Hay should be stacked in a stable, well-ventilated arrangement that maximizes protection and minimizes spoilage. Start by placing bales on a flat, elevated surface to prevent direct contact with the ground, protecting it from absorbing moisture from the soil or storm runoff.
Stack the bales to encourage air circulation, such as in a loose, crisscross pattern or with small gaps between layers to promote drying and prevent condensation. Ensure that the stack is slightly sloped or angled to encourage water to flow off the cover. Once the stack is built, spread the hay cover so it extends beyond the edges of the stack so that the hay is fully shielded from the weather.