I was going to include olives but hen reread your post and the reference to very cold winter nights...nevertheless Portugal has some of the oldest Olive trees in Europe.
One I've read about is certified as being more than 2000 years of age. It is on a tourist development, Pedras del Rei near Tavira It can be found between villas 46B and 48A. It is from a variety brought over to Portugal by the Phoenicians in the 7th Century BC from Mesopotamia.
