Black onions

I grew Sturon onions this year in my usual containers with fresh compost. While they all looked good on the outside after drying nearly all were black and unusable when cut open.
All comments appreciated.
Thanks,
dogsbody

 

@dogsbody
I grew Sturon this year in the ground as normal and got good results.
Were they black and mushy or black and dry. A picture could be of use.
Was the top growth healthy? Did you see any maggots when you cut them open?
Just wondering if it could be onion fly: see here for more info Onion fly not something I have had an issue with, but that could be geography.

 

They were black and dry and the tops were OK.No pics though. A friend has suggested that the fact that I laid them out on sacking on the garage floor may be a factor. Could this be ?

 

Not something I've ever come across, but I doubt it has anything to do with the way you dried them.
Unless, did you dig them up when they were in full growth, ie still lots of leaves and not at the end of the growing season.

 

Interesting, we grew Sturon this year and dried and stored them as normal , all looking ok but when peeling some of the larger ones found that there was something like a second brown skin but down half way though the rings but only for the top half , not like a totally complete inner skin.

Wonder if thats something like whats happened with @dogsboys but disease has got in as well so easily turning them black ?

 

I noticed that problem last year.
My thoughts are when a long dry spell stops growth and the onion starts to ripen off, then it turns wet and regrowth starts.
In this neck of the woods it was an awful summer this year, but strangely my onions are keeping well.

 

I think Pete is spot on. I have seen the same thing myself in some years with distinct wet and dry periods.