★ 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?
Angie says
Thank you. I have wanted to know how to grow spotted onions for a long time. Everyone told me to put the root end in water but, all I ever got was rotten onion roots. Next time I will know what to do.
Angela G. says
You’re welcome, Angie. Good luck!
Carlos Mirabal says
Excellent information. While simple, it makes a world of difference. I had no idea. Thanks
Anne-LaVonne Morgan says
@Carlos Mirabal, thanks all for this great info!! I googled and got a Farmer’s Almanac!! My sprouting onions thank you for their new life!!
Cheryl Parkhouse says
Mine currently look like this and are around a meter tall. Are they supposed to do this?
Paula says
What soil type should I use to plant the sprouts?
Angela G. says
Onions grow best in fertilized, well-drained, somewhat acidic soil and they like full sun.
Bobby says
Out of interest, when I peel away the onion is it a good idea to leave the 'flesh' and outer layer on top of the planted onions? I'm thinking it will breakdown and enrich the soil.
Angela G. says
I would suggest instead of leaving the extra fleshy part on top of the onion sprouts, that you add the flesh to a compost pile and give it a year to decompose before you add it to the soil.
Evelyn says
Hi!.... thank you for this info!....I planted the whole onion!....may I ask can I eat the green onion leave, like a spring onion?... thank you!
Angela G. says
Hi Evelyn, You're welcome! Yes, you can eat the green much like a green onion. The flavor is a bit more mild than a green onion would be but it is indeed edible.
Jennifer says
Oh my, I planted the entire thing and it's growing. Do I need to pull and replant?
Angela G. says
Hi Jennifer, yep! You will want to pull it up and separate the sprouts so they each have room to expand and grow into a new onion bulb. The good news is, you’ll have 3 new onions instead of just one nee one. Good luck!
Michael says
@Angela G., I've also done the same thing just last week - planted the entire onion once I noticed some healthy looking sprouts growing.
So it's not too late to pull it up and separate the sprouts? Am still pleased to know I can get more onions out of this one.
Thanks so much for your advice!
Angela G. says
Hi Michael! No, it shouldn't be too late as long as the sprouts are still healthy looking. Just pull the onion out of the ground and follow the steps to separate it into several sprouts. Good luck! Keep me posted if you can. 🙂
Michael says
Hi @Angela G.,
Thanks for confirming that and appreciate the tips. I dug it out just this evening and carefully peeled it down to the actual sprouts (there were two of them). The roots were already rather long so I made sure that I gently separated the two plants, but had to use a knife to evenly split the base where the roots met.
So now they're replanted, with fertiliser, watered and close to one another. The leaves are still a lively green colour so fingers crossed they stay healthy for the next three months. They should be ready for harvest by summer (here in Western Australia). 🙂
Angela G. says
Sounds like you’re on the rifht track now. Just make sure they aren’t too close together so they each have room to grow into a full sized onion without touch each other.
Ccbizz says
This was very helpful. Thank you! Do you want happen to know if garlic and scallions grow similarly?
Angela G. says
Glad you found this helpful!
Green onions you can regrow as well as long as you have some of the white part of the bulb along with the roots. Put this piece root-down in a shallow cup of water and wait for the greens to sprout then plant in dirt.
Sprouted garlic can be planted also. You will need to separate each sprouted clove and plant them individually similar to how you have to separate the onion sprouts.
Good luck!
Liz says
Thank you! Your tutorial is super helpful
Stephanie says
Glad my search led me here! Looking forward to seeing how it goes in a suburb of NYC with a purple onion! Thank you.
Angela G. says
You’re welcome, Susan. Good luck!
Susan says
Thanks, I was just going to stick the whole thing in the ground!
Angela G. says
You’re welcome, Susan! Good luck with your onions. 🙂
Liz says
@Susan,
Lol! I was going to do the same thing until I read the tutorial.
Marianne says
As the greens grow tall ca I harvest them like bunched green onions like I buy?
Angela G. says
You can but if you harvest the greens before the onion is done growing, that will affect the growth of the onion itself. You can wait until the onion is fully grown then use the green tops just as you would a green onion. The flavor is going to be more mild and skin will be a bit more tough though. If you want to sacrifice the onion itself, the newer greens will taste better. So my opinion is you have to sort of choose whether you want to grow these as green onions or a regular onion for best results but they are completely edible. Either way, this isn't a true green onion so you won't get the same green onion flavor you might expect. Hope this helps!
Margaret Carolyn Taylor says
Thanks so much, we came back after a 5 week trip and I had an onion sprouting in my pantry. It will be planted in my new raised bed garden.
Angela G. says
Perfect! Now it won't go to waste and you'll have 3 onions instead of just one! Good luck. 🙂
Cindy says
What is the difference between store bought and winter onions or do you know how to start winter onions
Angela G. says
Sorry, I'm not familiar with winter onions. I did find this article which may help you: https://www.gardeningknowhow.com/edible/vegetables/onion/growing-winter-onions.htm
Debra says
First time I got an onion that sprouted so I googled how to grow onions and came upon your site I did exactly as you said and I have three onion sprouts. I believe that they're going to do okay as this is the second week and the sprouts have literally grown. And I think you said it takes 3 months. They're not in very big pots two of them are together maybe two inches apart should I transplant those into something bigger??
Angela G. says
Sounds like you're off to a great start! Yes, I would put them in a bigger pot so they have room to expand and grow into a full-size onion. Ideally you want them to be spaced at least 4" apart. Good luck!