Yes, you can plant a sprouted onion!
So, you have an onion or two that you bought from the grocery store, that have now sprouted in the pantry. And you're wondering, "Can I plant these sprouted onions and regrow a new, fresh onion?"
In short, the answer is, YES! You can plant a sprouted onion and grow a new one. Actually, usually you can get three new onions from one sprouted onion!
But, you can't just plant a whole onion in the ground. You'll need to do a little bit of prep work first. Don't worry, it's not hard at all.
I'll show you how.
So, grab your sprouted onion and let's go!
★ Steps to Plant a Sprouted Onion ★
Here's how to regrow a sprouted onion in just 7 steps from preparing your sprouted onion to harvesting and storing your newly grown onions. Easy enough for a beginner gardener to pull off.
Step 1: Peel the sprouted onion.
Peel off the "meat" of the onion, layer by layer, down to the center.
If your onion has sprouted, chances are some of the outer layers will be soft and may be starting to rot if your onion has started sprouting. If not, you can still eat the outer layers of onion that are not rotten, so don't toss them!
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.
I don't use a special tool for this. I just peel the layers off with clean hands.
Step 2: Separate the sprouts.
Once you get to the center of your onion, you'll want to carefully separate the green sprouts into individual plants.
Peel away any final layers of onion skin to reveal the separate plants if you haven't already.
Usually each sprouted onion will contain three separate plants! Sometimes less, sometimes more. It's a fun little surprise to see how many you will get.
Step 3: Separate each onion plant.
Carefully cut apart each spout, at the root, with a serrated kitchen knife.
Ensure that each sprout has some roots attached.
Step 4: Plant your onion sprouts.
Your onion sprouts will survive for up to 3 weeks before you need to plant them. You do not need to store them in water or soak them before planting. Do store them in a cool dry place though to prevent them from rotting.
Where to Plant Your Onions
You will need to plant your onion sprouts in full sun.
Onions require a lot of light. 12 or more hours of direct sunlight is necessary. So find a sunny spot in your yard, with loose soil, and plant your seedling spouts.
How Deep to Bury Your Onion Plants
Onion plants don't need to be buried very deep. You should plant the seedlings just 1" into the ground and space them at least 4" apart so the bulbs have room to grow.
Note: Planted onion sprouts will take about 3 weeks to look perky.
Step 5: Care for your onion plants.
Continue to water and weed around your onion plants. Fertilize as needed.
Onion plants prefer to be watered in cycles rather than every day. So you can water them about once a week unless the soil and plants start to visibly look too dry. Avoid overwatering as this can rot your onion bulbs.
Fertilize if your soil is not very rich.
Onions grow best in fertilized, well-drained, somewhat acidic soil. You can use organic (manure, compost, etc.) or store-bought fertilizer to ensure your soil has the nutrients it needs to nourish your onion to its fullest potential. Read more about how to test your soil for acidity.
Note: 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'll want to harvest a plant that has begun the bolting process whether it has a flower or not.
You can still use 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!
Step 6: Harvest your onions.
How Long to Let Onions Grow Before Harvesting
Your onions 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.
If your onion does not flower then you can let it grow up until the first frost.*
How to Harvest your Onions
Harvest by pulling the onion out of the ground and then brushing them to remove dirt.
Do not wash your onions.
Do not rinse your 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.
Storing Harvested Onions
If you're ready to eat your onion, go ahead! They are ready to eat as soon as you pull them out of the ground. If you want to store them for later, read on.
Step 7: Cure your onions for storage.
This is important if you have a large harvest of onions that you won't use right away.
So, if you plan to store your onions for any length of time, then you'll want to cure them first. Curing is easy. It's essentially just drying out the onion and letting its skin become it's protective "container."
How to Cure Harvested Onions
You can "cure" your onion for long-term storage by letting them sit in a warm place (75-80˚F) to dry up. You can hang them or place them in a wire basket or mesh bag with good airflow so all sides dry evenly.
Trapped moisture may lead to rot so make sure all sides of the onion get exposure to air either by rotating the onion or hanging each onion individually. Some people lay them out in the garden and rotate them so all sides get a chance to dry out.
The green tops will dry up and the outside layer of skin will firm up. When the stems are completely dry, they are cured. Depending on the size and type of onion, it can take 2-6 weeks to completely cure the onion.
Storage After Curing
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... 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!