Onions - is this normal?

Hi.

Had a look at my over-wintering onions today. Some appear to have been pushed up and have an air  gap around the bulb area.

I bent down and sqeezed one of these pushed up bulbs, only to find that there wasn't really any bulb there. It was just the outer casing of the original onion set suspended in mid air, around a fairly substantial looking stem - a bit like a young leek stem.

Is this normal? Will that stem eventually swell to become the onion?

Seems odd to me.

The bulb is the store for the plant to start growing when you plant it. You want everything to go into the plant - this means no bulb.
When it knows it is going to have to stop growing late in the summer it bulbs up - that's when you want the bulb - not now.

In about a month; around St Patrick's Day; after the first spuds are in - try fingering them.

What you do is to loosen the soil around the onions, using a stiff finger or a dibber, or half a clothes peg - anything small and hard.......and the onion then absorbs all the spring rains and starts to bulb out and isn't restricted by any capping of the soil that has happened over Winter.

You only have to loosen the top cap; not too deep as you will disturb the roots. 

I can't really see how this is necessary when plants can push there way through tarmac and onions are mostly above ground anyway, but if you have time on your hands, the only issue is what root damage you might be doing.

The bulb is the store for the plant to start growing when you plant it. You want everything to go into the plant - this means no bulb.
When it knows it is going to have to stop growing late in the summer it bulbs up - that's when you want the bulb - not now.

Curious.

I got my allotment in late April last year and it was in a bad state.  By the time I planted onion sets it was really late. As they grew, they kept looking like onions (although I didn't feel the bulbs at any point) and produced small but edible results.

So is it  that over-wintering onions behave differently to summer planted ones? In over-wintering ones the bulb dissapears for a while but in summer ones, the bulb remains and just gradually gets bigger? I don't think I've read that anywhere. Just curious.

Cheers and thanks for other comments too.