Will flowers live if you cut them down for the winter?

Question

I want to cut my flowers down to the grass top but someone told me the cold would kill them. What time of year should I cut these back?

Answer 1

What kind of flowers are you talking about?  Do you have annuals or perennials?  

Answer 2

day lillies will come back and so should the angel trumpets.

Zinnia's, marigolds, petunias, have to be planted every year.