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We’ve all had it happen. That rogue onion that manages to hide at the back of the bin.
Once onions come out of cold storage and hit the supermarket shelves, it’s only a matter of time before they wake up and start trying to grow. The outside will become dry and papery, and the whole onion will shrink as it puts stored energy into trying to make one last go at life.
Once an onion has sprouted, there’s nothing wrong with eating it. Provided it’s not actually spoiling or molding, it’s still fine to cut up for dinner.
The problem is, there isn’t much usable onion inside at this point. Rather than trying to eat it, it’s better to invest in a good crop of future onions. If you can plant it, you’ll reap a reward 3 fold by the end of the season.
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Dividing a Sprouted Onion for Planting
Onions are usually grown from seed, and a sprouted onion needs to be divided to grow properly. After the first growing season, if that onion had stayed in the ground instead of being harvested, it would have divided into multiple onions all on its own.
Each individual onion would be a bit deformed, as it competed for space with the others. By separating them, each onion can grow into a full-sized bulb, and allow you to harvest far more than you planted.
Start by peeling back the outer paper of the onion. Once inside, you’ll see that the onion has already started to section itself off into multiple onion plants.
Once you’ve peeled everything off, you should have multiple distinct onion sprouts. I had two onions sprouting in the back of my bin, and each of them had three individual onion divisions inside.
It’s not necessarily always going to be three, which makes it a bit of a mystery hunt. Even if you only have 1 or 2 green stems coming out the top, there may be other smaller plants inside that haven’t popped yet.
How to Plant a Sprouted Onion
At this point, you have tiny onion plants. In cold regions with a short growing season like ours here in Vermont, it’s actually common for gardeners to order in small onion plants like this from warm growing regions like Texas. With that in mind, actually planting a sprouted onion isn’t that strange a concept.
Onion sets, for example, are just small onion plant starts that have been harvested and cured to suspend their growth until they’re replanted. Onions are pretty durable, and even after you’ve basically ripped them apart and removed half their layers, they’ll still likely grow without issue.
Once divided, sprouted onions can be planted directly into the garden or potted up indoors.
Onions can handle a light frost and are generally planted outdoors from seed about a month before the last spring frost.
Your plants, however, have been tucked away cozily indoors and cold spring weather will be quite a shock. If it’s early, try potting them up and gradually introducing them to the outdoors to harden them off. If it’s mid-winter in a cold area, they’ll need to be grown completely indoors in pots until you harvest.
Onions are pretty easy to grow, but they can’t handle weedy competition and they need ample water in well-drained soil.
The time to harvest your new, full-sized onions will depend on how big their initial bulbs were at planting, and the onion variety. Generally, onion plants give you a head start on the season as compared to planting a seed, and gardeners harvest onions from started onion plants about 65 to 80 days after planting.
Keep an eye on your plants, weed them regularly and water them every few days. Soon enough, you’ll have several onions to replace that sprouted onion from your pantry.
How does the divided onion know not to bolt?
The divided onion doesn’t have enough energy stored to bolt. If you plant the whole onion, it will bolt, but if you divide it the plant has to replenish it’s stores by making another onion. It basically resets the clock, and if left in the ground it would go to seed in year 2 (just like planting an onion set).
Great! Thank you!
I really appreciate your research and experience, as well as your skill in sharing it all with us. Many thanks!
You’re quite welcome!
Extremely inspired! Everything is extremely open and clear illumination of issues. It contains really certainties.
A sharp knife and clean cuts is always preferable.
Same as any other bulb.
A garden is a health hospital for the body and mind. What happens in a surgery when you use blunt dirty tools and take them from one area to another?
The way a person gardens tells a lot about their mind and level of conscious awareness.
Some people stomp around & never even think about what their feet are really doing,
I even know a man who swears he’s a professional yet plants everything with the root mass 1/2 out of the ground and wonders why his plants die and struggle to even live. Simply… the man is ungrounded in himself and absent minded in his connection to the physical. Half here.
I started by planting a sprouted onion; now I cut the ends off every onion I use, place them in water till little white roots appear, and plant them. What a crop I had going! Well, somebody beat me to the harvest; I believe it was Mr. Squirrel that dug up and presumably ate my onions and half my garlic. If I encounter a squirrel with bad breath, there’s gonna be a showdown!
Oh no. Ha Ha!
That is funny. We have gophers… not sure if my onions will make it. But it is worth a try.
I have a couple of onions that have started to sprout. The red onions are organic, the sweet onion is not. We had snow today, like you, but the next few weeks look good. I’m thinking of starting them indoors, hardening them off and then planting…when is the best time to plant? I’m a 6b according to the USDA. I’m thinking after I harden them off in pots I can plant them and they will be good to go. Thoughts?
