We ran of our storage onions
this year in May --- better than most years, but still leaving me with a
two-month drought. With most vegetables, I simply substitute or
do without if our crop isn't sufficient, but I can't quite imagine
cooking without onions. So we ended up buying a few bags at the
store (plus planting 20% more to feed us over the next year).
We learned the hard way that garlic just doesn't taste quite right until it's been cured,
but onions are ready to go in the soup pot as soon as they reach full
size. I haven't even harvested most of our onions out of the
garden yet, but I've been pulling the biggest ones for soup for the last
week or two. It seems like we can never freeze enough soup or
grow enough onions --- maybe those two problems are related....
Jessie --- We don't use our Egyptian onions for the same purpose as our storage onions. Generally, we just use the Egyptian onions for green tops, although we do harvest a few bottoms in the winter to use like leeks. They have a slightly different flavor (and take a lot more processing per unit volume), so I don't think it's worth trying to make Egyptian onions your main bulbing onion.
Potato onions have more potential in that department, and last year they provided perhaps 5% of our onion bulbs. However, last winter 80% of our potato onions perished in our unusually cold winter, suggesting that that harvest can't be relied on and meaning that we're saving all the ones that survived to plant this fall. So onions from seed are still our main source of onion bulbs.
Charity --- I'll be curious to hear how your experiment pans out!
Nihal --- I have no clue about the number since we keep notes only on area devoted to each crop. We planted 9 beds this year, which equates to about 160 square feet of onions.