Hügelkultur: A Rotting Resource
Written onAugust 17 , 2016
Hügelkultur is a centuries-old sustainable method of building raised garden beds in a way that mimics the natural succession of the forest floor. Hügelkultur (the word is German for “mound culture”) utilizes existing biological resources and natural processes to turn often-unused biomass waste into efficient, small-scale intensive systems. An ideal solution for areas with poor quality soil, Hügelkultur beds can support seasonal vegetable gardens, perennial plants, fruit trees, shrubs, or brambles and can be built on flat ground or below grade in trenched beds.
The foundation of a Hügelkultur bed is always wood, while the top layers can be comprised of grass clippings, raked leaves, various manures, mowed vegetation, compost, or topsoil—organic materials readily available and typically free or low cost. The gradual decay of the woody base creates rich humus, encourages the growth of beneficial mycorrhizal fungi, and promotes microbial activity, leading to increased resistance to pests and diseases, and better nutrient absorption. The decomposing organic matter creates heat and the rotted wood becomes sponge-like and maintains a consistent soil moisture level.
The concentration of nutrients encourages deep, strong plant root growth and leads to increased productivity and greater yields over time with little or no additional input. Once established, Hügelkultur beds should not require tilling, fertilization, or irrigation.
Sounds like magic, right? For those patient enough to wait for it and willing to invest the labor up front, the benefits are well worth it. Site preparation should begin in the fall, and planting should happen the following spring. You will need an ample supply of wood or woody debris. I had access to wood chips from a tree trimming service but you could use branches, rotted logs, scraps from your woodpile, or any wood really, with the exception of painted or pressure-treated lumber. I would also recommend not using cedar, black walnut, and locust as they are known to be allelopathic and contain natural plant toxins.
Site your Hügelkultur beds in full sun for best results, and don’t hesitate to make your beds wide and high (I formed beds 2 feet wide and nearly 18 inches high). I had an area brush-hogged and used the mowed vegetation for the critical nitrogen layers on top of the wood chips; I also added copious amounts of chicken and horse manure. It is not absolutely essential to cover your Hügelkultur beds with topsoil as long as the wood base is covered with compostable materials (or overturned sod in the case of trenched beds.)
And that’s it. Then you wait. The slow composting of the woody material will cause the beds to collapse somewhat, and the wood will consume nitrogen as it composts, but the beds will be fine to plant in come spring. The long-term slow release of nutrients and the increased fungal population of the soil in your Hügelkultur beds will build soil fertility and provide optimal growing conditions for many years to come.
Click on photos to read the captions.