An onion thrown in the trash ended up sprouting a whole plant, but how is that even possible?

We've all seen a veggie grow a rogue limb here and there, but not usually to this extent.

A Reddit user took to the platform to share the insane growth of an onion thrown in their bin.

"The onion I tossed in my trash can before I went away on vacation is somehow thriving," they wrote alongside an image of bright green sprouts shooting out the top.

While most commenters were hung up on the fact this person left for a holiday without taking their rubbish out (it is kind of gross, to be fair), there were a few curious as to how on earth an onion grew in the trash.

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Thankfully, 9honey Science (not actually a real thing, by the way) is here to debunk the curious phenomena.

Now, this is going to be easiest to understand if you have an onion in your hand, so we'll give you a minute to go find one.

Got it? Good. If not, just picture one in your head – you'll be fine.

So you know the hairy top of the onion that we usually chop off? Well, those are actually the onion roots.

But unlike most plants that grow solely from the roots planted in soil, onions also have a bulb (the part we eat), similar to lilies and tulips.

When you buy an onion at the supermarket, the stem is cut off as close to the bulb as possible. But sometimes at a farmers market, you'll see onion with the stems still attached.

This is because, basically, when you cut an onion's stem off, it kinda makes them sad. See, onions want to have a stem, and they'll often used the energy stored in the bulb to produce another stem after the original has been cut off, even if there is no water or soil to fuel the growth.

Now, eventually the bulb does run out of stored energy, but it'll do its best to grow as much stem as possible especially if left in the sunlight.

That's exactly what happened to this person's rubbish bin onion.

But a sprouted stem grown in your kitchen is not the same as one grown in the ground.

When in the ground, the onion is taking nutrients from the soil to help it grow, whereas a stem grown in your kitchen is using the stored sugars and nutrients inside the bulb.

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And if you're wondering if a sprouted onion is still safe to eat, the answer is yes (maybe not the one from the trash though).

The only thing is, it might be a little less sweet and a little more bitter, since the bulb has used a lot of its nutrients and sugars to grow the stem.

The bigger the stem is, the less tasty your onion is going to be.

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