Hügelkultur: A Permanent Solution To Fertility

Hügelkultur is perhaps the most natural food production system in the Permaculture tool bag. It is an ancient technique of piling dirt on top of future soil.

Simply put, they are creative living systems that slow and store water, increase in fertility as they age, and reduce waste. Best of all, they are entirely sustainable, as their fertility is self-contained.

A Hügelkultur bed is extremely simple to build in theory: pile dirt on top of forest-related and currently decomposing organic matter. As time progresses, the deep soil of the Hügelkultur bed grows in fertility, as its rich organic matter—teeming with soil life—breaks down the woody materials. This decaying process forces the wood to shrink, causing three great long-term benefits.

1. Air Pockets
The decomposing organic matter creates small air pockets within the Hügelkultur mound that allows for aerobic soil life to thrive. In a sense, this function can be likened to “self tilling,” without the negative and harmful effects of actual tilling. Dig into an aged mound and you will find some of the best “sandy loam” and “living soil” this world has to offer.

2. Water Retention
Decaying wood acts as a sponge that soaks and holds moisture deep inside the Hügelkultur mound. This nutrient-rich water then provides years of non-irrigated garden or food-forest crops. Once, we opened a mound and water poured out of it as if it was a spring!

3. Closed Cycle Fertility
Sustainability is fertility in excess. The Hügelkultur technique is a self-contained and long-term system: every year, its fertility inevitably increases due to the natural forces of decomposition and decay. Because the “soil creating” is accomplished below the topsoil, there is no reason to fight the erosion of nutrients; because its “spongy-core” holds moisture, there is much less loss of nutrients into the ground water. In a sense, Hügelkultur mounds actively create fertility and then selfishly hold onto such fertility (ready and waiting to deliver its nutrients to your garden plants).

In a sense, the close cycle fertility of Hügelkulturs create a very stable humus (decomposed organic matter), as its woody carbon compounds (called lignins) resist fast decomposition. This creates a long-term soil-creation system that supplies nutrients both when they are needed and for the length of the system’s life (50+ years).

All of these benefits push the Hügelkultur technique as the true perennial system—composting in place without the recurring energy of human activity.

How To Build Your Hügelkultur

Building a Hügelkultur mound can be as complicated or as simple as you like. The most important aspect of any Permaculture implementation—Hügelkultur included—is the use of local, ethical, and ready resources.
The foundational root of Hügelkultur is the entirely natural process taking fallen woody materials and burying them along with other decomposing matter as though you were father time. Find a northern hill in a forest, where fallen timber is laying on contour with the slope, and you will see Hügelkulturs in the making.

What this means is that your biome and position in that matters. Don’t fall good trees so you can burry them; don’t burry Poplar if your local forest is littered with fallen Maples. Hügelkultur is only natural if you use the resources that are naturally around you.

With that introduction, let’s get Hügel-y!

Important Considerations

Hügelkultur beds can vary in size. Most permaculture designers push for taller bed, ranging from 4 to 6 feet in height. However, there are four items to consider when trying to determine the size of yours: space, resources, time, and climate

The physical space your Hügelkultur bed can take up in your garden or homesite needs careful attention. The bed’s construction is one thing; but the bed needs planted after it is built and these plants also take up both vertical and horizontal space. A wise Hügelkultur Permaculture Design will account for both of these size aspects.

The resource base for your Hügelkultur is of optimal importance. If you only have access to a handful of woody-debris, then you should construct your Hügelkultur bed to accommodate a handful of supplies. Try not to go scouring the local forest for decaying wood and robbing it of its nutrient-cycling and future humus so you can build a bigger and “badder” Hügelkultur bed.

The time consideration is also very important. Hügelkultur beds take time to decompose. Said differently, Hügelkulturs are not immediate fertility machines. If you burry recently fallen Maple, you will get the decay expected of a recently fallen Maple. The more diverse the decay of your woody material will directly affect the diversity of the time component in your bed’s fertility. Burry some rotten wood along with that recently fallen Maple and you will decrease the timeline for your needed fertility (the rotten wood will also aid the decaying process of the Maple).

