Preheat oven to 350°F. Grease 9x13- inch baking pan.
In a medium bowl, stir flour, wheat germ, baking soda, cinnamon, salt and nutmeg: set aside. In a large bowl, combine apples, sugars, oil, walnuts, eggs, and vanilla. Add flour mixture; stir gently until well blended Pour into prepared pan.
Bake for 50 minutes or until cake pulls away from sides of pan. Cool on wire rack. Sprinkle with powdered sugar before serving if desired.