[mikem]

For a few years some of my onion sets when harvested have a second, brown skin, part way through.  It seems from searches that this may be due to my onions going through a cold spell or reduced light (sun?) and then start growing again.  I start my onion sets off in modules in order to get a good start when the soil/weather may be a bit cold and to stop the birds pulling them out.  Do you think that this may be the reason for the brown "second" skin or could it perhaps contribute to the problem i.e. should I just plant later straight into the allotment in future?

[Fairy Plotmother]

I planted my sets directly in the bed and most of them have brown skins on the inside.! I just remove that layer.

[Yorkie]

I've grown them from modules and not had this second skin, so I think it's unrelated to that!