If it is a damp time, it is safer to move the onions under cover, where they can be hung up in an airy, dry place.
Onions can be stored in a cool shed or garage. The conditions necessary for onion storage are:
Store onions in:
Onions with thick, fleshy necks will not keep & should be eaten first and not stored.
If onions are not completely dry when they are put into storage there is a risk that they will develop neck rot. This is when a fungus starts to develop around the neck area and gradually rots the onion from the neck down. Onions must be checked for Neck Rot (latin name – Botrytis allii, B. squamosa and B. cinerea) regularly in storage, & removed, because the rotting onions will destroy other onion bulbs in storage.
White onion varieties are more susceptible to neck rot, but red and yellow varieties may suffer. Garlic, shallots, chives, and leeks are also affected by neck rot.