★ 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?
Angela says
Okay, so I found your article AFTER I had already planted my full onion. I did not peel any layers and the sprouts continued to grow. However, yesterday I noticed a flower. So, would I be able to harvest and start over? Or should I just trash them?
Angela G. says
Flowering typically means a garden plant is past the point of producing a quality harvest since the plant's energy is now focused on the flower/seeds and not on developing the fruit/vegetable. But you could try pulling it out and separating the individual sprouts then re-planting each one and see what happens. Prune off the flowers if there are any left before you re-plant. Good luck!
Andrew Kairis says
I left two plants together.... Is OK?
Angela G. says
I would pull them and separate the two plants. If the seed plants are stuck together, neither of them will have the correct amount of room to expand outward and grow into the ball shape of a typical onion.
KathyG says
I live in central MS and it’s already middle of May. Is too late to plant my sprouted onion?
Angela G. says
Nope! You should be good to go ahead and drop them in the ground and give them until fall to grow.
Maryanne says
Wow, so interesting. Will surely try this. I have 2 sprouted onions that I will experiment with. Thank you so much.
Angela G. says
You're welcome, Maryanne! Good luck with your onions!
Jimmy Bob Moon says
It's fantastic what we can learn when we read.
Kim says
Thankyou for this info. I waste way too many onions so im excited to watch them grow 🙂
Angela G. says
Good luck with your onions!
Angela G. says
I think you're safe to go ahead and pull it out of the ground as long as the spouted part is still green. Good luck!
Sharnika Thomas says
I planted the whole onion before I saw your story can I dig up and start over
Angela G. says
You're so welcome Silvia! Good luck!
Silvia says
Super! Very helpful! I'll plant my onions tomorrow!
Thanks so much!
CJJ says
HELLO THERE HOW MANY ONIONS CAN I PLANT IN A 8 INCH DEEP AND 12 INCH WIDE - I DID EXACTLY AS YOU SHOWED AND ITS READY TO PLANT IN A POT - I LIVE IN A CONDO AND IN CANADA CAN I LIVE MY POT OUT SIDE ?
THANK YOU SO MUCH
Angela G. says
You'll want to plant them 1" deep and space them at least 4" apart so they have room to grow to full size. Onion plants are hearty and can stay outside as long as the temperature is above 20˚F. Good luck!
Marylin says
@Angela G., Hi Angela, can I know what type of soil is needed? I am about to plant a sprouted yellow onion I found in my fridge . 😅
Angela G. says
Hi Marylin, Onions grow best in fertilized, well-drained soil. You can use organic (manure, compost, etc.) or store-bought fertilizer. Good luck!
Erica says
We are going to plant today but in PA (Early spring). Is it too cold to put out on patio? Or keep Inside till it's warmer?
Angela G. says
Hi Erica, Onions are supposed to be pretty hardly and do OK in colder temps. This gardening site says as long as it doesn't drop below 20˚you should be good and that late March or April would be a good time to start! Onions do take awhile to grow big so better to get them in early and just keep an eye on the crazy PA weather. 🙂 Good luck!
Ricky Allemond says
This is so cool and will definitely give it a try
Angela G. says
Nature is awesome! Good luck, Ricky!
Donna Petty says
Thank you for the tips. I am ready to give this a try...
Angela G. says
You're welcome! Happy gardening!
A Flinn says
Thanks. I'll give this a try.
Angela G. says
Happy to help! Good luck with your garden. 🙂