A hillside property can undoubtedly be very attractive. When it comes to use and processing, inclined positions present owners with labor-intensive and often cost-intensive challenges. However, there are numerous different options that you can use to secure and attractively secure slopes.
Principles of slope reinforcement
Fixing a slope on the property is advisable for several reasons. On the one hand, the fortification protects the steep ground from gradual sliding due to gravity and erosion. On the other hand, the steep surface can also be made much more usable through certain fastening methods by creating unusual places to stay and increasing the overall area and diversity of your garden.
The following factors are always the basis for fastening:
- Inclination of the slope – necessary statics
- Orientation of the slope
- Personal style ideas and ecological demands
Inclination of the slope – necessary statics
How steep the slope to be fortified is roughly determines which types of fortification are suitable. The steeper a slope is, the more structural devices it requires for the necessary statics. For example, for a stable retaining wall on slopes with an inclination of around 7° or more, concrete foundations must be built and drainage must be installed at the bases facing the slope to drain rain and meltwater flowing down.
Orientation of the slope
The orientation of the slope is more of an aspect that can be used to explore usage options. A north-facing slope can perhaps only be pragmatically secured against slipping, but on a south-facing or western-facing slope it is worth considering combining the fortification with horticultural or recreational use. Depending on the desired utility value, it also depends on whether the solution should be cheaper and simple or more costly and labor-intensive.
Personal style ideas and ecological demands
Last but not least, your personal style preferences are essential when choosing the type of fastening. Because such a slope reinforcement is something that is permanent and should not break with the character of your existing garden. So choose a variant that won't become a thorn in your side.
Also, listen to what ideal direction you want to take in your garden tour in the future. Because no matter how ecologically valuable the solution will be, it will pay off, especially in the long term.
A slope attachment can be ecologically and visually valuable for the garden
Slope fixing options
There are a whole range of options for securing a slope. Here is an overview of the methods and their advantages and disadvantages:
| Planting rings | Wooden palisades | Gabions | Drywall | Planting | Prefabricated concrete elements | |
|---|---|---|---|---|---|---|
| Advantages | optically diplomatic, diverse planting options | simple, cheap, familiar look | relatively uncomplicated, modern look | romantic-authentic flair, diverse living space | natural, ecologically most valuable | (mostly) can be built without an excavator |
| Disadvantages | relatively complex construction | moderate holding power, susceptible to moisture damage | moderate stability, susceptible to rust, building permit | Statics challenging, possibly building permit | only for flatter slopes, relatively complex, requires intensive care | Foundation, drainage & building permit required |
Planting rings
Planting rings are a stylistically diplomatic and versatile option for fixing a slope. They offer a solid fastening effect thanks to the stone material, but can create a very decorative and natural final appearance when planted.
The grooved rings or rectangular shapes made of lightweight concrete are stacked on top of each other like stairs on the slope. In order for the whole thing to remain stable and not collapse, a certain amount of preparatory work must be done in the form of excavating earth and a concrete foundation. In addition, rain and meltwater must be able to drain away. As drainage, a layer of gravel is placed on the slope, i.e. under the planting stones.
The construction is relatively complex but worthwhile: because the plant rings can be turned into an attractive design element with a variety of plants. A colorful, perhaps unusual mix of ornamental and useful plants is particularly recommended. This can be easily achieved in the many substrates that are close together but still separated from each other. If your slope is not too far from the kitchen, the plant ring slope is also ideal as a living herb shelf.
Planting rings are a beautiful, simple option for attaching to a slope
Wooden palisades
For slopes with a moderate inclination, wooden palisades are a very attractive and comparatively inexpensive mounting option. They bring a warm, familiar character and are fairly easy to set up.
The disadvantage of them is their moderate support and their susceptibility to moisture damage. For good stability and water drainage, you should place the palisades a third of the way deep in a trench bed filled with gravel and lean concrete. In order to prevent the palisades from prematurely rotting above the critical recessed section, you should also choose pressure-impregnated versions made from robust types of wood such as fir, pine, oak or tropical woods. Nevertheless, you usually can't avoid replacing the palisades after a few years.
Walls
Walls can be used to fortify a slope particularly solidly - but their construction also requires solid work. So that they fulfill their particularly supportive function and do not become a danger, they must be anchored in the ground so that they cannot tip over. This is especially true for heavyweight walls.
Heavyweight Walls
As its name suggests, a gravity wall is a weighty comrade. Gravity walls are walls made of bricks or solid concrete modules. Gravity walls are a structural construction that always requires a building permit.
With their large mass, gravity walls can withstand even difficult, particularly steep slopes with dense soil. So that it is not crushed by the slope itself and in danger of tipping over, a gravity wall is sunk deep into the ground in a concrete foundation to at least a third of its total height. Concrete modules for building a gravity wall have a base whose thickness is approximately one third of the module height. They have a supporting wedge at the front edge and flatten linearly in height at the front. As a result, they literally lean against the slope mass.
