I am growing 'Sub Arctic Plenty' tomato for the first time this year. It was a freebie packet last year with one of my gardening magazines. I became interested in this area last year when I found out about a tomato breeding project in Quebec, Canada where they have a series of cold tolerant beefsteak tomatoes! A little research has shown me that this variety was developed in the 1940s to enable the US Servicemen posted in Greenland to grow their own vegetables in such a Northern climate in order to stay healthy. Sub Arctic Plenty sets fruit even in cold conditions and is claimed to be the very first tomato to ripen outdoors.