Permaculture in Action: Hugelkultur
Of course, I am not making soil according to nature’s recipe which includes minerals, organic matter, water, and air.
What I am creating with hugelkultur is an improved growing medium made by recycling multiple natural ingredients that compost to create nutrient-rich soil.
Hugelkultur is a great example of an earthwork design that utilizes several permaculture principles:
- Catch and Store Energy: recycling forms of energy contributes to a circular/closed-loop system of energy. The HG beds also retain moisture and heat, important energies in a garden.
- Obtain a Yield: producing soil is the ultimate yield!
- Use and Value Renewable Services: make the best use of nature’s resources
- Produce No Waste: recycling debris for nutrients
Hugelkultur, (from German, meaning “mound or hill culture”) is simply a raised bed that mimics nature’s natural processes of growth, recycling, and decomposition. The process is similar to the floor of a forest, where organic debris falls and slowly rots into the soil. It’s basically passive composting. Hugelkulter is a type of sheet mulching using woody plant debris as the foundation for the bed. This short animation offers a nice visual.
Benefits of a Hugelkultur Bed
- The design recycles woody and herbaceous plant debris, making this an eco-friendly design. Other household materials like cardboard, newspaper, and even natural fiber clothing can be added/recycled.
- Purchasing soil to fill large raised beds can be expensive so using woody waste to partially fill raised beds saves money.
- The woody base slowly recycles nutrients through the process of decay, building a nutrient-rich growing medium. The release of the nutrients can last for a decade or longer depending on the type and size of the wood used.
- Incorporating wood as a layer is one way to sequester carbon.
- The woody debris retains moisture, requiring minimal irrigation, and increasing drought tolerance.
- The process of decomposition creates a warmer microclimate allowing earlier planting, at least during the first couple of years
- If planted with perennials, the wood maintains open spaces for roots to reach.
My garden produces a considerable amount of plant debris, most of which I compost either directly onto garden beds (chop & drop), or move to compost piles. Two-thirds of my land is forested with large conifers, bitter cherry trees, and vine maple shrubs. A tree or two is harvested each year for firewood, leaving behind branches and bark. Conifer firewood often sheds its bark when being split, creating a pile of woody debris that is not useful for burning for heat.
My first hugel bed was made with trunk chunks of hardwood I found lying under some shrubbery. After a few years of chopping firewood, I had a large pile of bark debris that formed the second base of my second hugel bed. I’ll describe how I made both beds and then discuss their current status.
What kind of wood can be used for hugelkultur?
The type of wood you use for the beds is important. Softwoods like apple, alder, poplar, dry willow, cottonwood, and birch are generally best. Harder woods will take much longer to decompose which can be a good thing for a permanent bed. Conifers are softer but contain tannins. Tannins will initially inhibit the nutrient recycling cycle including the desired development of a healthy habitat of microorganisms.
Avoid eucalyptus, cedar, or cypress because of their acidity and/or anti-fungal, anti-microbial properties. Black walnut should not be used because it contains the toxin, juglone, which inhibits plant growth.
How To Build a Hugelkultur Bed
- Dried and/or rotting tree trunks, large branches and/or bark, logs
- Chopped firewood & wood ash
- Kitchen and garden waste
- Woodchips & sawdust
- Soil & compost
- Straw & spoiled hay
- Manure (fresh will make the bed hotter the first years)
- Cardboard (for weed suppression at the bottome
- Select the location. It should be considered a permanent garden bed. Hugels can be made in both sunny or shady locations; location depends on what you want to plant in the hugel bed. They can be traditional rectangle beds but circular and quarter moon designs would also work. Move all of your materials to the site.
- Dig out the bed to a depth of about 8-12 inches, reserving the soil for the mound building.
- Put a layer of cardboard down which helps with the inoculation of the composting process.
- Lay the woody debris as the first layer. The more wood you put in, the longer the bed will actively decompose. It’s recommended that the woody debris and logs be soaked overnight. I didn’t have a container to do that so I soaked the wood layer, using a hose. The moisture will help start the decomposition.
- Add a layer of fresh prunings or manure to provide nitrogen to activate the composting process. This layer can be as big as you want (creating a mound). Add more water by soaking this layer.
- Top the bed with the soil you removed. Adding aged compost and manure will help with the inoculation process.
- Top with straw or wood chips. Let sit for 4-6 weeks before planting in it.
- As the wood decomposes, it will gradually shrink (this takes years). Add manure, compost each year, and consider growing a cover crop (then chop and drop it before it goes to seed) each spring.
Hugels are built as a raised bed, creating a sheet mulched mound as tall as you want. I tried this with my first attempt but found it difficult to water what I planted because the water ran down the sides of the mound. You can avoid this by building more of a tiered mound that has some flatter surfaces or using sticks inserted vertically to hold drip irrigation or a seeping hose.
A hugelkultur bed is an active compost pile so its nutrient and humus levels will change each year. That understanding should influence what you plant in it. Some good choices for hugelkultur beds are culinary and medicinal herbs and crops like blueberries that prefer acidic soil.
Current Status of my Hugel Beds
My two hugel beds are located in my fenced vegetable garden and next to each other. The first bed is made with old rotting tree chunks of unidentified hardwood. This bed has hosted annuals like sunflowers, dahlias, and summer squash. Last year, I planted thornless blackberries in it. I created a trellis system using 3 fencing bars and wire to support their growth. Unfortunately, I think that gophers were able to tunnel through the side of the hugel and chew off the three blackberry starts I had planted. This year, I am planting tomato plants in the bed to take advantage of the trellis system.
The second bed was an experiment. I utilized the huge pile of mostly conifer bark debris from the firewood cutting shed. I added back the dug-out soil, rotted willow, garden prunings, aged horse manure, compost, and straw. I let this sit for a year and then transplanted a row of tomatoes the following summer. Then, one morning, I came out to two holes where tomato plants had been planted. Gophers! The bark pieces did not create a strong enough barrier. I am not sure what I will do with this bed. The gophers are persistent and I believe I will need to invest in framed raised beds.
Or move. Gophers make me think about moving.
Hugelkultur can easily be utilized in framed wooden or metal raised beds. It’s really about the benefits of recycling woody debris and creating a microclimate. Below is a photo of framed hugelkultur bed at a local community garden. It’s planted with perennial herbs.
I recently purchased two metal beds for my L-shaped herb/pollinator garden and will build a hugelkultur system within the beds by simply filling the bottom half with woody debris that is strewn all over my homestead. This reduces the amount of soil I need to fill these two beds and will provide a warmer home for my herbs.