In the permaculture world, there is a group that are hugel or bioswale purists. A hugel “has to be” at least 3 ft tall. A swale “has to be” a depression filled with plants. Why is mine both?
This is the interesting thing about what I built. I dug slightly deeper than needed for a hugel bed, as I am on a slope, and physics demanded buried wood so a heavy rain wouldn’t carry away my hugel, as wood can float. So I created a swale. I filled the dug out with wood, branches, brush, kitchen scraps, compost, topsoil and mulch. I made a hugel! I immediately planted both annuals and perennials on it, the purpose being to further assist catching water on the slope of my yard. Well, hugels should “never” be on a slope like mine, so it’s back to being a swale. Yet, the soil is definitely above ground in a mound. That’s a hugel. Yet still, in a few years, my earthwork will likely sink into a slight vegetative depression. A bioswale.
The fact is, where you place your earthwork, the size of your earthwork, the purpose of your earthwork and the materials you use to construct it are all variables that can put your bioswale or hugel in either category.
Let’s take a quick look at some reputable sources of info on both concepts.
Per to USDA definition: BIOSWALE – Bioswales are storm water runoff conveyance systems.
Per the MSU Bioswale Factsheet – The benefits of a bioswale include:
- Protects local waterways from stormwater pollutants
- Creates habitat for wildlife, including birds and butterflies,
- Reduces non-point pollution by filtering stormwater
- Reduces standing water (puddles) that can attract mosquitoes
- Creates colorful gardens with a variety of flowers and plants year round
- Requires little maintenance after establishment
Currently, a hugel is whatever the most recent popular creator, Sepp Holzer, says it is. Throughout human history, we have been burying plant and tree refuse and repurposing that land. Sepp Holzer has made it his mission to advocate for and educate people to use various agricultural strategies that are Earth-friendly. His hugel builds are 1-2 meters high. The base is either ground level or slightly below (dug). The base is logs and other large plant debris, covered with dirt and then planted with native plants.
I have a vegetative hugel bioswale.
My Reasons for Building a Vegetative Hugel Bioswale
- I had some wood taking up space in our yard. Our plan was to build a fire pit, yet years later, no fire pit, but we had saved a great deal of wood for one.
- Our home is on a hill. One section of garden, down slope, holds water more then the others. To prevent that area from collecting too much water, I built the hugel bioswale parallel to that garden.
- I thought it would be neat to build a hugel and see if it added value to a suburban garden.
How to Build a Hugel Bioswale – With Photo Diary
Choosing the location for your hugel type bioswale is a critical decision that may require additional research on your part. I don’t think anyone can tell you where it will do the most good unless they can see where it will go, have knowledge about your particular soil type (clay or sandy soil), have an understanding of the function of the earthwork you want to build, the size of the earthwork you desire and a great deal of other considerations.
I chose my location as I needed a small water catchment parallel to a garden that was holding water during downpours. I also chose this location as it made sense with all the other features (trees, gardens) in my yard.
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It’s always a good idea to step back and take a look, after every few feet dug out, to make sure you are going to be happy with the look and placement. Save that sod! It will go back onto the hugel bioswale, after the wood. For easy filling, place dug sod on one side of the dig, and loose soil on the other.
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Why ten inches down? I dug down far enough where the wood and branches would be at and below soil level, so sudden flooding would be unlikely to carry off my hugel. Putting a tall hugel on a slope is a risky move, so I avoided that problem with a deeper trench and lower height than a “traditional” hugel.
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I made sure to get the edges fairly evenly dug. The biggest pain was the digging.
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Add the largest wood pieces to the bottom of the dug out. Avoid wood that hosts toxins, i.e. Black Walnut. This a stage of the build where it’s critical to research what you have and if it’s best for a hugel bioswale. Sepp’s website is a great place to start (link in Sources).
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I added more branches and brush, from thickest to thinnest. Once added, I stepped in it, danced on it really, to push the level of woody product below the soil line. I walked around my yard and grabbed my trimmings from pruning, branches, dead parts of plants…any non-toxic wood product.
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I added the soil back to the dig. Stomped all over it to settle the dirt into the gaps among the woody pieces.
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Sod goes back onto the hugel bioswale. Dance on it a little. As my build was not going to be tall, I wanted a flat base of dirt.
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I did another walkabout my garden, pruning tomato and other plants. Grabbed some kitchen scraps too.
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Added a couple of bags of topsoil and homemade compost to the top of the hugel bioswale.
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Final step before planting was adding a thin layer of grass clipping mulch. Once the hugel bioswale is planted, then more mulch was added.
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The entire physical build time of the hugel bioswale was about three hours, including the scrounging for filler materials. The dimensions of the build are approximately 14″ wide x 23′ long x 10″ deep and about 10″ tall above ground.
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I planted squash, spinach and bean seeds in the hugel the day after the hugel was completed. Six weeks later, all had blossoms. Plants were large and strong. I also had puffballs. No surprise as a hugel bioswale is a great home for fungi.
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This article is written about a year after the build. I did a bit of research, made the decision and am very happy with it. You can undo most smaller hugel bioswale builds. Probably won’t be fun nor fast, but it’s likely you can revert to yard or garden if you made a mistake. I love to experiment, but I won’t lead someone else down Curious Road without knowing more about you. Hence, I can’t recommend a hugel bioswale, only show you what I did and why and let you go from there.
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Sources:
USDA INFO BIOSWALES – https://www.nrcs.usda.gov/wps/portal/nrcs/detail/?cid=nrcs142p2_008505
MICHIGAN STATE INFO – https://www.canr.msu.edu/news/bioswales_can_improve_water_quality_resources
SEPP HOLZER’S WEBSITE – http://www.seppholzer.info/huegel-culture-design/
The End