I live in Berlin where the winters are very cold. Last winter the snow covered the ground without thawing for 2-3 months. I have two vegetable plots that I want to prepare over the winter by planting green manure plants. Can anyone suggest an appropriate type?
I am not sure about that deep a frost but mustard is a green manuring crop which would be ploughed into the ground in spring. I can only suggest that you ask local farmers in the Berlin area about this as they will know what is suitable for the climate. I know that the conditions in central Europe are much harsher than in the UK. It's the sea and the Gulf Stream that makes the UK climate so mild.