The secret to onion sowing success?

For the last few years I’ve been growing onions from seed. I prefer the full sowing and growing journey to restarting growth from onion sets. My seeds have always germinated well and I get a good cropping volume out of them but, if I’m really honest, I rarely had an onion that reached a properly decent size. Until last year. For the first time ever I produced a few rows of big, healthy onions that wouldn’t blush with embarrassment on the show bench. A few of them could even be described as whoppers.

It’s now time to sow this year’s onion seeds, which means trying to remember what I did differently last year. I always sow them in January on damp seed compost, cover with another fine layer of compost, and keep them somewhere warm to germinate (in a propagator for the past few years), growing them on indoors with maximum possible light. But last year, I think, the difference came when I potted them on. Rather than wait forever until they reached the suggested 15cm tall I hurried them into new soil much earlier. Onions are notorious for not liking competition from other plants (they get more regular weeding than any of my other veg) and I suspect in previous years they quickly ran out of nutrients while competing with their oniony neighbours in the sowing tray. Mostly they’re pretty robust plants, so as soon as they look vaguely strong enough they’ll be lifted and rehomed a long time before hardening off and planting out.

Of course, it could simply be that last year’s chosen variety, Bedfordshire Champion, was more suitable to my sowing methods than previous varieties. So this year I’ve sown some more Champions and another, Red Baron, to test this possibility out.

Seeds sown:
Bedfordshire Champion, Kings Seeds
Red Baron, Mr Fothergill’s