The concept of a permaculture garden is to provide long-term solutions that maximize outputs and minimize inputs, while cycling energy and resources through the system. This creates closed-loop efficiency within your system and prevents excess waste. In fact, one of permaculture’s most favored sayings is ‘there’s no such thing as waste, just things in the wrong place’.
Hugelkultur is a great example of recycling resources on your site to create long-term fertility in the soil. In doing this, you create beds that become more productive over time, helping to produce better quality crops with higher yields.
But what is Hugelkultur and why should you be implementing it in your permaculture garden this spring?
What is Hugelkultur?
Hugelkultur literally translates from German as ‘Hill culture’. In short, it refers to mound style garden beds that are higher than regular raised beds. The bottom layer of these beds is filled with buried logs as a source of long-term nutrients to the plants.
When we’re building our permaculture gardens, especially in late winter and early Spring, we often find we have logs, branches, and sticks in abundance from pruning our fruit trees. Rather than leaving these resources to go to waste, Hugelkultur makes excellent use of these carbon-rich sources of nutrients.
The logs that are buried at the bottom of the beds which then slowly decompose over time. This creates humus (decomposed organic matter) at the bottom of the beds.
The thing about wood is that it contain lignans – these are carbon fibre compounds that help to build the structure in the wood. These are slow to decompose giving a far more stable humus, as well as breaking down over a much longer period of time.
As permaculture designers, we aim to provide solutions not only in space, but also in time – this is one that that lets us set it and forget it, knowing our plants will get a healthy source of food for a long period. In fact, Hugelkultur beds can provide nutrients for several years, whereas compost and mulch on the topsoil needs to be constantly replaced.
The Benefits of Hugelkultur
The advantages of hugelkultur spread over many years. Not only does Hugelkultur retain water and provide long-standing nutrients, it also helps reduce waste on your site and cycle energies.
The humus that is created begins feeding the plants directly from underneath. This encourages roots to reach down and anchor further into the soil, mirrored by larger growth above the ground. This helps grow stronger, healthier crops that produce a more fruitful, higher quality yield.
What’s more, the spongy composition of the humus on the lower levels also helps to retain water. It can absorb water and hold it for far longer periods of time, and at lower levels. This reduces the chance of the water being evaporated by the sun and allows access to stored water in drier seasons.
Again, it also encourages the roots to reach down further and support the plant’s strength and growth. Many permaculture gardeners that use this technique say that they do not need to ever water their Hugelkultur beds after the first year (unless in very arid climates).
The breakdown process, where the logs turn to humus, produces heat. The heat keeps the soil warm, protecting against frost in the colder months. This extra heat contributes to faster crop growth and more bountiful yields.
Hugelkultur is a no-dig method of gardening, which means that aside from being far less effort, it also doesn’t disturb the complex ecosystems that form within the soil.
Even when we make compost and put it on our topsoil, the act of moving the compost will disturb these intricate universes – often letting in large amounts of oxygen that burn up the nutrients – which then have to start rebuilding again when laid on the soil. Hugelkultur prevents this from happening as it stays under your beds for years without disturbance.
Hugelkultur helps to recycle nutrients and energies through your site in a productive and eco-friendly way. Often we end up burning excess branches and twigs that are pruned from trees. While this can produce ash (which is good for the garden and ash beetles) it also releases carbon back into the air. By using Hugelkultur beds, you’re sequestering the carbon the trees sucked out of the air during their lifetime.
The mound-like structure of the bed also provides you with more planting space than flat beds or small raised beds.
As you only have to do this process once every few years, this really reduces your labor and materials inputs while providing you with more and longer outputs through years of crop cycles.
How To Build Hugelkultur Beds
It’s relatively simple to build Hugelkultur beds. These beds allow for a range of flexibility when it comes to the materials you can use, which is important as the best nutrient providers for your soil tend to come from the local environment in which the beds will be built.
In this sense, try to look for logs and branches from your own site with which to build.
What Type of Wood Should I used for HugelKultur?
While you can use any trees for Hugelkultur, hard woods break down more slowly (which is why they’re used for furniture!) and will provide nutrients over a longer period. You’re looking to use trees types such as apple, alder, maple, oak, poplar, and acacia. Careful to make sure everything is fully dead so it doesn’t start sprouting under the soil.
You can get a head start by introducing a few logs from softer woods that break down faster, which will allow you to gain nutrients in the short-term too. These softer woods, along with smaller twigs and branches should be added at the top of the log pile to give the new plants nutrients as they begin growing. Equally, you will want a mixture of tree types as this will ensure that you have varied nutrients within the soil.
Tree Types to Avoid in Hugelkultur
There are some tree types that should not be used when building hugelkultur beds. This is because certain species of tree contain toxins and are allelopathic – meaning they inhibit the growth of other plants. For example, most permaculturists know never to plant apples next to walnuts, because the walnuts inhibit the apple tree’s growth – the same principal applies to Hugelkultur beds.
