Preheat oven to 375 degrees F (190 degrees C). Grease muffins tins, or line cups with paper liners.
Sprinkle 1/4 cup flour over blueberries, and stir to coat berries thoroughly.
In a small bowl, whisk together 2 cups flour, baking powder and salt.
In a large bowl, cream margarine, and gradually mix in sugar. Beat eggs, and stir into creamed mixture along with vanilla. Stir in milk alternately with flour mixture, mixing well after each addition. Fold in berries. Fill muffin cups 2/3 full with batter.