On: Fruit Trenches: Cultivating Subtropical Plants in ...

[pvaldes]

Flying dragon or Poncirus is a must if you want to grow Citrus in cold places. Is the only decicuous Citrus.

The fruits are non culinary, but is an excelent rootstock

In any case the "lemon" of cold places is Chaenomeles (and not all are able to bear fruit).