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.

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.