[AlaninCarlisle]

I followed others and sowed seed in January. For the hell of it, I grew some monster onions by planting out, not in open ground but in rich beds in the polytunnel. Some of these ended up as big as any I've ever seen in competitions. However, they all had one failing - their keeping qualities were rubbish and I've just had to discard at least half of them as they were rotting. The more normal sized ones are fine.

Is this typical of monster onions?

[mumofstig]

Some of the big varieties like Ailsa Craig are just

Not recommended for long storage.

http://www.suttons.co.uk/Gardening/Vegetable+Seeds/All+Vegetable+Seeds/Onion+Seeds+-+Ailsa+Craig_172866.htm

[jambop]

My experience with onions tells me that the variety is a hugely important factor when it comes to keeping qualities . However I also think that onions grown in very fertile soil which has had manure added to it will result in large onions which tend to rot and in general the smaller onion it more likely to be a good keeper. Search the seed catalogues for the best keeping onions and use those. Interestingly I have found that yellow onions tend to store better than reds or white.