Hugelkultur Mounds

Here is the eastern half of my backyard before I began the process of building five hugelkultur mounds. A significant amount of time went into preparing this part of the yard. Two rose bushes and numerous bulbs had to be relocated. The most intense work went into removing the stumps of two previously chopped down huge bushes.

Many people when building hugelkultur mounds will dig up any sod, put it aside, and then put it upside down as one of the top layers. Because the top soil in the North End of Tacoma is contaminated with heavy metals, I decided it was best to just leave the sod in place and build my mounds on top. To kill all the grass I gathered a crazy amount of cardboard (a community effort, thank you everyone who contributed!!!) and blanketed the area.

The first stage of building the mounds was to layout a base of large logs (see the Materials page for more details about the types and origins of the wood).

The next stage was to add medium sized logs and all different sized branches.

After recieving a chip drop (see the Materials page for details), I then spread a really thick layer of arborist wood chips in the pathways between the mounds.

I added the last bit of wood chips on top of the mounds to try and fill in the gaps, and then added the first layer of TAGRO Mix (see the Materials page for details). TAGRO Mix is 50% biosolids (humanure), 25% sawdust, and 25% screened sand. According to the TAGRO website it’s comparable to steer manure.

Next I added a layer of saw chips (little bits of wood in between wood chips and saw dust in size). I was able to get them for free through the Craigslist free listings.

A second layer of TAGRO Mix.

Next a layer of rotting leaves. I don’t have any large trees in my yard, but my neighbors were more than happy to let Sara and I rake up their leaves the prior fall. I compressed them down in plastic totes, so even though it doesn’t look like a lot of leaves the layer you see is actually really dense.

A third layer of TAGRO Mix.

A layer of mostly finished compost (see the Materials page for details), full of beneficial microbes, worms, and other insects. I also applied homemade worm tea to further innoculate the mounds.

Sudan-sorghum grass (a summer cover crop) seeds were broadcast over the four long mounds and were then covered with a thin layer of aged black bark (also from The City of Tacoma’s TAGRO program though it is just bark, no biosolids). The back mound recieved a thicker layer of aged black bark and dragon’s blood sedum seeds were planted on its crown.