Preheat your oven to 375°F; grease and flour a loaf pan and set it aside.
In a small bowl, combine the hemp, pumpkin, chia, sesame and sunflower seeds; mix well.
In a large mixing bowl, combine the whole wheat flour, rolled oats, salt and baking soda. Mix with a whisk until fluffy and fully combined; whisk in mixed seeds, keeping about 1 tablespoon to sprinkle over the loaf later.
Make a well in the center of the flour and pour in the buttermilk; whisk gently until the dough becomes too thick and sticky; switch to a rubber spatula and keep stirring gently until the dough comes together.
Transfer the dough to the prepared pan; spread as evenly as you can and sprinkle reserved seeds over the top.
Bake in the preheated oven for 35 to 40 minutes or until a toothpick inserted in the center comes out clean.
Place the pan on a wire rack and let the bread cool in the pan for about 10 minutes, or until it can be handled safely.
Remove the bread from the pan and let cool on the wire rack for another 5 to 10 minutes before slicing and serving.
Keep in an airtight container in a cool dry place for up to a week.