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What is a Hügelkultur raised bed?
Hügelkultur, which roughly translates to “mound culture” in German, is a long used, permaculture method of gardening that consists of layering wood debris and organic material to form a hill or mound that is planted into directly. This method of piling wood debris aims to mimic the natural process of nutrient cycling that occurs in uncultivated forest habitats. The process of building a Hügelkultur raised bed uses the same method of layering to fill raised planter boxes rather than piling right on the ground. There are many benefits to this method, which is why it’s still used all around the world today.
Why use the Hügelkultur method?
- Saves a significant amount of money by filling the majority of your raised bed with logs and branches rather than having to buy a ton of soil.
- Fertilizes the soil as the wood continues to break down over time and release nutrients.
- Retains moisture as the logs and branches soak up water then slowly release it back into the soil.
- Improves drainage when soil is healthy and aerated by the decomposing organic material and water is absorbed by logs and branches below.
- Proven to increase crop yields with much less maintenance.
- Good way to make use of any rotting branches or logs you may have laying around.
How to set up your Hügelkultur raised bed:
There are a few different ways to create a hügelkultur raised bed, but the key is just to build a base of decaying wood and then pile layers of organic material on top. I wanted to make use the materials I had on hand, so this is the method that I went with:
Layer 1: Cardboard
If your raised bed has a built-in bottom, this layer is not necessary. The cardboard just helps to create a barrier that will smother grass and weeds beneath it and will naturally decompose over time. Make sure to remove all tape and staples when breaking down your cardboard. Do not use colored cardboard, as it contains dyes and a is usually coated in a plastic film, so it will not properly break down. A single layer will work fine, however two layers will be a more protective barrier against weeds attempting to poke through.
Layer 2: Rotting logs
Hardwoods, such as oak, maple, aspen, birch, alder, cottonwood, or poplar are best to use because they will easily break down over time. I happened to have a pile of oak logs laying around that I was able to make use of for this project.
Layer 3: Sticks and small branches
Pile a layer of branches and twigs on top of the logs. (Unfortunately, I failed to capture a photo of this layer.)
Layer 4: Mulch
Next, pile mulch onto the logs and branches and fill all the spaces in between. There are many types of mulch you can use, including rotted hay or straw, grass clippings, wood shavings, or even wood chips. I have a giant oak tree in my front yard that dumps TONS of leaves each year, so that was an obvious choice for me.
Layer 5: Compost
The combination of mulch and compost creates a nitrogen-rich layer that helps to balance the carbon-to-nitrogen ratio throughout the decomposition process. If the compost has had time to fully decompose into it’s humus state and is not too hot or potent for plants, then it is safe to plant directly into, and you can skip the final layer of topsoil.
Layer 6 (optional): Top soil
If fresh, hot compost was used in the previous layer, then it is too potent to safely plant your seeds or plants in and therefore, a final layer of top soil is required.
Time for planting!
As you can see in the picture below, I wasted no time before starting to plant in my new bed! I ran out of topsoil and didn’t even have the back half of the bed finished, but needed to get these strawberries planted ASAP. So, once you complete this project, go ahead and get planting as soon as you’d like!
Hügelbed vs. Ordinary Raised Bed:
I did a little experiment to determine just how much the Hügelkultur method actually works in terms of improving soil health and plant growth and the results were way more apparent than I expected. Unfortunately, I never took pictures to compare, so you’ll have to take my word for it. I built two raised beds, using the Hügelkultur method for one, and only filling the other with a base of leaves, then compost and top soil. Since I built an arch trellis between the two, I planted the exact same climbing plants in each bed across from each other. Despite the fact that the ordinary raised bed was exposed to sunlight for a slightly longer period, the seedlings planted in the Hügelkultur raised bed grew significantly faster and were visibly larger and healthier. You just can’t argue with results like that!
Things to watch out for:
- Diseases and pests that could be hiding in the rotten logs, such as termites or certain fungi.
- Type of wood is very important. Avoid using wood from allelopathic trees, such as black walnut and cherry as they may release chemicals into the soil as they break down that interfere with the growth of other plants. Also, avoid wood that is resistant to rot, such as cedar and black locust, as well as wood from trees that easily spread and could send up new shoots, such as willows.
- Avoid treated wood of any kind because it has antifungal and antimicrobial properties that will not only inhibit decomposition, but also leak dangerous chemicals into the soil.
- Be sure to source organic materials, so that you do not introduce dangerous pesticides into your new garden bed.
- If using fresh wood instead of rotten, there will be less nitrogen available for plants as the wood begins to break down during the first year, so consider using a nitrogen-based fertilizer or plant nitrogen-fixing plants such as legumes.
Tips for success:
- If using planter boxes made from wood, line the inside with plastic to protect it from deteriorating. (I failed to do this and very much regret it!)
- Water each layer as you go and try to compact the material as much as possible to help with decomposition and to make sure there are no large air gaps.
- Pile the bed as high as possible because the layers will sink over time as the wood debris continues to break down. More compost will need to be added each year to maintain the soil level.
Where to source materials:
Cardboard: This can be completely free of charge! Try asking around, either to friends and family, or even by calling local stores and warehouses to see if they have any laying around. If you’re having trouble finding some, another option is piling paper bags, newspaper or contractor paper. I’ve even seen some people use sheets of wool they had available.
Logs and branches: If you don’t have any wood that you can safely source from your own yard, try asking around to see if anyone you know has some laying around. Rotting logs are preferable since they have already begun breaking down, but fresh wood is perfectly fine if that is your only option. The decomposition process will just take a bit longer.
Mulch: Fallen leaves are certainly the cheapest and easiest option in my opinion. If this is not available to you, rotted hay, grass clippings, wood shavings, or wood chips are also great options for mulch and can easily be sourced free of charge by contacting your local arborist for a drop off, or by ordering through ChipDrop. (Always be sure you know where the wood is sourced!)
Compost and Topsoil: Depending on how many beds you’re filling, you can either find these in bags at your local hardware store or garden center, or buy in bulk to save money. Just check the internet to find a local facility that provides bulk deliveries or pickups. Here in Lane County, Oregon, I get my bulk deliveries through Lane Forest Products, so that’s who I would recommend if you’re local! Of course, you can always use homemade compost if you have a supply.
Tools to help get the job done:
Below is a list of tools that I used during the process that can help save you time and energy, none of which are completely necessary:
- Wheel barrow for moving heavy logs and branches.
- Hand saw for trimming down thick branches.
- Shovel for moving compost and soil.
- Gardening gloves to protect your hands.
I hope that after reading this post, you feel confident in using the Hügelkultur method for your raised garden beds to produce beautiful, healthy plants to feed you and your family for years to come. This sustainable, low maintenance method is one that I will use and advocate for as long as I live and hope that others can experience the same benefits! Leave a comment down below if you have any questions or want to share your experience. I’d love to hear from you!
Sources:
- Luo, Qing Lana, Casey Hentgens, and Carmen Wright. 2020. “Sustainable Landscapes: Creating a Hügelkultur for Gardening with Stormwater Management Benefits.” Division of Agricultural Sciences and Natural Resources : 1–8.
