Floating row covers

[raisinbran]

Not sure if this is the right place to post. But I am considering floating row covers. My question. Do you heat under them when the temps drop? Nights would be incredibly cold and can't understand how they would do much good without it.
Renee

[Kingtomato]

You must remember, that they won't help if the temps drop too far below freezing. The cold will eventually hurt them. The purpose of FRC is to extend your seasons on each end. For instance, I would never try growing tomatoes in them in Jan.