Lemon Grass

Hi,

during the spring / summer of this year I grew some lemongrass from seed. It has grown really well, and is starting to thicken up really well. 

I have put it in the unheated greenhouse at my allotment and wrapped some fleece around it - will this be enough to get it through the winter or will I need to do something else to insulate it against the cold. 

Any advice would be much appreciated.