You'd have a very hard time starting a diesel without a block heater. When I lived in Canada I kept an older Ford (a 1949 one!) around for winter use because the diesel tractor was that much harder to start. You can make things a bit better by mixing about 5% gasoline in with the diesel to avoid the diesel becoming flaky but that has limits too and the Canadian winters can throw -40 Celsius at you with some regularity.

Block heaters are a must in that environment.