Onions doing my head in!!

[Puddleduck]

I can't grow onions. I really don't know what I'm doing wrong but every year they go belly up. So this year I spent ages preparing the plot, loads of lovely manure, if I was an onion I'd have been really happy. Planted my little sets, and they started to shoot. The tops grew beautifully, nice strong green shoots, but a few weeks ago they keeled over and went yellow so I figured they were getting ready to be pulled. Today I pulled them and apart from three (out of a possible two dozen) they hadn't grown. At all. Still the same size as the sets and not even worth pickling. So I have a completely wasted plot that could have been used for something edible. I'm planning on digging the whole site over with some lovely compost and letting winter do it's thing before planting again next year but I could really use some advice on the best way to grow onions. Is it better to use sets or start from seeds? Do they even like manured land? Are there any plants thay they like to be near?

Same goes for leeks, they keep dying on me too.

[little blue duck]

how soon did you plant after manuring?
Onions, leeks etc can't cope with nitrogen rich soil, so you should wait several months after adding manure.
Is the soil well drained?
It should be for onions.

I prefer sets, as they seem to survive my tough gardening better than seeds!
Companion plant with carrots, the smells apparently confuse both the carrot fly & onion pests. and again, carrots prefer less fertile soil as it can make them fork.

[Carltonian Man]

Hate to say but it sounds very much like a mild kiss of onion white rot. Loads of it round here of late, mine did exactly the same as yours.