By Kim Robson:
Hugelkultur, pronounced “Hoo-gul-culture,” is a German word meaning hill culture or hill mound. It has been practiced in Germany and Eastern Europe for hundreds of years. Hugelkultur is comprised of no-dig raised planting beds that can hold moisture, provide nutrients and maximize surface space in small yards. They are perfect for growing fruit, vegetables and herbs.
Hugel beds are like layered composting without the stirring. Simply layer logs, branches, leaves, grass clippings, straw, cardboard, newspaper, manure, compost and other biomass into a mound; then top with soil and plant your garden.
The bottom layer of wood gradually decays and provides a consistent source of long-term nutrients for the bed. A large bed can supply nutrients for upwards of 20 years (or even longer if you use only hardwoods). The composting wood also generates heat, which keeps the bed naturally warm well past the end of the normal growing season.
As the logs and branches on the bottom decompose, soil aeration increases, meaning the bed requires no tilling in the long term. Hugel beds also trap carbon in the soil and trap moisture. The logs and branches act like a sponge for rainwater, which is stored and slowly released during drier times. After the first year, you may never need to water your hugel bed again, except during long-term droughts.
Ready to try it? If you have a grass lawn, hugelkultur expert Sepp Holzer recommends cutting out the sod, digging a one-foot-deep trench, and filling the trench with vertically-placed logs and branches and wood chips. Then cover the wood with the upside-down grass turf. Over the turf, add grass clippings, seaweed, newspaper, aged manure, straw, green leaves, mulch, etc. Top with a layer of compost.
Holzer recommends building hugel beds as steeply as possible (more than 45 degrees) to avoid soil compaction from increased pressure over time. Steeper beds also provide more surface area for planting, and the height makes them easy to access for harvesting. This hugel bed was supported with old wooden pallets.
Straw bale gardens are another option that require less soil and less water, and generate heat as the straw breaks down nutrients to feed the plants. For an area with poor quality soil, surround a hugel bed interior with straw bales, and top with lasagna layering.
Lasagna gardening (aka sheet mulching) is like composting with layers. Click here to see a suggested plan for sheet mulching layers. Nitrogen-rich material such as fresh grass clippings, seaweed, worm castings, straw, dead leaf litter, or green leaves layered on top of the hugelkultur wood helps jump-start the composting process.
During the hugel bed’s first year, the breakdown of the wood (and growing fungi) steal a good measure of the nitrogen from the surrounding bed, so you’ll want to add nitrogen during that first year. You could also plant crops like legumes that add nitrogen to the soil, or plant crops with minimal nitrogen requirements, unless you placed plenty of organic material on top of the wood. After the wood absorbs all the nitrogen it can, it starts to break down and release nitrogen back into the system. Ultimately you’ll end up with a fertile bed of nutrient rich soil.
A hardwood base layer breaks down more slowly and will, therefore, last longer and hold water and add nutrients for more years. But softwoods are fine, too; they will just disintegrate more quickly. Mixing hardwoods on the bottom with softwoods on top then adding branches and wood chips over that is a good plan that will give off nutrients right away. The newly decomposing softwoods at the top will eat up a lot of nitrogen, though, so be prepared to compensate for that.
Woods that work best include
- Willow (Make sure willow is dead or it will sprout.)
Other acceptable woods could include
- Black cherry (use only rotted)
- Camphor wood (well aged)
- Cedar/juniper/yew (antimicrobial/antifungal, so use only at very bottom or unless already well aged)
- Cedar (should be broken down before new plant roots reach it)
- Eucalyptus (slightly antimicrobial)
- Osage orange (exceptionally resistant to decay)
- Pacific yew (exceptionally resistant to decay)
- Pine/fir/spruce (watch for tannins and sap)
- Red mulberry (exceptionally resistant to decay)
Woods to avoid are
- Black locust (won’t decompose)
- Black walnut (juglone toxin)
- Old growth redwood (heartwood will not decompose and redwood compost can prevent seed germination)
Want to learn more? Permaculture Magazine issue no. 68 can be downloaded as a pdf file and contains lots of excellent tips. Hugel beds can also be built on a small scale in a tub. Holzer also has advice for building vertical beds in urban spaces. Finally, this YouTube video shows the entire process, step by step: