How to Build Hugelkultur Raised Beds
Hugelkultur is a German word that means mound culture, although I have heard others say it means high bed. To be simple, it is basically soil over wood. Hugel beds can be any size, use different sizes of stumps and branches, and different decomposition stages of the wood & different types of wood.
Benefits of Hugelkultur
-Little irrigation is needed after saturation as the wood holds a tremendous amount of moisture.
-No fertilizer is needed as the wood releases nutrients slowly as it decomposes.
-The benefits of tilling are realized as the wood decomposition creates air pockets, but without the soil destruction and work of tilling.
-Lots of beneficial fungal activity
-Depending on the height of the beds, harvesting can be easier as you do not need to bend over quite as much.
-Lots of microclimates are created by the raised hugel beds. For example, your plants that require shade can be planted on the north side, while the sun plants can be planted on the south and west sides. Also, plants preferring drier conditions can be planted toward the top, and plants preferring wet conditions towards the bottom.
Plants that do Especially Well in Hugel Beds
You can plant just about anything in your hugel beds and they will do well, but there are certain plants that tend to do very well in a hugel bed.
-Potatoes (Regular and Sweet)
-Cucurbit Family (Cucumbers, squash, watermelon, zucchini etc…)
How to Construct Hugel Beds
1. Decide on the size you require. Remember the hugel beds will shrink down by 25% over the first year or so.
2. Decide on a location. Make sure the area gets sufficient light for the plants you wish to cultivate. Be wary of water flows, as you do not want to divert surface water with your berms to areas that may cause damage to property.
3. Figure out where you are going to get your wood, and what type it is. Certain woods are allelopathic such as black walnut or don’t break down very well such as black locust. Other woods such as conifers are acidic. Allelopathic wood should be avoided as it will be toxic to other plants. Conifers can be used, but it would be a good idea to plant acid loving plants such as blueberries in that part of the hugel bed. A little of these types of woods is not a problem if mixed.
4. Be certain on the location and shape of the beds, as they will not be easily moved. Straight beds are boring, try curved beds for aesthetic purposes as well as the many microclimates it will create. Mark this out. I painted out where I thought the hugel beds would extend to, and I also marked where I wanted to place my wood, which would allow the soil to cover the wood well. I planned my mounds to be about 55 inches wide, with a wood core of about 24 inches wide. My planned height was about 30-36 inches, with about 12-18 inches high of a wood core. Be careful not to use too much wood. I think no more than 40% of your hugel beds should be wood.
5. Lay out your wood directly on the ground, or dig the area out putting the soil aside to be applied on top of the wood. I prefer laying the wood directly on the ground as it is much less labor intensive. It does require bringing in more soil though. Sepp Holzer typically uses an excavator, so he will remove the sod, dig out the area, and then place the wood in the trench. After that he places the turned over sod on top of the wood, then sub soil, then the topsoil, and finally compost. He likes to build his beds very high and very steep, so sometimes he takes brush and then leafy branches and spikes it into the side to act as erosion control and cover for his seeds.
6. Add fill, leaves, turned over sod, or any other organic material.
7. Add subsoil, then topsoil and lightly tamp.
8. Add a good layer of compost & lightly tamp.
9. Plant immediately. If you are not ready to plant your hugel beds yet, at the very least install an annual cover crop to hold the soil. You can use an annual pea or bean to help to build the fertility in the soil. I used Dutch White Clover as perennial living mulch for my hugel beds. I plan to plant berries, potatoes, melons, squash, cucumbers, and probably quite a few other plants I’m not thinking of at the moment. It has been said that Dutch White Clover should not be planted amongst annuals as it will crowd out the desired annuals. For delicate annuals such as lettuce I would agree, but for large seed such as potatoes, onion bulbs, and beans, I think they may have a reduced yield, but many of the plants will thrive. Any perennial shrubs will exist very happily amongst the clover. I think overall the clover will be a benefit to the other plants in my hugel polyculture as it provides nitrogen, mulch, and pollinator and beneficial insect attractors. I may have to stress the clover by scalping it down to allow certain plants to compete successfully.
Variations on the Hugelkultur Bed
One of the things I love about permaculture is that you can combine concepts and stack functions. For example, I wanted to incorporate some hugel beds into my zone 1 garden beds for certain plants. I also wanted to have sun traps in my zone 1 garden to help some of my tender annuals deal with late frosts in the spring, and early frosts in the fall. So I decided to turn my hugel beds into sun traps. All I had to do was make the hugel beds in the shape of a horseshoe with the opening facing south. This allows the sun in and holds it while blocking the cold from the north. I am also planning to plant perennial shrubs at the top of the beds to increase the effectiveness of the suntrap.
Another idea I am planning to incorporate into my design for the next swales that I dig is to add wood downslope of the on-contour swales just before I dump the soil for the berms downslope. This will effectively change the berm to a hugel bed with very minimal additional work.