I can't get vfems link to open right now for some reason and I am sure it says this in the information provided there. But the little onion sprouts that you have on the top: eventually if left be, will become too heavy for the stem to support and will fold down so that the onions are on the ground. They will then take root and multiply that way. You can of course do this yourself and plant them where you would like. They are very hardy.
I like to take the young tender shoots and use them in potato salad like you would a chive. My grandmother has had a patch of these growing in her yard for over 28 years!