Hugelkultur is a German term that roughly translates to “mound culture”. The hugelkultur gardening method has been used in Eastern Europe for centuries and is essentially a sheet-composting method that involves burying woody debris (logs, branches, sticks) and other organic matter under a mound of earth. This gardening method mimics nutrient cycling that occurs in nature. When trees and branches fall to the floor of a forest, they act like a sponge as they decay. That sponge-like property allows the wood to soak up rainfall and then release it slowly into the soil use by surrounding plants. Hugelkultur beds are designed to take advantage of this natural water-retention cycle – so much so that some gardeners who use this method claim they never water at all. (Others say they have to water every few weeks or just once per season.) Wouldn’t that have been a handy drought-fighting benefit this year?
Benefits of Hugelkultur
In addition to water retention, hugelkultur has other benefits. The composition of the bed helps to improve drainage. The use of rotting logs and brush provides a way to turn what would otherwise be a yard work nuisance into a naturally occurring resource. As the wood breaks down, it adds nutrients to the soil and it also leaves behind small air pockets which are essential for root health. (Think of this as the ‘self-tilling’ benefit of hugelkultur.) Decaying wood also attracts worms to the bed, which help to till the soil and leave behind more nutrients as they eat. And in the first couple of years, the bed may provide for longer growing seasons since the massive amount of decomposition happening below will warm the beds slightly. And don’t forget that this is still a raised bed, which means all the benefits of raised beds come into play as well – no soil compaction (you don’t walk on the bed and squish out the air pockets), warms faster in the spring, is more ergonomically accessible (don’t have to bend all the way down to the ground to tend it) and allows for intensive planting (i.e. square foot gardening). [For source info for these proposed benefits, see the list of resources at the end of this post.]
So – at least in theory – using hugelkultur can dramatically reduce my irrigation needs, help me fight back against drought, improve my site drainage, improve my soil fertility, avoid tilling, continue intensive planting and get rid of several unsightly piles of rotting logs that can’t be used for anything useful otherwise? Sign me up!
Challenges of Hugelkultur
So this gardening method has a hip-sounding foreign name and a long list of potential benefits, but there are two sides to every coin. What are the challenges?
First, there’s the initial work involved. Lots of digging and moving of resources like compost, grass clippings, leaves, logs and manure. (Does your back hurt thinking about that, because mine does…) But like a lot of gardening methods that are popular today, the purpose of all this upfront work is to setup a system that can maintain itself going forward with minimal gardener intervention. In other words, more work now and less work later!
Next, there’s the size of the beds. In essence, the bigger they are, the greater the water-retention benefits. And I’m talking notoriously B.I.G. – upwards of six or seven feet tall! That size requires a lot of resource (logs, soil, organic matter, etc.) and could be considered unsightly by neighbors. Of course smaller (2-3 feet tall) hugelkultur beds still have water retention abilities (weeks between watering) but those who claim to go without any water at all love to be called Big Poppa. The enormity of the height can be decreased by partially burying the bed. It is also mitigated by the fact that the bed will shrink in size as decomposition takes place, although I’m not sure how much. You can read more on all of that in the How To section of this post. I know we’re talking about challenges here, but I do want to point out that although there are challenges to a six-foot tall garden bed, the benefits are that you have more surface to plant in and the height makes for super duper easy harvesting (see picture below).
One advantage of a tall hugelkultur bed is that harvesting and generally tending becomes much less of a back-straining task.Image credit: The Permaculture Research Institute of Australia
The next challenge has to do with the type of deciduous (woody) matter used. First, in most of the reading I’ve done, it is recommended that you use big logs rather than a large amount of smaller branches or brush. I presume the bigger logs retain water better. Also, some types of lumber work better than others. For example, you would want to avoid black walnut as it contains a natural herbicide. Other lumber like pine or oak may contain significant tannins that might ‘sour’ the bed. And still others like cedar take a loooong time to decompose and would significantly delay the benefits of hugelkultur. In the case of lumber that contains tannins or takes a long time to decompose, you can avoid most (possibly all) of their drawbacks by using well-rotted wood. For example, pine that has already rotted substantially has probably lost a lot (most?) of its tannin. You would also want to avoid lumber that has been treated as this will introduce chemicals to your garden bed.
The last challenge I’d like to discuss has to do with nitrogen drawdown. Nitrogen drawdown refers to the fact that the logs (which contain much carbon) will need lots of nitrogen to decompose. That means during the first couple of years of a hugelkultur bed, the decomposing logs may rob your soil of some of the nitrogen that would otherwise be used by the plants growing in it. There are ways to mitigate this as well. For starters, using wood that has already been rotting for a while helps. This wood will likely have already taken on a significant amount of nitrogen – so much so that it may now be carrier of nitrogen rather than a taker! Also, adding lots of nitrogen-rich matter to the bed along with the wood will help to feed both decomposition and plant growth. This includes adding manure or ‘greens’ (like grass clippings and table scraps) to the bed. Another way to add nitrogen to the beds is to plant nitrogen fixing crops in it during the first growing season. These plants include crops like alfalfa, clover, rooibos, lentils, beans and peas. And lastly, you can fight back against first-season crop nitrogen deficiencies through natural fertilizers.
How to Build a Hugelkultur Bed
So now that you’ve read the benefits and challenges of hugelkultur, want to know how to build one? It’s pretty easy. The basic steps are:
Create a pile of logs and branches that fits the dimensions of the bed you want.
Add other organic matter such as grass clippings, leaves, kitchen scraps and manure. This step is optional but highly recommended.
