Preheat oven to 400 degrees F. Use about 1 tablespoon of the butter to thoroughly grease a 6.5 inch (measured from top to to) cast iron skillet. Set aside.
In a mixing bowl, combine the flours, wheat germ, cream of tartar, baking soda, salt, and sugar. Stir well so that everything is evenly distributed. Add the second tablespoon of butter and and mash it into the flour mixture. Stir in the caraway.
Add the buttermilk and use a heavy duty scraper or a spoon to stir mixture into a soft dough. Turn onto a lightly floured surface and knead 10 times or just until mixture is cohesive, but still a little bumpy. Don't knead until smooth, or the bread will be tough.
Shape mixture into a mound just large enough to fit in the greased pan. Using a razor or a knife, cut two slashes in the top.
Bake for about 45 minutes or until well browned. Internal temperature should be about 190 or a little higher. Let cool for about 15 to 20 minutes before serving.