Hugelkultur Garden Beds

Posted by on Oct 4, 2016 in Naturalist Blog | 0 comments

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Our latest garden addition is the construction of a hugelkultur garden bed. Hugelkultur, which roughly translates to “mound hill” in German, is a way to combine composting and vegetable gardening together. It is a no till method that can reach up to seven feet tall and can last up to twenty years. Mound gardening is a technique applied around the world. In Eastern Europe and Germany, for instance, hugelkultur has been used for centuries to retain moisture on site, improve drainage, increase soil fertility, and use wood debris. Another example of mound gardening, referred to as swales, was created in 2013 in Makkah, Saudi Arabia. These swales create microclimates which improve the soil, promote drought and salt tolerant plants, decrease erosion, and harvest water from flash floods. Other goals for swales include providing habitat to lizards that eat pests and eventually lead to strips of forest along the deserts.

There are several beneficial components to hugelcultur. If a mound is built up to six or seven feet tall, then watering is unneeded after the first year. Buried within the mound are logs, which will slowly decompose and provide nutrients to the harvestable plants. By having a base layer of wood debris, the mound can also foster Mycelium, the vegetative part of a fungus. Mycelium, besides producing mushrooms which is the fruiting body, decomposes the base log layer, helps plants absorb nutrients, and improves soil quality. Finally, mound gardening is an example of vertical gardening, which saves room by growing up instead of out.

Here is how we did it.

Supplies:

The supplies we used were all treasures that could have been regarded as waste. Over the course of four weeks, a team of Americorp members took out the invasive scotch broom to reduce brush around our buildings. The uncovered limbs and logs from this clearing were brought to this garden to use as the mound’s base. We also used donated rice straw bales from Sierra Fiddle Camp, newspaper, and cardboard from our kitchen. On top we used compost soil that was donated through Recology. When adding it all up, this project had zero production cost.

Construction:

We had to pick a location that would catch water flowing through the garden and had full sun during part of the day. Then Beast, part of our amazing maintenance team, dug a two by five foot trench with a tractor. Beast also put some gravel down at the base of our ditch.

 

Then next day, with help from the Americorps team, we began the layering process. We started with a variety of decaying and fresh logs of ponderosa pine and oak. Then, we put a layer of smaller woody debris, branches, followed organic matter and plant debris, such as leftover tomato plants and bean stalks from the previous season.

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Next came half an inch of newspaper, a layer of overlapping cardboard, and an eight to twelve inch layer of straw. This layer helps activate the decomposition process. By now we are nearly back to the ground level (two feet high) and have added a sprinkle of water between each layer. This is followed by a manure/compost layer of five inches or so, to add nitrogen and support fungus growth.

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Mixing and adding the original top soil with the donated compost soil, we then put on a final inch or two of straw. The straw helps avoid erosion during the rainy season and reduces weed growth until we are ready to plant. This entire process took seven people working the majority of the day.

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The final touches included digging a small trench on the uphill side of the mound to catch water during the winter and sink it into the ground. We also put a layer of wood logs around the base to catch any sliding soil.

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Three Months Later:

Currently the mound still has its top layer of straw to prevent erosion and has sunk at least one foot. We planted four blueberry bushes along the top and found a local species of mushroom. Because the layers of compost soil used in the mound was sterile, the mushrooms are evidence that the interior of the mound is working as intended. Lucky this year’s weather has given Shady Creek a few good storms, and the mound is filled up with water like a tub. During the last few weeks of rain, a small trickle of water sprung, which might mean that we will not need to water it this summer. The mound is already a habitat, and during the dry days lizards skirt in and out. Within the next month we plan to utilize the mound for planting a food forest and using the techniques of companion planting.
Other notes if this sounds good for your own backyard:

Dimensions:

Our mound stands three feet tall from ground level after dropping a foot due to settling, is two feet deep, fifteen feet long, and five feet wide.

Woods that work best:

  • alders
  • apple
  • aspen
  • birch
  • cottonwood
  • maple
  • oak
  • poplar
  • willow (make sure it is dead)
  • Pine is acceptable.

Wood to avoid:

  • most or all  cedars (cypress, redwood, sequoia)
  • camphor wood
  • black locust
  • black cherry
  • eucalyptus
  • tree of heaven (Ailanthus altissima)
  • black walnut (Juglans nigra)
  • California pepper tree (Peruvian and Brasilian)
  • Siberian Elm

 

Amounts:

  • A layer of gravel/rocks (Optional to increase drainage)
  • A layer of logs/bigger branches
  • A layer of branch trimmings
  • Two bales of straw (hay bales have seeds still in them) in our mound rice straw was used, but there are other types of straw that are more nutrient fixing.
  • A layer of: compost, organic matter, manure
  • A layer of top soil mixed in with the ground soil

*note a “layer” varies based on the size you want and what is available around you

Down sides:

Hugelkultur beds are not tilled and we the used rice straw which could reduce nitrogen in the soil. This is why we will have legumes planted will be important an nitrogen replacer.

Because the wood is buried, there is a chance for an increase in termites. It has been hard to find evidence for or against this statement outside of other blogs and personal antecdotes.

Don’t take my word for it, good starting sites:

Permaculture examples:

Thanks for visiting!
Keep checking this blog to follow our progress.

-Rhododendron

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