what's the secret of big onions?

I've been doing a bit of checking on the difference between the early and late Valencianas.

The early ones are whoppers. My biggest so far this year is 1124 g, a stripling in comparison with the 1541 g record from last year. I don't do anything special - no pipes, drip systems, fancy composts, etc. I just grow them in the ground and water from a watering can. However, they won't last much more than a few months, even if you store them in good, dry conditions

The late ones are still a fair size. I grew these last year and most were around 400 to 500 g apiece. They lasted for absolutely ages, well into April and May if you store them right.

Shokky, I have to say thanks to you for raising this question. It turns out that last year I grew both early and late Valencianas, but didn't know the name of late ones (both lots bought as plants). This year I've grown early Valencianas and some other type for winter storage onion and they're nowhere near as good (bought as plants on a recommendation). I can see them rotting quite quickly, meaning I've got about 100 kg of onions to use up between now and Christmas or thereabouts! Thanks to you and your question, I won't be making the same mistake again.

I imagine they'll stand up to frost pretty well. I plant them out as young plants in late April, in theory after the frosts. But this year we had a few nights of frost in May and they survived OK.

When is your last frost in Swindon?