Onions from seed......... a challenge

Hi all, I haven't been on the site for a while so apologies for that, now down to business.

This growing season will be my second on the plot so I decided late last year that I would challenge myself by growing onions fom seed, got a fan heater for the greenhouse, rigged up a thermostat for control, got the seeds ''Golden Bear'', read loads of info and got of to an early start with my first sowing second week in Jan. Germination rate was about 80%, transplanted the seedlings just after the 'crook stage' and all was looking good until the last couple of days, the seedlings are beginning to get long and spindly and bending over with their own weight........ is this normal? could I trim the long leaf stem and still expect further leaves to develop?

Once transplanted, mine went into the unheated greenhouse.

I'm having a go at trying onions from seed - have sown some Ailsa Craig into modules and stuck them in a coldframe but on inspecting today only seem to have one germinated out of about 20. They were sown about 3-4 weeks ago and went straight into the frame which has been quite cool. Guessing maybe I should have kept them warmer until germination and then put them outside..

Have seen sets around but not been fussed with trying them, doesn't seem to have the same challenge

I brought mine inside for a couple of days till they germinated and then put them back into the greenhouse