How To Plant A Sprouted Onion


Onions sprouting at the back of the vegetable rack are a common sight for the average householder. Indeed it is something that most folks have experience in their lives – even if it is just remembering their parents throwing them in the bin!

The fact is that once the temperature reaches over 68F (20C) then the onion will start sprouting. For this reason onions should be stored in a cool dry space at between 32-40 F if you want then to keep for any length of time.

onions sprouting in box getting ready for planting
Onions will quickly start to sprout in the larder when the temperature rises above 68F

However given that most of us keep onions in a vegetable rack in the kitchen (a bad move really) where the temperature is well above the ideal for long storage, sprouting onions become a fact of life if we do not eat them fast enough!

sprouting onions with outer skin  peeled away sitting on a chopping board in my kitchen
Peeling of the sprouting onion continues until the individual onion bulbs are exposed

So the good news is YES you can plant shot onions! instead of throwing them away. Here is how you can re-use this valuable food source simply and without great fuss.

How to plant onions that have sprouted

To regrow or plant a shot onion bulb, you simply peel away all the outer coats until you have exposed the bulbs formed under the skins. This is usually 2 or 3 bulbs. Separate them carefully at the roots, leaving some roots on each bulb. Place in a jar of water until more roots form, then plant as normal in the garden or pots.

skin peeled from onion to reveal seperate onion sprouts for planting
This onion has had all the layers peeled away to expose 2 bulbs that can then carefully be separated into onion sets. Be sure to leave roots at the bottom of each bulb

That’s all there is to it, and over the next few weeks the bulbs will form into healthy eatable onions once more.

Why you should be re-growing sprouted onions

onion bulbs seperated and exposed for placing into water
The onion sets have been carefully separated making sure that a decent root base is still attached. From here they will be placed in water for 7 days or so to encourage root growth before planting.

Ok so well all know that onions are fairly cheap to buy in the store, so are they really worth the effort of regrowing? Shouldn’t we just throw them away? Here’s a few good reasons why it is indeed worth the effort.

  • Why Not? If like me you are averse to throwing out potential food and abhor waste, then this is an excellent way to avoid needless waste and feed the family at the same time.
  • Family Time: This is a great little project to involve the kids in. Imagine sitting around the table with the kids and showing them a practical skill that they can do for themselves. This is true teaching at its best – and you do not have to have a university degree to do it! The project continues when adding the resulting onion sets to water and watching the roots form over a number of days – then planting the onions – invaluable life experience!
  • Its Practical: Ok so maybe onions are cheap to buy, but what if you do not live near a store where you can just buy them. As any off-gridder will tell you – It is much more practical just to grow your own and have food ‘on tap’ whenever you need it.  
Video presentation showing how to prepare onions for re-planting in the garden or planters

When to plant onions that have sprouted

Onions are a cold weather vegetable so they are usually planted in the early Spring or when the ground temp is around 70F (21C). They can stand a gentle frost so do not worry about that.

Onions also prefer free-draining, fertile soil conditions in a sunny spot where they should be planted in rows 6 inches apart with the rows being about 12 inches apart.

This distancing is mainly to allow for weeding between the rows over the growing period – if you are using traditional growing methods.

If however you are using Raised Beds or following the Square Foot Garden methods, then this distancing is pretty much done away with, allowing many more onions to be grown in the limited space that these methods provide. Clicking on these hyperlinks will take you to more articles about these exciting methods for growing veggies in limited spaces.

Does it matter what kind of onions?

Any onions including garlic or shallots can be re-grown in this way, as they all have a tendency to sprout if the conditions are right for them. The main thing is to let them sprout until you have clear shoots that you can separate into individual bulbs to plant.

Will sprouted onions grow into ‘full grown’ onions?

Not exactly! The re-grown onions tend to be more oval shaped – a bit like shallots but a little larger if they have grow as expected.

They are an excellent addition to stews and casserole dishes.

When to harvest the onions:

Planting sprouted onions is almost the same as planting onion sets except that they have a ‘head start’ as they are already in the growing stage.

In general terms, onions take around 90 days to reach maturity. Re-grown onions should take a little less time than that – just keep a watchful eye on them near the time for normal harvest.

Storing re-grown onions is exactly the same as for any onions you are storing – If you are fortunate enough to have a root cellar then the ideal temperature would be around 32-40F with the ambient humidity at 65-70%

James

Best Selling author of several no-dig gardening books, James has over 40 years of gardening knowledge and experience to share with like-minded gardening enthusiasts.

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