Hugelkultur Puts Garden Debris to Good Use
Build garden beds with this technique!
Gardeners are taking notice of an ancient gardening technique said to reduce watering, need less fertilizer, improve soil diversity and quality and sequester carbon – all while saving time and money. Called hügelkultur (hoo-gull-culture), a German phrase which translates roughly as hill or mound culture, the central principle combines soil and wood to create a sustainable, low-input growing system that can be adapted to suit various scales and climates.
The original purpose of this centuries-old practice was to repurpose woody material as a soil builder in cold climates. Popularized by Austrian permaculture expert Sepp Holzer, it has been widely embraced in the permaculture community. Now, mainstream gardeners are discovering its benefits, too, amid the challenges of climate change and the rising costs of soil, building materials and fertilizer.
How Hügelkultur Works
The typical hügel is a self-sustaining raised bed, edged or not, built from materials you can likely find at little to no cost.
You start with layering logs and branches at the base, add higher-nitrogen material like grass or weed clippings or manure, and top it with high-quality soil or compost. A commonly cited ratio is 70 percent woody material to 30 percent green material, such as grass clippings, non-invasive weeds or compostable kitchen scraps. Building a hügel sequesters your carbon at home rather than having it picked up from your yard waste bin.
The physical shape of the hügel can foster new microclimates, supporting an intense biodiversity of plants and microorganisms. Moisture-loving plants can grow at the edges where the hügel meets the ground, and herbs like rosemary and sage that prefer drier conditions can sit at the top. If there is a shady side, you can have a longer-lasting crop of lettuces there. Hügels can act as a windbreak or improve drainage and growing conditions over compacted or poorly drained soils, like in urban areas or new building developments.
Much like in a compost pile, as microorganisms break down the woody material, the hügel itself may settle or sink. The longevity of the bed will vary widely based on its materials, the crops being grown on it and the environmental conditions. A small bed may decompose in three years, while farm-scale hügels can last decades. Over time, the balance of nitrogen and the pH of the mound shifts to become more acidic.
Proponents say properly constructed large hügels need next to no supplemental water—even while transforming the harshest environments, from urban streets to deserts or even industrial waste sites, into lush oases. Though they’re often used for food production, experts say you can also grow perennials, flowering annuals, trees and shrubs in a hügel bed. (Trees need to be sited carefully and their roots surrounded by soil.)
In response to people who say they’ve tried this without success, experts note that hügels can take some practice or guidance to get right. Common mistakes are not having enough green material, too many air pockets and having too little soil on top. Just like with a compost pile, you can’t just throw down some sticks and expect to have soil in three months.
Advice from Hügelkultur Experts
Gardeners around the United States are finding new uses and interpretations of the practice.
Paul Wheaton, an author and the permaculture expert behind www.permies.com, says “I think hügelkultur is the most powerful tool in my toolset.”
He has created small-scale hügels in Seattle parking strips. He surrounded his current Montana home with them.
Wheaton trained with Sepp Holzer, and like Holzer, he likes his hügels tall—at least seven feet high if possible. He says this height enables them to go without water for weeks or more at a time.
“I live rurally on hundreds of acres, but where my house is, is basically a giant rock,” says Wheaton. “I built a hügel 11 feet tall and about 8 feet wide. Before, growing a garden there would be pretty impossible, but now I have beautiful, lush, amazing gardens. I have probably doubled my garden space, dramatically extended the growing season and made all my horticultural jobs 10 times easier.”
Wheaton’s method starts by crosshatching woody material together for structural integrity, filling with “blobs” of kitchen scraps, native soil and pulled-up weeds and finally topping with the best soil or compost available. Ideally that will be native soil or homemade compost. He says a “blotchy” build allows for better water movement than lasagna-style flat layers, which can become hydrophobic. He waters his hügels for the first two years to get them established.
If you are starting with poor soil, no worries. It may take a little longer, but the microbiome will come. Wheaton recommends planting potatoes to get started, which are not heavy nitrogen feeders.
California-based environmental designer Leigh Adams starts with sunflower plantings both to “activate” her beds with roots that will aerate compacted soil, and to have something beautiful growing while the hügel builds enviable tilth.
Adams’s interest in hügelkultur began with noticing that when a tree falls, new microbial life returns not where the tree stood, but where it fell. Adams created a hügelkultur demonstration garden at the Los Angeles County Arboretum & Botanical Garden in 2015, during the worst drought in the county’s history. The administration was skeptical and planned for the garden to last one year. Yet it still stands today, boasting four hügels on one acre. As an example of a water-saving regenerative landscape, it’s a main attraction.
“The oldest is 11 years old, probably close to 50 feet long and it was over 6 feet tall when it was built. Now it’s maybe 4 feet,” says Adams of the garden’s hügels. “It’s covered with native plants and trees that have never been watered,” which is quite a feat in Los Angeles. More than three dozen native bee species have been counted feeding there.
She says she is inundated with requests for hügels in her work with regenerative design firm Studio Petrichor. In another project, she is using hügelkultur in a soil remediation project of brownfields adjacent to the Los Angeles River with Metabolic Studio–with the help of fungi.
“By using logs and biomass and inoculating those with specific fungi, we can undo some of the damage and also restore carbon to the soil,” she says, noting that carbon means water in the soil, which means life.
Her method involves excavating soil on-site and layering pieces of clean cardboard (without staples) with green waste before topping with soil. She also uses large logs on top, but stresses they are held in place with exterior terraces of stone and smaller logs; otherwise, they would not be safe. “Dancing” on the hügel with each layer is a crucial step toward building a strong structure, she says. She doesn’t recommend placing them on hillsides, because if not well-stabilized they can become hazardous in floods.
Branching Out With Hügelkultur
Leigh Adams says a colleague proposes a new name for all the permutations of hügelkultur: “Carbon Culture.” For instance, Adams says you can adapt hügelkultur principles to raised beds and other containers, keeping the proportions of materials in mind. She has installed hügels where there was no soil, atop asphalt in a school garden.
Permaculture author and instructor Matt Powers digs his hügels into ground trenches, tamping down well to discourage animals from nesting in air pockets.
“It’s pretty critical you bury it deep enough with a clearance of a foot and half to three feet of dirt,” he says. “You can grow just about anything, but it’s influenced by the soil you put on it.” To jumpstart the breakdown of nutrients, he inoculates all his mounds with fungi. The turkey tail mushroom is a favorite that works in many areas of the country.
In Burlington, Wash., flower farmer Sarah Wagstaff has been growing her crops in hügel beds for more than ten years. At her SUOT Flower Farm (which stands for Small Units of Time), her hügels overflow with woody shrubs, dahlias and perennials as well as herbs like rosemary, oregano, breadseed poppies and sage. These are sold in bouquets and bath salts and harvested for seeds. She started with hügel beds totaling less than an acre and is now scaling up on a new 66-acre property in the fertile Skagit Valley. The first hügels incorporated natural materials collected on site from windfall and chipped cedar boughs.
Wagstaff looks forward to experimenting with hügel hedgerows—pollinator-friendly mixed-shrub borders traditionally seen edging farmland in the United Kingdom.
“There are so many benefits to hedgerows,” she says. “They offer windbreak and habitat. Anytime there is an edge, there is an abundance of diversity and life. If I can create refuges and shelter belts to attract many different species, it will encourage wildlife to continue, to linger, to thrive.”
One of the superpowers of hügels is their long-term impact, she notes.
“I’m not planning for this year alone. I’m planning for seven to ten years down the road. I’m purposefully including trees that will take many years to decompose in the berms and plants that take many years to mature.”
