Onions. Where did I go wrong?

[bend1pa]

For the first time I planted out some sets of red onions last October. Most seemed to be growing OK with sturdy, long thin foliage produced from late spring into summer. Throughout the spring and early summer it barely rained, and I did not water. But from midsummer onwards there was plenty of rain.

Anyway I dug them up recently and it was disappointing. Many of the sets had disappeared. About half the sets that survived had barely grown bigger, and those that were larger were nowhere near full size. These bulbs still have plenty of root on them and are firm. In a few cases, new shoots are emerging. Should I replant them and try again?

[Snoop Puss]

What variety did you grow?

To be honest, I think it unlikely that you would have any success if you're hoping to get a usable onion bulb as they're biannual, meaning that next spring they'll bolt.

When you say new shoots are emerging (i.e. they're beginning to bolt), is that one per bulb or several? If several, you might have luck with growing a local red version of 'calçots', essential onion shoots that are barbequed and eaten with a tomato and ground almond or hazelnut sauce. Delicious and a great way to turn produce that many would be disappointed in into a proper treat that is really quite expensive when purchased in the shops.

[ameno]

You say you planted them in October, which means there are overwintering onions. Those are meant to be ready to harvest in late June or early July, so if you say that it was dry early on but rained more after midsummer then the answer sounds like they didn't get enough water during their actual growing period. By the time the rain came, it was already too late to make a difference.

[bend1pa]

What variety did you grow?

To be honest, I think it unlikely that you would have any success if you're hoping to get a usable onion bulb as they're biannual, meaning that next spring they'll bolt.

When you say new shoots are emerging (i.e. they're beginning to bolt), is that one per bulb or several? If several, you might have luck with growing a local red version of 'calçots', essential onion shoots that are barbequed and eaten with a tomato and ground almond or hazelnut sauce. Delicious and a great way to turn produce that many would be disappointed in into a proper treat that is really quite expensive when purchased in the shops.

Just the odd shoot per bulb. I thought all bulbs usually begin to show shoots around this time onwards.

You say you planted them in October, which means there are overwintering onions. Those are meant to be ready to harvest in late June or early July, so if you say that it was dry early on but rained more after midsummer then the answer sounds like they didn't get enough water during their actual growing period. By the time the rain came, it was already too late to make a difference.

I left them in the ground during June as the few I did dig up were far too small So I kept the rest in the ground.

Do onions need a lot of watering? With non-bulbous vegetables, wilting of foliage is the first sign that it's too dry, eg toms. With onions it's more difficult to tell. During the winter months there was a fair amount of rain. It was during the spring and early summer that it did not rain for a few weeks and I noticed the ground looked dry.

[ameno]

Just the odd shoot per bulb. I thought all bulbs usually begin to show shoots around this time onwards.

They do if you leave them in the ground, yeah. Onions are meant to be harvested and taken into dry storage as soon as the leaves die back. If they remain damp they will indeed start growing again, and as they do they will shrink.

I left them in the ground during June as the few I did dig up were far too small So I kept the rest in the ground.

Do onions need a lot of watering? With non-bulbous vegetables, wilting of foliage is the first sign that it's too dry, eg toms. With onions it's more difficult to tell. During the winter months there was a fair amount of rain. It was during the spring and early summer that it did not rain for a few weeks and I noticed the ground looked dry.

Generally speaking you shouldn't be using wilting as a sign of needing water, anyway. You should be watering things before it gets that bad.
Onions don't need lots of water, no, but they still need enough. If there is no rain, especially during the period when they are meant to be swelling at their fastest, they will not grow much. And onions are a very season-sensitive crop (they respond to day length), so this lost growth cannot be made up later.
Also, they don't grow over the winter, so it doesn't really matter how much rain they get then. Then just sit in the ground waiting for things to warm up.