Hugelkultur - Become a Mound Builder

A hugelkultur bed I designed and built in Argentina, with help from Leigh McIvor and David  LeMay.  The photo was taken by someone at El Jardin de Los Presentes after it was planted.

Hugelkultur is an ancient Eastern European food growing technique.  It has been used for thousands of years to build soil fertility and provide a use for excess woody materials.  This system is great and has an added bonus for northern cold-climate gardeners. As the materials in the mound decompose, a small amount of heat is produced, extending the growing season and helping to protect plants from cold nights.

Here in the North of Superior region, we have an abundance of woody materials that we may often not really know what to do with other than just pile it or burn it. Hugelkultur is here to answer the bell.  Read on to learn how to make some hugelkultur mounds for yourself and the many benefits they provide.

You can make a hugelkultur mound right on top of grass if you wish.  My preferred method though is to first remove the turf, scrape the topsoil away and then weed it.

Next I dig a trench about 30cm deep (1ft.) and a meter wide (3ft.).  The trench collects rainwater that the woody materials will hold for slow release.  You can make this as long as you like.  If it is a longer bed then curve it to follow the contour of the land so it is always level.

Now we line the bottom of the bed with cardboard.  Make sure that it is just the plain brown stuff with vegetable dye lettering.  Do not use glossy, fully coloured and surfaced, heavily glued or waxy stuff.  The worms don't like to eat that as you might well imagine.  Remove all tape and you can remove the staples if you have the patience.  An optional layer of non-glossy vegetable dye based newspaper can be laid down below the cardboard as well.  Now wet these materials well to hold them in place and begin decomposition.  This layer encourages worms to come up and turn the cardboard into worm castings, helps to retain moisture and suppresses roots.

*As you go along through the entire huglekultur mound building process, wet each layer you add.

Gather some old rotten or partially rotten logs or other wood and lay this down to fill the bottom of the trench. Best to avoid using cedar as it takes forever to break down.  Some woods such as black walnut, black locust and black cherry could cause problems with the naturally occurring chemicals they contain.  With our abundance of poplar and birch in the area, best to use these or other such trees as alder, dogwood, pine or spruce.  Alder and dogwood are nitrogen rich.  This thick layer of wood provides multiple benefits.  It retains moisture in the summer and then slowly releases it.  The oft cited example here is that if you go out in the woods in the middle of summer and things are quite dry, just poke into an old log and it will be plenty moist inside.  This organic matter provides plenty of nutrients that nourish all types of life as you can also observe in the forest.  As it breaks down, it naturally tills the soil by creating openings.

On top of the large woody material, we place a layer of brush.  This fills gaps in the bottom layer and gives us a cushion to place further, smaller materials onto. Press down the brush (it could also be corn stalks or any other brush like organic matter) until its spongy and firmly in place.  It will break down faster than the large woody layer because it is much smaller and has more surface area. The center of the mound is aerated from the sides and the criss-cross of the brush provides thousands of air pockets for roots to easily go down into and soil creatures to thrive in.  It also provides excellent drainage while aiding in moisture retention.  A beautiful paradox.

Next we place a layer of partially decomposed compost.  This will feed nutrients into the soil and give a boost to the wood breaking down as well.  It is not as fine as finished compost so it won't all fall down through the spaces between the woodies.  On top of this you place the natural fertilizers you have on hand.  If you have manure, a layer of that is great here.  You can also add a layer of normal kitchen scraps that otherwise would have went to your compost pile as I did.  I gathered some vetch from around the garden site as it is rich in nitrogen and was there on hand and layered this on top of the partial compost and kitchen scraps. A bucket of urine diluted with about nine parts water to one part urine can also add a real boost of nitrogen.

It's now time to put the soil back on top all the while keeping in mind that you want a nice mound shape.

Then add a layer of nice topsoil or finished compost and voila, you are ready to plant or transplant.  Adding a layer of mulch is a great idea at this point. Another option is to construct your hugelkultur mounds in the fall and let them decompose over the winter.  Biochar may also be considered in amongst the large woody layer as it will hold water and nutrients for later release.

I transplanted spaghetti squash into this mound.  All told it only took a couple of hours to make and it's fun because its simple, makes so much sense and is interestingly technical at the same time.  

Plants that are known to do well in hugelkultur mounds are potatoes, squash, zucchini, melons and many types of berries.  There are really many possibilities here.  Blueberries and raspberries are reported to do excellently and are of course abundant in our climate.  Fruit trees are also reported to experience much higher growth in hugel beds.  Adding a low rock wall around the bed offers the additional rewards of heat absorption and radiation, habitat for beneficial creatures, water and soil retention and aesthetic appeal.  I picture a small berry bush forest holding alternating mounds of berries, fruit trees, cucurbits and potatoes.  Hmmm....