Hügelkultur Bed. Hügelkultur is a raised plant bed built over decaying wood and compostable materials. A fallen tree becomes a “nurse log”, decomposing, releasing nutrients, and nourishing new growth above for years, even decades. As the wood decays, it becomes more porous, storing water like a giant sponge, and releasing it slowly back into the bed’s soil. This means less plant watering; some gardeners report their beds thrived all season from rainfall alone.