The last consideration for building your Hügelkultur bed is your climate. The taller your mound, the more spongy organic matter contained therein. If you live in a dry climate that experiences long periods of drought followed by intense precipitation events, then taller a mound oriented to capture and/or slow passing water is a good thing. They can “soak up” and then hold large volumes of water through your droughts.

On the other hand, if you live in a northern climate that experiences consistent low temperatures and large winter storm events, you would be wise to consider designing a mound that is shaped and oriented to provide windless and warmer microclimates.

Steps To Get Hügel-y

Gaia’s Garden has an excellent description of how to build a Hügelkultur:

“To create a Hügelkultur, pile up branches or brush a foot or two deep in a mound 4 to 8 feet long. Stomp on the pile to compact it a bit. Then toss compostable materials—grass clippings, sod, straw into the pile. Sprinkle some compost on the mound, and top with an inch or so of soil. Then plant the Hügelkultur with seeds or starts.”

It is really that easy! It is important to not overcomplicate this process. Hügelkulturs mimic and enhance natural processes … don’t forget that!

  1. Pile the branches and logs you have access to (variable decay stages preffered)
  2. Add organic materials (hay, straw, manure, grass clippings, etc) onto and into the piled branches (the nastier the better!)
  3. Sprinkle compost on top
  4. Add 1-6” of topsoil (depth based off of what you will plant immediately after the build)
  5. Enjoy irrigated free food!

What Is The Best Wood For Hügelkulturs?

The wood you use in your Hügelkultur mound is very important. First and foremost, it needs to be woody debris that is asking to be Hügelkultur-ed. What this means is that it is local, already fallen, and in your way.

That being said, some wood is valued for timber and this wood is generally not great for Hügelkulturs. Black Locust, which resists rot like the plague, is perhaps the worst wood for Hügelkulturs. We want wood that WILL rot and create fertile and rich humus. Other not so great woods are cedar and black walnut. Black walnuts carry juglone, a plant-growth inhibiting compound, and cedars take forever to decompose.

There are many tree species that will work just finely: alder, poplar, birch, maple, oak, willow, aspen, cottonwood, and black cherry (but make sure it is already decomposing), to name a few.

Time To Plant!

Once your Hügelkultur mound is constructed, it is of primary importance to cover it immediately. Loose dirt piled steeply will erode quickly.

Although a good mulch will help curb erosion, getting roots established will help prevent it. Nature’s erosion blocking mechanism (deep root systems) will hold the soil intact while also depositing nutrients back into the system.

In our climate (and depending on the time of year the construction took place), we cast Buckwheat over the Hügelkultur mound and then place the excess moldy hay on top. The hay acts as a moisture retainment, humid, band-aid, and soil-building system that helps the Buckwheat germinate. We typically have excess and moldy hay in the Spring and thus it is a ready resource. Other mulches would do just as well, if not better!

Hügelkultur Example

Hügelkultur Mound Example with branches on contour, holding back erosion and giving the Cover Crop time to establish it rooting mechanisms

To hold the hay intact and prevent the seeds from washing away before generation stables them, moreover, we place thin branches (1 – 4″ diameter) on contour to the Hügelkultur mound’s slope with support pegs below the branches. This keeps the hay tight, the Buckwheat happy, and the erosion out of mind.

Feel free to then plant the Hügelkultur mound with your permaculture design’s berries, bushes, herbs, and vegetables. That being said, we always wait a year before establishing any perennial varieties. Instead, the first year is used to support the system’s fertility by growing and then chopping and dropping nutrient-rich and (most often) Nitrogen-fixing covers: vetch, clovers, lupin, comfrey, trefoil, buckwheat, borage, valerian, lemon balm, bee balm.

Conclusion

Try not to over-think your Hügelkultur bed design—it is just dirt piled on top of future soil.

Remember, you are both mimicking nature and attempting to harness its long-term and extremely fertile rewards. Have fun, get Hügel-y with it, and design what makes sense for your biome and place.

If you need help or have any questions, please do not hesitate to send us an email! We would be happy to answer your questions: daniel@mountarborplantation.com

Written by: Daniel Griffith on May 22, 2019

Leave a Reply

Your email address will not be published. Required fields are marked *

*

Blog

Permaculture

Soil