They can actually tolerate light frosts and you can plant outside a month before the last frost date so you should be pretty close the that now. I would save myself a lot of work and plant them outside within the next week or so.
Thank all of you for this wonderful information!!! I stumbled across this article through the reference section of a Wiki-how article.
Since the pandemic began my husband does the majority of the grocery shopping as he’s trying to protect me. Awesome! You’ll find me in the garden. I grow, he cooks, I clean up. Well, I hadn’t been paying any attention to what he has been buying in awhile. Then tonight I accidentally dropped a can on the pantry floor and was shocked to discover ten sprouted onions of all varieties. I can’t wait to try and grow our own!
My question is, do different types of onions have different nutritional needs if grown in pots? Thank you!!!
It sounds like you and your husband have a great system going there. The onions should all do very well in the same soil regardless of the variety.
I found a sprouting sweet onion in the bag. I live in Central Florida. Can I plant it outside in the ground now and if so how long before I can harvest? Thank you.
I would think that you can still plant them out in your area. They can handle a light frost. Typically onions are harvested 65 to 80 days after planting. It will depend on how big each of your initial bulbs are when you plant them. The bigger they are when you plant them, the sooner they can be harvested.
So I found a sprouting purple onion at back of crisper. The sprouts are pretty good size 5-6 inches. Its end of July here in NC, region 8. Wondering if I put them in ground will they thrive or should I put them in a planter pots? Also how often and how much watering do they need. Help!
I think you can definitely plant them outside.
THANKS FOR THIS INFORMATION, I LIVE IN SOUTH CAROLINA, WHEN WOULD IT BE SAFE FOR ME TO PLANT MY SPROUTS OUTSIDE?
They can handle a light frost. But if they have been in the warm house, the cool spring temperatures can be quite a shock. You may want to try planting them in containers and allowing them to gradually harden off before planting outside.
I’m In Scotland and the weather can be sometimes warm/ sunny or super cold. ( mainly cold and wet though even just now in the spring it’s been 2/3 degrees Celsius but the sun has been shining)
Where am I best planting? Will they be okay outside?
( I will be using a pot)
Just found a sprouted onion and really want to try to plant it! Never planted anything before so im a complete newbie.
Also is there a best soil to use?
Thanks
If you are planting them in a pot, I would keep them indoors until they get established. Once you are ready to move them outdoors, you can place them outside for small periods of time and gradually increasing the time each day to harden them off. You can use any kind of potting soil to pot them up.
I don’t have enough room in my garden. Would I be able to grow them in a big pot outside in the sun? If so how big of a pot and how deep? Thank you!
You want your pot to be at least 10 inches deep and as wide as you can get it. The wider the pot, the more onions you can plant. You need about 3 to 4 inches in between each onion to allow them proper room to grow.
I am in Texas and the sun can get really hot. Should these be planted full sun or partial? Morning or event sun? Thank you!
You want to be sure that your onions receive 6 to 7 hours of sunlight.
Thank you-I planted one not knowing that I should separate the inside ones-seeing very soon my mistake-I’m really just growing the green sprouts….question: the green sprouts I have are large and numerous….can I not use them in cooking as well? Like for example use them the same way you might use chives? (chopped on something) because they certainly have an onion-y smell to them
Yes you can definitely do that.
Hi, this post has been so helpful, thanks! A question I have though is if I plant my sprouted onion bulbs into a pot (it’s February in Michigan) could I transplant them later to the garden in the Spring, or would they not do well being dug up once in a pot?
You should definitely be able to transplant them into the garden.
How deep do you plant the bulb? Do you plant it so just the green is showing or deeper than that? If I have multiple onion pieces to plant, how far apart should I plant them?
You plant them so the bulb is underground but the green is sticking up. I’d put them about 6 inches apart.
Trying for the 1st time in pots. I have 2 sprouting onions s that I’m going to separate and see how many are inside. Super excited to give this a shot! Thanks for all the info!
That’s great. So glad you enjoyed the article.
I am eager to try this. I have a couple that have sprouted and look ready to produce. About planting the roots that some have mentioned. I recently started cutting the root end out of the onion when prepping to cook. The reason is that I don’t like to have the root end in my dishes. I noticed that if I don’t cut it completely, a little sprout (if there is a sprout which I suspect has something to do with the time of year) usually comes out with the root. I have two sitting in a shallow water until I can get them planted. It’s an experiment. Can’t wait to see how both methods work. Hoping they grow well cause my family loves onion in everything.
I love that you are experimenting with them. Let us know how it turns out.