Hugel-what now? Don’t let the fancy German intimidate you. In fact, hugelkultur — which translates to “mound culture” — is a more intuitive, sustainable and just plain easier way of creating a garden out of readily available resources than many of our traditional methods. As such, this method is readily employed by permaculture enthusiasts.
So try abandoning the cookie-cutter, 4-by-8-foot, raised beds for a season and consider setting aside a plot for a hugelkultur experiment this year.
An organic process
Picture a self-watering garden system where your soil actively decomposes to create its own fertilizer and the resultant heat generated brings an extended season of vegetable crops.
A composting mentality is at the heart of this method, meaning it helps to consider the carbon-to-nitrogen ratio when creating your bed, which is usually 25 to 30 parts carbon to one part nitrogen. “Brown” carboniferous material constitutes the woodier yard debris, like logs, branches, shredded cardboard, leaves and straw, while the “greener” nitrogenous ingredients include manure, food waste, grass clippings, seaweed and hay.
So start by collecting a wide range of organic material in the brown and green categories, but try to avoid material from potentially allelopathic tree species like black walnut and cedar. If possible, it is helpful to source more rotten pieces of wood than freshly cut.
Once you have your materials gathered, measure out your bed. Since most hugelkultur beds need to start out 3 feet or more (they shrink as they decompose), the standard width is 5 feet. Some gardeners decide to make their beds shorter than 3 feet and, as such, opt for 4 feet of width.
With your location settled, begin to create a layer or two of the largest biomass (logs) to make the lowest layer of the hugelkultur bed. One option is to dig a shallow trench 6 inches deep to house the base layer, which isn’t necessary but could potentially assist in the decomposition process.
Next, add a layer of small twigs, sticks, shredded cardboard and other carboniferous material with high surface area. At this point, take a break to soak all of these layers thoroughly with water from a garden hose.
With your woody material thoroughly doused, locate your kitchen waste, manure and other nitrogen-rich materials, and insert them into the gaps between logs and branches. Cover all that with an inch or two of garden soil, and finally, top it all off with a layer of mulch.
The end product may look a little awkward, but let the whole bed “cure” for at least a couple months — even better if you can prepare the bed in the fall and plant in spring or prepare in winter for midsummer planting.
At this point, you can sow seeds or plant starts directly into the hugelkultur bed just as you would with a normal plot of soil.
As the wood breaks down at the core of the bed, not only will the bed shrink to a more manageable height, it also will release the water contained within to become available for crops. Usually, by the second year, the bed is completely self-watering.
Furthermore, because the decomposition process releases heat as a byproduct, the soil temperature will be warmer than that of surrounding native soil. We found a great example of this phenomenon last December at Picardo P-Patch in Wedgwood. During an extended frost, a hugelkultur bed didn’t have a cloche, yet boasted a healthy crop of perky kale (and verdant weeds), while the rest of the kale in exposed beds — where the soil had frozen — was wilted from the cold.
A word of caution: You might consider buying a flat-bed truck before starting your hugelkultur adventure, because once you build your first bed, you’ll see the world through fresh, new eyes and discover potential hugelkultur materials everywhere you go. Half-rotten wood never looked so good!
To learn more about permaculture gardening or clear up any confusion about hugelkultur methods, contact the Garden Hotline at (206) 633-0224 or visit www.gardenhotline.org.
KATIE VINCENT is an educator for Seattle Tilth’s Garden Hotline (seattletilth.org). To comment on this column, write to MPTimes@nwlink.com.