I harvest them when the tops start to turn yellow and fall over or if they start bolting and going to seed I pull them then. I lay them in the garage on the floor to dry out. I know some lay them outside to dry but between critters and sun that will scald them at that time of year. The garage is a much safer bet. I don't layer them in the garage. I lay them single file on the floor on cardboard or brown paper grocery bags to dry out. There they stay for several weeks and I have even left them there for longer. Then once they are dried out I cut off the dried tops and put them in a large cardboard box loosely inside in my pantry closet. Don't put them 2 foot deep in a box LOL. Just maybe three or four onions deep loosely in a box. My pantry closet is a cool dark space. They last quite a few months in there before they start to sprout.
These are the only photos I have of my onions drying. these were from a couple years ago. Yes the tops are a bit green on these but they were bolting and going to seed so had to pull them. They dried out fine. Our garage is insulated and I think that helps. Its cooler in there than outside and the concrete floor is cooler so I think that is good. I would love to hang them up to dry somewhere but I don't have a place to do that. Not that is safe from critters! I also dry out my garlic in the garage for the same reasons.
I was just telling honeyman last night... I am going to check the internet for canning recipes. There must be a canning recipe for canning jars of onions. I could use those in cooking easily. If there is a way to can them which surely there must be...then I will can some this year as well, for putting into soups and such. I would like to chop them up and can them just onions if that is possible. I don't want to pickle them as that wouldn't work for cooking with in soups and such. I would like to raw pack them then pressure can them? Anyone ever do this? If so would love to hear about it!
I looked in my canning books that I use most. They are older so you all do what you want on this. I am just passing on what is in them, its apparently not recommended now, so there is my disclaimer LOL.
So these are Kerr Canning books dated from 1943 to 1972 they say Peel, wash, boil 5 minutes. Pack in
quarts and pints, shows 40 minutes time at 10 lbs pressure. They even show hot water bath time but I will go with pressure canning. It does not say to cover with liquid. Pack within 1" of jar top it says. LOL well one book says within 1/2" of jar top and the other says 1" of jar top.
I would still like to hear about how anyone else cans onions :O).