Hugelkultur is really a long - German for 'hill culture' - word to describe composting in place, which gardeners have been doing for generations, but layering the matter to be composted in a specific way to conserve moisture in the soil as well as providing slow-release nutrients for plants.
It is also a good way to use woody waste - logs, brushwood, twigs - that might otherwise go on a bonfire, now that many of us are trying to move away from burning waste, specially in built-up areas.
The photo at the top shows a finished hugelbed, planted up. They make an attactive garden or allotment feature in their own right; you could design a lovely curved hugel bed to add contours to your plot.
Constructing a raised bed using hugelkultur principles
Ideally you want to dig down to the water table, but 30-45cms is a good depth, the deeper the better. The trench should be wide enough to take good-sized tree logs, but not so wide that you won't be able to reach to the centre when it's built - no more than a metre. This will also give you room to bank up the sides gently.
2. Start filling the trench, first with the larger logs, branches, woody waste. If the wood has already started to rot a bit, then so much the better. Try not to use green wood which might start to sprout. The kinds of wood that you are likely to be cutting down or pruning on an allotment or in a garden such as ash, beech, birch, apple, pear, cedar and other conifers, are all suitable for a hugel bed.
3. Pack the logs in as tightly as you can, even chopping them up a bit so they fit if necessary.
4. The next layer to go on top is the brushwood, smaller branches, twigs, etc.
5. Next, pack into the trench any more organic matter you may have: straw, green leaves (not whole weeds), seaweed, if you live near the coast, mulch, leaf mould, grass clippings, anything tht might normally go on the compost heap.
7. Now turf the bed, the surface of which should now be at least at ground level if not slightly raised. This turf should in theory be the turf that you initially dug out of the ground to create the footprint of the bed. Lay it 'upside-down', ie, with the grass on the underside and the topsoil uppermost. This forms a firm base for the bed.
8. Add a top layer of compost, about 8-10cms thick. You should now have a gently mounded raised bed, ready to sow or plant into.
At this point, I have found that for purely practical reasons, my hugel beds have been more stable if I give them wooden sides as with a conventional raised bed. So they are not strictly orthodox, but the principles are the same.
How it works
The logs on the bottom layer absorb water, and once saturated, slowly release it, along with nitrogen and other nutrients as the logs slowly break down. The smaller branches and greeen waste break down more quickly into composted organic matter, feeding your plants.
The turf layer also breaks down, giving you a nice fine topsoil tilth to plant into. The top compost layer gives you a good starting point.
Hugelkultur - pros and cons
+ sustainable and inexpensive - uses readily available - and free - materials;
+ provides slow-release nutrients for plants;
+ as the woody materials and organic matter breakdown, the process generates heat and warms the bed, giving you better germination and extending the growing season;
+ reduced need for watering.
+ provides slow-release nutrients for plants;
+ as the woody materials and organic matter breakdown, the process generates heat and warms the bed, giving you better germination and extending the growing season;
+ reduced need for watering.
- labour-intensive to set up and build;
- benefits may not be apparent the first year as your hugel settles down and continues to absorb nitrogen;
- banked sides may need support.
- benefits may not be apparent the first year as your hugel settles down and continues to absorb nitrogen;
- banked sides may need support.
Having tested this out on the blueberries, last year I built a second hugel bed for the blackcurrant bushes grown from cuttings taken the previous year. Once everything was in situ, we then went through a three-month drought in the summer of course. The plants in the new hugelbed struggled a bit - they were very young cuttings, after all, but in the established blueberry bed, I managed to get away without having to water them at all, and they survived.
Further reading
https://www.permaculture.co.uk/articles/the-many-benefits-of-hugelkultur/ - The Many Benefits of Hugelkultur
