I harvested almost all of our onions about a month ago , some were real nice four inch'ers
As we only had a three or four stone of them I was able to lay them out on 1/2 " chicken wire frames , under cover but still able to get some sunshine & plenty of air movement on them.
Like most of you , a lot of the Red Barron onions won't keep very long but those that will are good solid specimens ..we'll be eating these first
One thing that comes to mind and it is done by the commercial onion growers in East Anglia ( I used to live there ) is that before the actual lifting ..about 14 days before the rows are loosened to leave the roots still below the ground .
I reserched this practice and found it's to fool the onion to stop nutrient take up at the previous rates it had been doing . This evidently helps close the onion down Allows the tops to fall due to less moisture being drawn in by the loosened roots and thus helps with the long term storage .
Long term storage .
Can be done in " Plastic bread trays " or seed potato trays as in the old days in a frost free place with free moving dryish air situation .
or
If you get the lifted onions with uncut tops ripened up to a yellowing golden brown , plait them up in 10 pound or so long strings and hang them up away from the walls .
Remember to trim the roots & soil off to help keep pests off the onions however you store them .