Wanted to try something different this year, so I bought some onion bulbs in October from local garden center (Mayo's). I have no idea what type I bought (brown paper bag said YELLOW and they're about the size of large marbles with no green shoots)

Last spring I bought and planted the onion seedling sets (looked like small scallions), but didnt have great success (most grew nicely but didn't produce big, fat bulbs) even though I planted them in a raised bed with deep, soft soil (our carrots did great in this bed) We gave the onions sufficient room.

I'm not looking to break records, but it'd be nice to get some that were larger than golf balls (in fact, we really didn't even have golf ball sized onions...just scallions)

How do I grow nice sized onions?