[SusieB]

My sweet potato is in a wine glass. Can I put it in a heated propagator or will it be too warm?  At the moment it's in my very cold kitchen(about 11degrees).

[Trillium]

Being a tropical plant, sweet potato appreciates warmth, so you can try the propagator and see what happens.
If the potato was sprayed with growth retardant, it might take a long time to sprout, regardless.

[SusieB]

I have just given up on my first sweet potato attempt.  I now have an organic one.  I failed last year, so here's hoping for better luck this year.