Onions . . .

Successful cold storage-Onions
http://www.backwoodshome.com/articles2/gist82.html

By Sylvia Gist

(SNIP) ...  Ideally, I would have a root cellar which maintained the correct temperature for the produce I would like to keep. Unfortunately, it's not that ideal, so I have to look for other places to store things.

(SNIP) ... Onions

Perhaps my favorite vegetable in storage is the onion. The sweet ones have to be eaten in the summer and early fall, but the pungent ones can last until you have the next crop. A couple of long-day hybrids, Copra and Norstar, have worked well for me. I start the seed indoors in February, feed them fish fertilizer, and set tiny plants out in early May. Norstar matures sooner than Copra, but both are narrow necked hard onions of medium size. In August, I quit watering them.

When they mature ...   ---CONTINUED---

How to Harvest, Cure and Store Onions – Root Cellaring, Braiding, Dehydrating and Freezing
https://commonsensehome.com/how-to-store-onions/

You can enjoy home grown onions for months after the growing season has finished with just a little extra time and effort. In this post we'll cover onion harvest, curing onions, and several different onion storage methods. ---CONTINUED---

Drying you onions properly for storage is a must so they don't get mushy and affect the other onions, as they will rot. From the gardeningcannel.com:

https://www.gardeningchannel.com/how-to-dry-onions-for-storage/