Beans/corn in heated propagated?

Is germination of beans and sweet corn better in a heated propagated. I have just lost all my young plants from an unheated greenhouse and am desperate to catch up 

I have always started off my sweet corn in electric propagators. No problems whatsoever, never, until this year when I decided for some strange reason I would chit and then sow into pots. That turned out to be not my best idea this year. What a pain with very poor results. So, I have now got another batch under heat today as normal, albeit 10 days later than I would prefer. It's not too late at all for sweet corn, although I prefer to get mine off to as early a start as possible to miss the local young badgers frolicking around come September. I can normally get a crop in and finished by the end of August, first week in September.
In a propagator they are always up and showing in 5 days or less. I fully expect them to be up by the weekend, when they will head to the greenhouse for about 10 days, then a short harden off and out before the end of May under a protective mesh for a few days to help the hardening process, and in particular to keep the wind off for a fortnight.
 
Quite the opposite for my beans. Have always just soaked overnight and then planted out direct, but always always under flat laid mesh to protect from rodents. My runners and main french crop were put in the soil on 8 May, now frosts are for all intents and purposes gone.

Absolutely no propagator needed and many of us  are just sowing them now. You are all right.

Thanks everyone! I've sown again directly in root trainers this time so fingers crossed