Mould on onion sets

Hello,

anyone know why my onion sets that i need a couple of weeks or so ago are getting a mould on them? They rooted really well but noticed this mould.

is the heated greenhouse to mild for them? Should I stick them in the shed instead?

 

Hopefully it's only attacking the brown outside skins.
I'd think increased ventilation might have an effect on it.
Try to keep the surface of the compost dry.

 

Hi Snorky85, I sincerely hope it's not onion white rot? If it is? discard the onions and soil, thoroughly disinfect EVERYTHING associated and beware that it can remain in soil for 7 years plus. I have it here in London!