Cover the entire pile with soil/compost to create a mound and then mulch the top. Use a mulch that will add nitrogen as it breaks down, like grass clippings or compost, rather than a carbon-rich mulch like wood chips that might take even more nitrogen out as it decomposes.
If desired, you can use logs, rocks, boards, etc. as retaining walls, but these are not necessary.
Here are some optional steps you could insert.
If a super high mound doesn’t work for you, consider partially burying your hugelkultur bed. Dig 2-3 feet down and then start at step one above.
If you’ve dug a trench for your bed, add the freshly dug sod face down on top of the logs as step 3½ before adding soil to create the mound.
If you know where your walkways are going to be, consider digging up that sod as well and placing it on top of your logs. Double bonus – you add nitrogen rich material to your bed AND you don’t have to worry about controlling the grass and weeds in the aisles! (I would mulch the pathways after you dig up the sod so that new weed seeds can’t make your freshly cleared walkway their new home.)
Although you can plant in them directly after creation, hugelkultur beds work best if they cure for a while. As a best practice, build them in the fall for use the following spring. This allows time for some decomposition to take place before you begin planting.
Hugelkultur at Arcadia Farms
As I’ve mentioned, I planned to double the size of the garden in the spring of 2013. I’ve been focusing most of my efforts on converting our existing raised beds to hotbeds for winter growing, and let me tell you, that has involved no small amount of work! I could care less if I ever dig another 2 foot pit again!! (I’m thoroughly sick of digging!) But all this fall as I’ve been digging up earth and replacing it with manure, I’ve been learning about hugelkultur and came to terms with the fact that it would be a beneficial method to use in our garden expansions. Yeah, that’s right – in mid November I decided that it would be a good idea to dig up 1,728 cubic feet of earth before the ground freezes, then fill all the holes with logs and move the dirt back. (Have I mentioned how thoroughly sick of digging I am???) I was convinced this was the best way to expand our garden for all the reasons I’m about to share with you, but I practically fainted at the idea of doing all that digging by hand. (Have I mentioned how thoroughly sick of digging I am??????)
Enter Luka Schemenauer of Schemenauer Farm! Looking at the enormous task before me and the reality of my time constraints, I realized I needed some serious earth-moving machine power to make this work. I looked into renting a bobcat but it would have cost $200 and with my non-existent experience, I imagined it taking ten million years to get the job done. So I hopped onto www.craigslist.org and found Mr. Schemenauer listed as someone who could do bobcat work. He was accommodating, pleasant to work with and has very reasonable rates. (He got the job done for about half the money as it would have been to do it on my own and in considerably less time than ten million years!) If you need similar work done in the southwest Michigan area, I highly recommend him. He also shared a little bit about his farm with me – you should look him up during blueberry season for a great deal on u-pick berries! [Luka (Luke) Schemenauer, 269-214-0837, firstname.lastname@example.org]
I think hugelkultur will be helpful at Arcadia Farms because it:
Is a helpful defense against drought, which was a significant burden in season one
Can potentially reduce our water usage and expense
Can increase our soil fertility
Provides a way to get rid of lots of rotting wood we inherited when we moved here
Costs less than building conventional raised beds because we have most of the resources on hand and don’t need to build retaining walls
Is overall more sustainable than our conventional beds (will require fewer resources in the future)
Some of our site-specific challenges include:
Lumber type – our logs are primarily maple (good) and pine (not as good)
Suburban setting – I imagine that six-foot tall mounds would draw some unfavorable attention and we desire to be good neighbors
Nitrogen draw down – because it’s December already, we have a very limited amount of ‘greens’ to add to the beds to reduce nitrogen draw down. In addition, I don’t have enough manure to add to the beds. The time it would take to find and get more manure is desperately needed just to finish the beds.
Time. It’s December for Pete’s sake! Thank God for unseasonably warm weather, but I’ve got to get a move on if this thing is going to happen, mainly because the ground could start to freeze any day now.
Here’s my plan to take advantage of hugelkultur benefits while addressing our site-specific challenges:
Beds will be buried three feet below ground and raised up approximately two feet above ground. This results in a five foot deep bed that only appears to be two feet tall and that can be added to over time with new organic matter.
Most of our pine lumber is well rotted (at least seven years old, but probably much older) and our maple is two or three years old. This should decrease the amount of nitrogen draw down. Also the tannin should have leached out of the pine many moons ago. Four beds will contain only very rotted wood so that hopefully nitrogen draw down is a non-issue. After that I’m out of really old wood. The remaining six beds will contain newer (2-3 years old) wood so that I can concentrate the limited ‘green’ organic matter I have to those beds that need it most.
Planting in the fall (winter?) rather than spring should get the process of decomposition going, which hopefully means a portion of any nitrogen draw down will take place before I plant in them.
Beds will consist of logs and branches on the bottom, leaves and any greens we have next, topped with upside down sod (from digging up trenches and from the aisle ways) and then a layer of dirt from the holes. In this spring we’ll add composted manure and plant compost for planting in and to add nitrogen. I may also plant some nitrogen-fixing plants in the beds this winter. If we have a mild winter (which I actually hope we don’t!) these will add some nitrogen to the beds as they grow, even if there is no harvest.
To address the time issue, I enlisted the help of an experienced contractor with a bobcat to save me from the dreadful task of hand digging 14 holes that are each 144 cubic feet in size. (Ohh… the thought of it makes me ache…)
Here are some photos of progress so far. I’ll be back with more soon!