How to Regrow Sprouted Onion Bulbs
Cooking onions are prone to sprouting quickly, which begs the question, can I regrow sprouted onion bulbs? And, are they safe to eat? Find out how to regrow sprouted onion bulbs, and how to prevent them from sprouting in the future. You can also grow your own ginger plant indoors using a root from the grocery store.
About The Humble Onion
The onion (Allium cepa), also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus Allium. The shallot is a botanical variety of the onion. Until 2010, the shallot was classified as a separate species.
Whole onions and shallots are best stored in a cool, dry, dark and well-ventilated room. Ideal places include the pantry, cellar, basement or garage. Peeled onions can be stored in the fridge for 10–14 days, while sliced or cut onions can be refrigerated for 7–10 days.
By nature, onions are biennial plants. Their natural rhythm is to grow from a seed, to a plant, and then into a dormant bulb in their first year. The following spring (after being exposed to cold but sub lethal winter temperatures), the bulb will begin growing again and soon produce a flower spike.
Sprouted Onions Are Safe To Eat
It’s very common for onion bulbs to start sprouting (growing green tops) after coming home from the grocery store, despite our best food storage methods. These are the onions with the papery skins that we use in both raw and cooked form. They need cool, dark and dry storage; it’s the warmth and/or light in the kitchen that gets them sprouting. They will also sprout faster if stored near potatoes.
This Sprouting Does Not Make the Onion Unsafe To Eat
In short, sprouted onions are perfectly safe to eat. The catch is, you may not like their taste.
You Can Continue Growing Them to Harvest More Onions
Yep, you can regrow them easily. I’ve detailed the instructions below.
How To Regrow Sprouted Onions
Have a look at the image to the left. It’s a cooking onion that has begun sprouting. To regrow it, you will be removing the sprouts right down to and including the roots, and setting the rest of the onion aside (you can use it for cooking if it’s still fresh).
1. Prepare Pot
Get a pot with drainage holes ready. Fill with potting mix made for organic vegetable growing.
2. Cut Onion Around Shoots
Using a clean knife carefully cut the onion in two (but not down the middle or you will cut through the part we want to keep whole).
3. Reveal Shoots
Carefully cut onion open, revealing green shoot (or shoots) inside. Each one will form a new plant.
4. Peel Outer Layers
Peel away the outer onion layers, keeping the entire shoot(s) attached to the base (roots). They cannot grow without their roots.
5. Plant Onion
Plant each onion shoot 2 inches apart or more, burying roots one inch into potting mix.
6. Water
Water until damp, but not soaking wet.
7. Choose Sunny Location
Choose a sunny location, and do not let the soil dry out.
8. Harvest When Tops Dry Out
Onions are ready to harvest when the tops (greens) turn brown, wilt, and dry out.
How To Regrow Cut Onions
The easiest way to regrow onions is to set the bottom half (roots side down and cut side up) in a shallow dish filled with no more than ¼ inch of water on the countertop. Replace the water daily. After a few days, you should see the innermost core of the bulb begin to grow higher than the outer layers. Once the stem has grown a few inches, the onion is ready to be planted in soil either indoors or outdoors. Or, you can continue growing the onion in water, but you must continue to change the water daily.
Frequently Asked Questions
1. The Onions In My Kitchen Cupboard Have Sprouted. Are They Safe To Eat?
Yes, but…keep reading.
2. Do Sprouted Onions Taste Different Than Non-Sprouted Ones?
Yes. When onion bulbs begin sprouting, the new growth gets some of its energy from the sugars within the bulb (see plant diagram). This means the edible parts have been depleted of some of that natural sweetness, and the texture is a bit tougher. Some people don’t mind these changes, others do.
For me, it depends how far along the new growth is. If it’s just a little sprouting, it means the onion will pretty much still taste the same because it hasn’t lost that much of its sugars yet. If the sprouts are a few inches long or longer, the onion bulb will be quite bland. The article “Using Sprouted Onions,” from Cook’s Illustrated describes their taste test:
Random Cool Fact: The edible parts of onions-those layers that we can peel away-are actually modified leaves, also known as bulb scales.
3. Are The Sprouts Growing From Onion Bulbs Edible?
Yep. Will you like their taste? Probably not. If you’re a hardcore onion fan, take a sample and decide for yourself. Will they harm you? Nope.
4. What’s The Best Way To Prepare The Sprouted Onion For Cooking?
The green sprout grows from the root of the onion, up through the bulb’s center, and out through the top. The best way to salvage the onion is to cut it open (half it carefully close to the center), pull out the entire green shoot with the roots, and use the rest. If you want to regrow the green shoot, see the instructions above before cutting into the bulb.
5. Are Sprouted Onions Toxic For Pets?
Cats, dogs, and some other animals do not do well with onions-sprouted or not-and can become ill from eating them. If you have a pet that randomly nibbles, store onions and onion plants away from their reach.
6. Can I Regrow Sprouted Onions?
Yes. In fact, because they are already sprouting (growing), is a confirmation that the plant is viable, making regrowing them even easier for you. Some grocery store foods are treated with growth retardants to prevent this from happening, but if yours is sprouting, then that means it’s good to go.
The secret to most vegetable regrowing is the presence of the stem growing a tip, for onions this is the base where the tiny “hairy” roots grow. You can grow or regrow your sprouted onion as a houseplant in a sunny spot, or plant it in your garden (in containers or the ground). Often there are several plants sprouting within each onion bulb.
7. Are Sprouted Garlic Bulbs Safe To Use?
Same story as the onions: they are safe for humans, but the taste is altered. If the sprouts have just started, cut them out and use the rest of the bulb for cooking. If you want to try regrowing garlic, you can use the same instructions above.
8. How Can I Prevent Onions And Garlic From Sprouting?
Light and warmth are the culprits of the sprouting. Store both in a cool, dark, dry place with temperatures between 55 to 65°F (13 to 18°C). This is often a lower temperature than we have in our kitchens. Moderate humidity will help prevent drying out. I do not recommend storing onions inside a refrigerator.
9. Can I Also Regrow Shallots?
Yes, as long as the bulb and roots are still intact. If you just have the lavender edible parts without the roots, then no.
10. Can I Also Regrow Scallions?
Yes, same as for shallots. If you just have the green edible parts without the roots, then no.
This article at Anktangle on growing sprouted onions has much better photos of each step.
Let me know if you grow your onions and how it turns out. It can be quite different growing them indoors versus outdoors. I find indoors is always much slower. If you like this stuff, sign up for the newsletter and you’ll get new sustainable, plastic–free and zero–waste living ideas delivered right to your inbox.
Sources:
Wikipedia
https://en.wikipedia.org/wiki/Onion
The Best Way to Store Onions – Healthline
https://www.healthline.com/nutrition/how-to-store-onions
May 17, 2018
Growing Onions: Sets or Seedlings? – GrowVeg.com
https://www.growveg.com/guides/growing-onions-sets-or-seedlings/
Mar 18, 2011
How to Regrow Sprouted Onion Bulbs
https://empressofdirt.net/regrow-sprouted-onions/
February 25, 2019 by Melissa J. Will