1. Make the starter: Stir together flours, yeast, and water with a rubber spatula in a medium bowl. Cover with plastic wrap, and let stand at cool room temperature until it has risen slightly and is bubbling, 12 to 15 hours.

2. Make the dough: Whisk together flours, wheat germ, seeds, and yeast in a large bowl. Add water and starter, and stir with spatula until mixture comes together in a slightly sticky, loosely formed ball of dough. Cover with plastic wrap, and let rest for 20 minutes.

3. Gently turn dough onto an unfloured work surface. Sprinkle with salt.

4. To knead: Gather dough, lifting it above work surface. Hold one end of dough close to you while you cast the other end in front of you and onto surface. Pull the end of dough in your hands toward you, stretching it gently, then fold the dough in half on top of itself. Repeat: Lift, cast, stretch, and fold. Knead the dough until it is smooth, supple, and elastic, 8 to 10 minutes. Use a dough scraper to clean the surface as needed, adding the scraps to the dough. (Dough will be very sticky, but avoid adding more flour until the end, when it may be necessary to add a very small amount. Add the flour to your fingers, not the dough.) Form dough into a ball.

5. Place dough in a lightly oiled bowl. Cover with oiled plastic wrap, and let rise at cool room temperature for 1 hour. Gently turn dough onto a lightly floured work surface. (Do not punch dough to deflate.) Fold dough into thirds, as you would a business letter. Then fold it in half crosswise. Return to bowl, cover, and let rise until it has almost doubled, 40 to 50 minutes.

6. Gently turn dough onto lightly floured work surface. Spread into a rectangle that's roughly 12 by 8 inches. Fold dough into thirds, as you would a business letter, pressing seams with your fingers.

7. Roll up dough tightly, starting at 1 short end. Gather edges, and gently pull and tuck them underneath the dough to create a round shape, pinching to seal.

8. Place dough on the work surface. Cup hands around dough, and rotate it in circles until a smooth, taut ball forms.

9. Place dough, smooth side down, in a colander lined with a generously floured linen towel. Cover loosely with a piece of oiled plastic wrap, and let rise at cool room temperature until it has almost doubled and a floured finger pressed into the side leaves a slight indentation, 40 to 50 minutes.

10. Place a skillet on oven rack adjusted to lowest position and a baking stone on middle oven rack. Preheat oven to 425 degrees. Turn boule out onto a parchment-lined baking sheet. Just before baking, use a lame or a razor blade to make 4 slashes on top of dough in the shape of a pound sign. Pour 1/2 cup hot water into skillet in oven. Slide bread and parchment onto baking stone.

11. Reduce oven to 400 degrees. Bake, rotating halfway through, until bread is deep golden brown, sounds hollow when bottom is thumped, and interior registers 205 degrees on an instant-read thermometer, 65 to 75 minutes. Let cool on a rack. Bread is best the day you make it, but it can be wrapped in parchment and then foil, and stored at room temperature overnight (or frozen for up to 1 month; thaw at room temperature before serving).