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?
Jenna says
Thank you for this excellent guide! I'm very excited to plant my sprouted onion. I'm going to try growing it inside, as it's still a bit too chilly outside for our garden. Do you have any recommendations on what size pot I should plant each sprout in? I'm trying to figure out what will give it enough room to grow, but still fit under a grow light alongside some herb seedlings. 🙂 Thanks in advance!
Angela G. says
Onions grow just below the surface so you don’t need a pot that is too deep, just make sure it drains. You can fill the bottom with rocks then a layer of dirt and/or make sure there are holes for extra water to drain out.
As far as the size, I’d say a pot with a diameter and height of 8” or more would be ideal. Best of luck!
Jenna says
This is the clearest, best explanation ever. kudos and thank you.
I'm going to go and use the outside of my onion now and look inside for the slender sprouted stems.
Yay!
Angela G. says
You're welcome! Happy planting!
Jim says
@Angela G., yes easy to follow info. Thank you.
Sudharsan K says
Hi, I'm from india, I think humidity in my living place is around 40°c, is it possible to grow potatoes here?
Angela G. says
Hi, I am not sure but I would say, go ahead and give it a try!
Jerry says
@Sudharsan K, try growing sweet potatoes which love the heat. Regular potatoes don’t like it that hot.
Helel says
Thank you. Looking forward to an end result.
Angela G. says
Best of luck, Helel!
Aguye Hitler says
Ooops! I just planted some sprouted onions from my kitchen (directly into the ground without peeling to separate the sprouts). I will watch and see what happens comparing your method.
Angela G. says
The onions will still grow but they wont have the room they need to expand like they would if you separate them. Have fun and see what you get though if you want. I'm all for experimenting.
Kay Jei says
What can I do to keep a sprouted onion over the winter? Should I grow indoors with a light, or is there a way to keep it until planting in spring?
Angela G. says
Hi Kay, You could try growing indoors with a grow light or in a window. I don't have experience with this first hand, so I'm not sure how well it works. If you try it, let us know!
Stephen says
Do you still separate the onion sprouts if you want the greens?
Angela G. says
You don't have to. The reason you separate them is to give the bulbs room to grow in a round uniform shape. The sprouted onion will still grow if you don't separate it, the bulbs will just be bunched together. Shouldn't affect the green tops either way other than maybe they won't get even sunlight if they are too bunched.
Stephen says
@Angela G., thanks Angela!!
Rosetta says
Can one use same procedure to plant garlic?
Angela G. says
Hi Rosetta, Yes. Sprouted garlic can be planted and you can use this same method. Good luck!
Rosetta says
Love the detailed and step-by-step procedure. Will try it out and revert.
Therese Bizabishaka says
Thanks for the tutorial. My question is would this work for a red/purple/Spanish onion. I have one in my cupboard that has sprouted. The sprouts a quite long and pale. Will that matter. Also to clarify after peeling and seperating the sprouts do you need to let them sit or could you plant them straight away?
Angela G. says
Hi Therese, YES this process works for red onions as well. As long as the sprout is green, you should be OK. Onions are pretty hearty so even if it's a pale green, once you put it in some sun, it should thrive. You do not need to let them sit out, you can plant them right away.
Thatpassionatecook says
Hey Angela
Happy that I read your article, as I was going to plant the entire sprouted onion in my backyard 😁 I peeled the onion & I got 8 onion sprouts. I shall plant them tomorrow.
Thankyou for the tips 👍 I'll let you know how my onions turn out.
Angela G. says
Wow, 8 sprouts! You hit the jackpot. Good luck! Please do keep me posted. 🙂
Susan Holeman says
@Thatpassionatecook, You must live in the South, lucky you! But if you live in N/E Missouri, as I do, my sprouted onions will not wait for the spring when the ice and snow is gone.
Angela G. says
I haven't tried it yet, but you should be able to grow onions indoors as long as they get sun. I plan to try it this winter as I live in Pennsylvania and our onion growing season has come to an end. I'll keep you posted!
Dominic says
Thanks for the tips 🙏
Wanda says
Thanks for the tips I'll let you know how my onion turns out
Angela G. says
Wanda, can’t wait to see your onions!
Jody says
I'm confused. You said in your article that onions were self pollinators but in your comment section you said that they needed insects to pollinate?
Angela G. says
Hi Jody, Onions plants do require pollination when grown from seed. However, when you're regrowing an onion from an existing onion, the original plant has already been pollinated so it does not need to be pollinated again. Hope this helps clarify. Thanks for asking.
Daniel Pawa says
Thanksfor this vital infor. I just want to plant bulb onion
Angela G. says
You're welcome!
June Speirs says
I have just planted my shoots I had originally put the onion in water but then seen your post really looking forward to watching them grow ready for my winter soup 🍲😊
Angela G. says
Good luck and yes, I'm already looking forward to winter soups too!