How fine the zucchini shreds are is personal preference. Grate the zucchini on the large holes of a box grater, which will make for bigger green flecks in your Zucchini Bread. If you prefer a more subtle zucchini presence in your bread, grate on the smaller holes. Slightly more water will be released when grating on the smaller holes—just discard any excess water. The finely shredded zucchini will blend more seamlessly into the texture of the bread.