions require a substantial amount of sunlight to thrive. They need 12+ hours of direct sunlight. Onions to not grow well in shade or even in indirect light. So if growing onions indoors, you will most likely need to use a grow light to provide enough quality light to meet their needs.
This depends where you live. Generally, spring is when you will want to plant. You will want to make sure that the temperature does not drop below 28°F (-2°C). You can keep your onion sprouts indoors for up to 6 weeks before transplanting to the ground if needed.
Note: The ideal soil temperature for onions is 50°F (10˚C) and above.
Yes, you can regrow any color onion that has sprouted! White, yellow, or red.
★ Recipes You'll Love ★
Once you've grown new onions, try making some yummy food with them!
I have a ton of easy recipes to give you ideas for what to make with your garden-fresh onions.
Browse all my super easy recipes and Pin your favorites for later.
★ More to Grow ★
Did you know you can also regrow a sprouted potato?
Wendy Karen Campbell says
Thank you for the information. I have 1 question. You said they, the sprouted onions, may keep for 3 weeks before planting. Is that necessary or now that we have separated them, may we plant them now?
Angela G. says
Hi Wendy, you can plant them right away! No need to wait.
Jackie says
Thank you for your article. I'm so excited to see what happens, usually I work on my flower beds, first year for veggies!! Again thank you.
Angela G. says
You're welcome. Best of luck with your veggies!
Kim says
Thanks for the info. Now can I plant onions in potting soil in the house since I live in an apt.?
Angela G. says
The onions require full sun so growing indoors would be tricky without a grow light of some sort. Do you have a balcony or patio with 6+ hours of sun that you could use?
Conny says
Thank you! Now I can buy old, cheap onions instead of expensive planting sets.
Angela G. says
Yes!
W jennings says
Thank you for sharing this information. I found it very helpful and easy to follow your instructions. You did a wonderful job from beginning to the end of all the stages of the onion process.
Thank you
Angela G. says
Thanks! I’m so glad you found my tips helpful. Good luck planting your onions!
Amanda says
I've been watering my new onion growth for about 1.5 months or so. I can see the bulb growing which is exciting. However, both my plants have started to bolt. They are flowering but do not look large enough... what should I do?
How do i prevent this for next time?
Angela G. says
Hi Amanda, this is most likely due to temperature fluctuation. Sometimes even during a normal growing season, changes in temperature can trick the onion into thinking it's ready to seed prematurely. The best thing to prevent this is try to plant when the temperature is more warm and consistent. You can cover the plants lightly with a blanket to hold in warmth at night during the cooler months. That may help. Sadly, you'll want to pull this and start again with a new plant. You can still eat the onion even if it's not fully developed. Here's some more information about onion bolting that might be helpful to you: https://www.gardeningknowhow.com/edible/vegetables/onion/onion-bolting.htm
Ed says
Can't you just pinch the flower as soon as you see it developing, just like you can do with basil, etc. To keep them from bolting? Or would that not be sufficient enough for the bulb to continue its normal growth pattern?
Angela G. says
Hi Ed, Once an onion plant starts the bolting process, the bulb will cease to grow. So even if you pinch the flowers, the bolting process has already begun. You can go ahead and harvest your bulb and eat it.
Tim says
@Amanda, cut the tops back. When they are younger. About 3 to 4 inch
Ed says
And you can eat or cook with the greens that you cut off!
Yaz says
Great post, thank you.
Monique! says
Thank you so much for this! Can't wait for the bulb babies to grow 😋❤
Angela G. says
You’re so welcome! Good luck with your onion babies! 🙂
Melissa Hyatt says
Thank you so much for the information instead of throwing away onion now I might get three out of them. Your directions are so easy to follow.
Angela G. says
You’re welcome Melissa! Glad you found the info helpful. Good luck with your three onions!
Asiya says
I really hope my onions grow. I am an 11 year old girl who really loves plants and wants to own a farm with plants and animals one day. I am already starting to grow strawberries, cucumbers, carrots, and basil, (and some marigolds because my mom says they might keep the bugs away from my plants) and I hope that I can add to my garden!
Asiya says
Do the onions NEED to sit for around three weeks before you plant them?
Angela G. says
No, that’s the maximum amount of time once you cut away the outer layers.
Asiya says
@Angela G., okay, thank you!
Joe says
If it is just the cut off top ~1/2" of an onion that is sprouting, will it grow new roots? Found some sprouting in my compost bin. I just stuck one in dirt so I'll see.
Angela G. says
Hi Joe, Most likely you do not have enough of the plant for it to regrow. You need some portion of the roots. Might as well give it a try though, maybe there's something there you can't see. Keep up posted.
Just a random person says
@Angela G., will it be ok if I just cut the flower off?
Angela G. says
Once the onion plant flowers, you will want to harvest the onion right away. Once an onion plant flowers, it affects the quality of the bulb. So the flavor may be affected and the onion may not store as long. You can still harvest and use the onion, just use it right away for best results.
Charli says
Can a person start these inside, then transfer outside once the weather gets nicer? I have a handful of onions that have really long sprouts on them and I want to try this, but I’m not sure if they will last another month.
If I should wait, what’s the best way to store them until it’s warm enough to plant?
Angela G. says
Hi Charli, While I haven't tried it myself, I believe you could start these inside and move them outside if you plant in a well drained pot and place in a very sunny spot. This site has more information about how to clip and store onion sprouts to regrow them later: https://www.globalseednetwork.org/seed-tips-detail.php?id=22. Hope this helps! If you have time and want to experiment, maybe you could try both methods and report back to let us know how things turned out!
Charlotte Cannon says
You made this so simple and brought me so many memories. At 76 and no man around I have not gardened for 20 years. I am experimenting and enjoying every minute. Thank you!
Angela G. says
Hi Charlotte, so glad I could help!
Lynette C. says
This is really helpful. I am learning as I go creating my first garden here in Wyoming. Starting everything inside since our weather is not stable. Thank you for the tips. So looking forward to fresh veggies this year.
Angela G. says
Hi Lynette, good luck with your garden this year. Glad I could help!