An onion sprouted in my fridge, how do I plant it?

There's an onion that has been cut in half by my girlfriend, but wasn't placed in a sealed bag afterwards.





So it's hanging out with the potatoes in the fridge, and it's got a few sprouts, the longest being almost 3 inches!





Now, should I leave it and let it sprout some more?





And how can I plant it or raise it to grow my own onions?

An onion sprouted in my fridge, how do I plant it?
If it is sprouted you can just go ahead and plant it. It will not form an edible onion. It will go to seed. ther will be a purple flower and than seeds. You can use the seeds to start new onions. Depending on where you live that will probably be next year. Most people buy onion sets at the nursery and plant those. starting them from seed and transplanting is a bit of work and time.
Reply:First, get a pot. Second, get some dirt at the bottom,at least one inch. Third, put some water in the pot. Then put the onion in and cover it with dirt. Finally, put some more water in the pot and place it by the sun. Make sure the onion is not to deep or it wont grow good. Water it twice a day. Oh and once it has grown enough plant it outside. After some grow repeat with more and you will have your onions.