I planted onions in May and pretty much left them alone except for watering. Problem, they grew out of the ground where the 'Onion' was pretty much exposed rather than growing underground. I did exactly what the package said when I planted them so not sure what I did wrong? We pulled them today and plan on having them marinate overnight in red vinegar with some cucumbers I picked.
Like a lot of folks, I used to think that Onions are a "root crop" ... but the onion bulb is actually an extension (or termination) of the leaf. The roots of the plant stick out of the bottom of the leaf "bulb".
I don't know if I described that in the best way ... but, I hope you get the idea.