I have problems with onions as well. They do well as small green onions, but never develop to the larger onion size. moderator's note: split this post into it's own topic
Do you know what variety you planted ? Were they sets or seedlings ? There are several varieties that only make the small scallions, some that are mid size that are usually sold with green parts attached but look like a large green onion. Then there are storage types,,these are the ones that make the large bulbs and can be cured and stored all winter !!
Assuming they are the type that does make larger bulbs, there's a couple things to remember about onions. They are HEAVY feeders. They need loose soil, not too much clay. Plant them where just the roots and tiny bulb are covered, not deep. SPACE them 5-6 inches apart, they have to move all that soil between to swell to larger size, where will it go if they're too close? If you want to pull some for scallions, or green onions, put those close in a separate row. Pull every-other-one to have scallion will stunt the ones you leave. Onions are shallow rooted and don't like to be disturbed. Don't cultivate deeply with a hoe, that will stunt them too by disturbing those shallow roots. Hope you have better luck this year. Steady water too.
