Hugelkultur, from the German for hill culture, is a method of building a raised bed by piling logs, branches and other woody material into a mound, covering it with organic matter and soil, and planting into the top. As the wood breaks down, it holds water like a sponge, feeds the soil, and creates a warm, fertile mound that can grow vegetables, herbs and flowers for years. It is a good way to use up woody waste, to build a garden on poor soil, and to create a bed that needs less watering once it is established. This guide explains how to build a hugelkultur bed in general terms, what to plant in it, and what its limits are.
The idea behind hugelkultur is simple. A pile of logs and branches buried under soil breaks down slowly, and as it does, it holds water, releases nutrients, and creates air spaces that keep the soil loose and well drained. The mound also warms up earlier in spring than flat ground, because its sloping sides catch the sun, and it gives you more growing surface than a flat bed of the same footprint. In the first year or two, the bed needs more nitrogen than usual, because the wood breaking down uses nitrogen from the soil — this is a well-known effect, and it is why fresh hugelkultur beds are often planted with beans, peas and other nitrogen-fixing plants first, or given extra compost and manure. After a few years, the wood has broken down, the bed settles, and it becomes a rich, moisture-holding mound that needs little feeding.
Building a hugelkultur bed step by step
First, choose a site. A hugelkultur bed suits a sunny spot with room for a mound, because a bed that is about a metre high and a metre or more wide takes up space, and its sloping sides are hard to work from a wheelchair or a chair. It suits a garden with poor, sandy or heavy soil, because the bed is built up from imported material rather than dug into the ground. Mark out the footprint, and if you want, dig a shallow trench about 30 centimetres deep and lay the largest logs in it, so the bed is anchored and the wood is in contact with the soil, where it will stay moist and break down faster.
Second, build the wood core. Lay the largest logs and thick branches at the bottom, then add smaller branches, twigs and woody prunings on top, filling the gaps as you go. Use wood that is already dead or that has been cut and left to dry for a while — fresh green wood breaks down more slowly, and some woods, such as walnut and cedar, contain substances that can inhibit other plants, so avoid them. Do not use treated timber, painted wood or wood from a tree that was diseased, because chemicals and disease can persist in the bed. Avoid large pieces of wood from trees that root easily from cuttings, such as willow, because they can sprout in the bed.
Third, add the organic layers. Cover the wood with upside-down turf, leaves, grass clippings, straw, seaweed or other green material, then add a thick layer of compost and well-rotted manure, and finally a layer of topsoil at least 15 to 20 centimetres deep, so plants have soil to root into. Water each layer as you build it, so the bed is moist throughout. The finished mound should be steep-sided — roughly as high as it is wide — because a steep mound catches more sun and gives more growing surface, though a lower, flatter mound is easier to work on and is a better choice if you are not comfortable reaching up a steep slope. Let the bed settle for a few weeks before planting, if you can, and top it up with soil where it has sunk.
What to plant in a hugelkultur bed
In the first year, plant beans, peas, courgettes, squash and pumpkins, because they are vigorous, they cope with the nitrogen draw of fresh wood, and their large leaves shade the mound and keep it moist. Potatoes also do well in a hugelkultur bed, because the loose, deep mound is easy for tubers to grow in and easy to harvest from. Avoid planting hungry crops such as brassicas in the first year, when nitrogen is in short supply, and avoid planting small, slow seedlings that can dry out on the steep, sunny sides of the mound. In the second and third years, as the wood breaks down and the bed settles, you can plant almost anything: tomatoes, peppers, lettuce, carrots, herbs and flowers all grow well — see growing tomatoes, growing lettuce and growing carrots. Perennial herbs such as rosemary and thyme suit the sunny, well-drained sides of the mound, while leafy crops suit the top, where the soil is deepest. Our raised bed gardening guide covers raised beds in general, and small space gardening covers making the most of a small plot.
Watering a hugelkultur bed needs care in the first year, because the mound drains quickly and the wood has not yet begun to hold water. Water thoroughly and mulch the surface with straw, leaves or compost to hold moisture in, and check the soil with a finger before watering. Once the bed is established, it holds water far better than a flat bed, and it needs watering less often — but it still needs water in a dry spell, especially on the sunny sides. If you are unsure what will grow in a hugelkultur bed in your area, check your local extension service for advice.
Limits and common problems
Hugelkultur is not right for every garden. It takes a lot of material and a lot of work to build, and the bed settles and sinks over the first few years, so it needs topping up with soil and compost. The steep sides can be hard to work on, and they dry out faster than the top, so plants on the sides need more water. The bed can harbour slugs and mice in the woody core, especially if it is built from fresh wood and left undisturbed — check for slugs regularly, and see our slug control guide for organic-first methods. A hugelkultur bed is also a long-term commitment: it is hard to move once it is built, and it takes years for the wood to break down fully. If you have a small garden, a standard raised bed or a keyhole garden may be a better use of space. And if you have a large amount of woody waste but no room for a mound, composting it or using it as a straw bale garden base are other options.
Safety matters when building a hugelkultur bed. Logs and branches are heavy, so lift with bent knees and a straight back, ask for help with large pieces, and use a wheelbarrow rather than carrying them. Wear gloves and eye protection when handling rough wood, and watch for splinters, thorns and insects in old wood. Keep the bed away from buildings and fences, because a damp mound against a wall can cause damp, and keep it clear of paths so the sloping sides do not become a trip hazard.
Common mistakes
The most common hugelkultur mistakes are building the bed too small, so it dries out and does not hold water; using treated, painted or diseased wood; planting hungry crops in the first year when nitrogen is in short supply; not watering enough in the first year; and building a mound so steep that it is hard to work on. Another is expecting the bed to need no water at all: a hugelkultur bed holds water better than a flat bed once it is established, but it still needs watering in dry weather. Build the bed large enough, use clean, dead wood, plant beans and squash first, water and mulch well in the first year, and top the bed up as it settles. A hugelkultur bed is a slow investment that pays off over years, not weeks.
Frequently asked questions
What wood should I use for hugelkultur?
Use dead wood that has been cut and left to dry for a while, such as logs and branches from deciduous trees. Avoid treated, painted or diseased wood, avoid walnut and cedar, which contain substances that can inhibit other plants, and avoid wood from trees that root easily from cuttings, such as willow, because they can sprout in the bed.
How long does a hugelkultur bed last?
A hugelkultur bed can last many years, with the wood breaking down slowly and the bed settling over time. The largest logs may take a decade or more to break down fully, while smaller branches break down in a few years. Top the bed up with soil and compost as it settles, and it will remain fertile for a long time.
What should I plant in a hugelkultur bed in the first year?
Plant beans, peas, courgettes, squash, pumpkins and potatoes in the first year, because they are vigorous and cope with the nitrogen draw of fresh wood. Avoid hungry crops such as brassicas in the first year, and avoid small, slow seedlings that can dry out on the steep sides of the mound.
Does a hugelkultur bed really need less watering?
Once it is established, yes — the wood holds water like a sponge and releases it slowly, so the bed needs watering less often than a flat bed. In the first year, though, the wood has not yet begun to hold water, and the mound drains quickly, so it needs thorough watering and mulching until it settles.
Is hugelkultur suitable for a small garden?
It can be, but a hugelkultur bed takes up space and is hard to move once built. In a small garden, a standard raised bed, a keyhole garden, or a straw bale garden may be a better use of space. If you do build a hugelkultur bed in a small garden, keep it modest in size and site it where it will not shade other plants.