By Tonyanderson
United Kingdom 
why do onions thicken just above the bulb
On plant
onions
4 Jul, 2012
Answers
I think he may mean a condition called 'bullneck.' This occurs with planting in soil that is too rich in manure, or maybe planting too deep. The onions affected can be used, but will not store for long.
5 Jul, 2012
thanks for the replys and noted about manurering
5 Jul, 2012
Do you mean the stem where the leaves grow, if so that is how the onions grow.
4 Jul, 2012