[Yana]

I've started the onion sets (red and yellow onions) off in modules and they are in an unheated room. I can see top growth on most of them and now worried that they will  out-grow the modules before I can get them into the ground. If I put them into an unheated greenhouse will that slow them down a bit? It's going to get cold over the next few days so can cover them with fleece if necessary.
What should I do?? 

[DD.]

I think you were a bit quick off the mark starting them off.

Even in the colder climes of Leicestershire, I just stick them in the ground from March onwards. They have plenty of growing time.

Onions do not need mollycoddling and it's really going to be too warm indoors. I'd move them to the greenhouse ASAP, they'll stand what our climate can throw at them, but you may already have weak plants that will be prone to bolting.

[Yana]

I think you were a bit quick off the mark starting them off.

Even in the colder climes of Leicestershire, I just stick them in the ground from March onwards. They have plenty of growing time.

Onions do not need mollycoddling and it's really going to be too warm indoors. I'd move them to the greenhouse ASAP, they'll stand what our climate can throw at them, but you may already have weak plants that will be prone to bolting.

I could see roots so thought it best to start them off. Serves me right for buying from a well known cheap high street store.
Have I completely wasted my time and should start again?

[DD.]

I'm not going to say that you've wasted your time, but I know what I'd do! 

[Yana]

I'm not going to say that you've wasted your time, but I know what I'd do! 

Start again I guess

[Mark's Sussex Allotment]

The onions will still have some use though.......

[DD.]

Depends on your available space. If you only have room for one decent crop, I'd be looking at getting some healthy sets.

[Goosegirl]

Depends on your available space. If you only have room for one decent crop, I'd be looking at getting some healthy sets.

If the top growth has only just started to show, you may be ok but get them in the gh as DD said pronto.

[Yana]

Depends on your available space. If you only have room for one decent crop, I'd be looking at getting some healthy sets.

If the top growth has only just started to show, you may be ok but get them in the gh as DD said pronto.

They've gone in the unheated greenhouse today.

[Totty]

If you want to keep them, you can put the modules on top of trays of compost, they won't get root bound in the modules then, you will break a few roots getting them out but I've found onion and leek plants quite resilient to this.
To be honest though, I would get some more decent sets and stick them in modules in about a month if that's how you want to do it, or as dd said just stick them in the ground mid march. Sets are known for being prone to bolting, and going from the warmth of the house, where they will grow too fast and spindly, to a cold greenhouse will lead to some sort of shock which will cause lots of them to bolt later on in the season.
Better off starting sets off outside from the get go really. (Or grow from seed )


Totty

[Yana]

Seems a good investment of £1 if I can get some more as I've not got loads of space to waste. That will teach me to look properly when buying sets and not to be too quick to put them in modules.