Equally, some trees like firs and pines release tannins into the soil. These can turn the soil very acidic, as well as leaching into water supplies.
Trees to avoid include camphor wood, black locust, eucalyptus, black walnut, Siberian Elm, California pepper tree, black cherry, and pretty much all cedar varieties. You can use fir and pine if it has been aged, but try to break it down into smaller parts first, and layer it close to the top with a good mix of other woods.
What Else Do I Need?
You will need some form of mulch to go on top of your log layer. Just like sheet mulching, you want to use the lasagne layering pattern to layer green and brown material on top.
You can use anything from leaves to grass clippings to kitchen waste for your green layer, while straw, hay, dried leaves, and corn husks make a great brown layer. Remember to make sure you have mixed materials for the mulch as to provide a range of nutrients. If you need more instructions on mulching, click here.
You will also need come pre-made compost. You can buy it from gardening stores (make sure it is organic), but it is usually best to use your own as it will consist of plants from your native environment and works toward recycling energies back.
How Do I Build My Hugelkultur Beds?
Firstly, you need to locate your beds. When building any kind of garden beds, we try to build on contour – meaning that we build the bed parallel with the lay of the land.
Imagine a map with the red lines that indicate steepness – you want to build along those lines. This keeps the beds level and stops water from running down slopes you may create by going against the contours.
Secondly, you need to consider the sun’s aspect. If you are creating tall beds one next to the other, you want the sun to travel across the length of the bed. Otherwise, plants on the northside will get far less sunshine.
If this is unavoidable, you need to consider plant selection, with more shade-loving plants on the north side of the mound. However, planting the beds from east to west will give you better sun throughout the day.
Next, after measuring your bed out, you want to start digging to make a trough to lay your logs into. Dig around 30-60 cm (10-20 inches) into the ground. The width is entirely at your discretion, however structurally, the wider the bed is, the taller you’ll be able to build it, creating more surface area.
It is important to remember though, that the bed will widen out further than the trough you have dug, as you’ll be building material on top. Generally, gardeners tend to dig the trough about a foot to a foot and a half wide. This will create a bed that is 2-3 feet wide in the end. Any larger than this and you’ll struggle to reach the crops at the center of the bed.
When fully built, the base should be 2-3 times wider than the top of the mound and the height should be about the same as the width.
Remember though, that if you create a bed that’s 3 feet tall, and the plants grow another 3-4 feet tall, you may have trouble reaching the fruits and vegetables. Some people incorporate logs to stand on at the edge of their beds, or a border that’s raised to help them reach.
Place your logs into the hole. You want to get as much wood as you can in, without packing it too tightly. Make sure you mix up the wood types to give a varied soil.
You can pile the logs up slightly higher than the trough to help define the pyramid shape that the bed will eventually work out to be. Smaller branches, twigs, and soft woods should be at the top, with your bigger tree trunks, branches, and hardwoods at the bottom.
On top of this layer, you want to add mulch. Interestingly, some people place turf upside down here. It helps to hold the structure, and the green material sparks the decomposition process of the carbon by introducing nitrogen.
While this is a good idea, you shouldn’t go out and buy turf; but this can be a useful way to recycle resources if you’re removing an old lawn or have some laying about.
Layer your mulch on top to about the same height as the wood – 60cm (23in) at the lowest, but the more mulch you put, the more compost will build below the surface, providing super healthy soil and a rich and complex ecosystem. Make sure your mulch (especially the brown layers) are moist as this will get the decomposition process underway immediately.
On top of your mulch, you need a layer of compost. Spread it liberally on top, but you won’t need more than 10-20cm (4-8cm) of compost, as the whole process will be making more underneath.
Now you need to cover the whole lot in the soil you removed from the trough. The soil will provide an insulative layer, like a clay oven; absorbing thermal mass and getting the process started. The soil also stops weed seeds from finding their way into the super nutrient compost and taking over.
You can plant in your bed immediately. Just dig into the soil, pull back the other layers and plant seeds and seedlings straight in.
At a glance…
Hugelkultur is one of the most effective ways to cycle back nutrients into the soil. Not only does it provide a rich and complex soil for your plants to grow, Hugelkultur beds increase surface area and retain more water than a regular garden bed could.
In this sense, you’re reducing water and wood waste, as well as sequestering the carbon from the air of your site, and replacing it into the soil.
Hugelkultur is an exceptional way to create healthy beds that provide plant food for a really long time – several years in fact – while reducing water consumption and giving your plants a real boost.
You can use your beds for many years to come, reducing the need for more labor and materials each year. Instead, you just chop and drop at the end of the season, cover crop over winter, and replant again in the summer. Unless of course, you’re planting perennials – then you can just leave the beds to produce tasty crops for years!