Drainage is very important for solid walls that do not allow water to pass through. To ensure that rain and meltwater can drain away easily, dig a second trench behind the foundation trench, fill it with a gravel bed and, if necessary, lay a drainage pipe in it. Make sure that the drained water seeps away on your property and does not flow into neighboring properties or public spaces.
It is particularly easy and quick to build a visually clean heavyweight wall with formwork stones. The hollow, rectangular concrete elements are usually manufactured according to a simple support system with normal and corner or end stones and are simply filled with concrete on the inside for solidification.
Gabions
Gabions securely hold back even steep slopes
Gabions are actually also heavyweight walls, but we will treat them separately here because of their special style. Gabions are currently very trendy with their straight-lined, puristic look. For those who generally follow a very well-maintained, tidy garden style, the walls loosely layered in metal frameworks are also ideal for fixing on a slope. They are relatively easy to erect, but offer slightly less stability compared to a plastered wall. Depending on the federal state, you must also obtain an official building permit for all types of wall construction.
Especially when they are used to secure slopes, gabion walls need sufficiently deep anchoring to the ground in the form of a concrete foundation. Drainage is also urgently needed. If moisture accumulates and freezes on its lower back base and in the spaces between the stones in winter, the wall is in danger of tipping over at some point due to the ice load. To prevent water from getting between the loose gabion stones and instead draining away properly through the gravel bed, it is recommended to insert a strip of fleece at the back base of the masonry.
Drywall
Drystone walls are also heavyweight walls with a special character - that's why an extra word about them. With a dry stone wall or a construction made up of several dry stone walls arranged in terraces, you can create a natural and southern-looking flair in the garden. Especially as a natural stone wall with uncut natural stone, such a building exudes an authentic, homely character. Depending on the stone you choose, you can create a cottage garden style or a Mediterranean flair. In addition, thanks to its unplastered joints, a dry stone wall offers many ecological niches for an entire biotope of small fauna and spontaneous growth.
Building a dry stone wall on a small scale is certainly possible without any special expertise, but it does require a little patience and a lot of design love. Especially with natural stone walls. The uncut and therefore irregular natural stones have to be put together like a puzzle to create the best possible fit that can withstand the forces of the slope and the weather. A dry stone wall over 1.20 m high should have a concrete foundation. For even taller structures, static calculations are required - you should consult an expert at the latest.
Prefabricated concrete elements
Prefabricated concrete modules mean palisades or L-stones made of concrete. They are usually rather low and save a lot of mass compared to heavyweight walls thanks to angled base supports. Such concrete blocks are therefore more suitable for flatter slopes.
The construction of slope supports with L-stones or concrete palisades does not really require any less effort. Here, too, you have to pour a concrete foundation and set up drainage in the form of a gravel trench. In most communities, a building permit must also be obtained for constructions with prefabricated concrete elements.
Planting
Plants hold the soil firmly and prevent the slope from slipping
You can also use plants as a natural way to fortify slopes. Trees, bushes and perennials use their roots to secure even the steepest slopes in the wild. In the garden, however, fastening with plants is only useful with moderate slopes of a maximum of 7°. For anything steeper, terraces with solid retaining walls are more recommended.
The planting method has many advantages. On the one hand, you can make your slope quite attractive with trees and perennials. On the other hand, it creates more valuable habitat for garden fauna.
Wood plants, i.e. shrubs and smaller trees with well-branched roots, are suitable for macro fastening. It is best to first create a rough “net” with gaps for intermediate planting. Ideally, you should combine shallow and deep roots.
Shrubs and trees that provide good soil stability and are decorative at the same time include the following:
- Privet
- buddleia
- fingerbush
- Cornelian cherry
- Broom
- Shrub roses
Ground cover plants are ideal for micro-fortification, i.e. the strengthening planting of the open ground areas between the trees. Above all, they stabilize the immediate surface of the sloping reach and protect against erosion. When it comes to ground cover, you should also choose varieties that develop strong, dense roots. Recommended are:
- Storksbill
- Waldsteinie
- woman's coat
- Ysander
- Ivy
Especially with evergreen, woody species such as ivy and ysander, you can expect a solid fastening effect and also get a sturdy base for occasional walks on the slope to care for other plants.
Tip
To create a smooth transition from tall trees to ground cover, you can also plant low trees such as cotoneaster or creeping juniper in between.
Supplementary materials for slope reinforcement
There are countless ways to fortify a slope
Embankment mats
Embankment mats are used for the surface consolidation of embankments and pond bank slopes. They are therefore particularly suitable for fortifying slopes through planting. The mats are made of organic material (mainly coconut or jute fibers) and are woven as a coarse net. Through its mesh, plants can establish their roots and get support from the net structure until they have grown properly.
Some jute or coconut mats also have integrated pockets for plant balls, which allow larger and smaller plants to be firmly integrated into the slope design without slipping. The only disadvantage is the unchangeable position of the pockets, which limits your individual freedom of design.
For particularly steep slopes with problematic soil (those with rocks and boulders that are at risk of falling), a geogrid can also be useful. A geogrid is basically a net that secures the surface of sloping soil, but is made of solid plastics. This is why geogrids are primarily used in professional construction.
Plant baskets
It looks different, of course, with individual plant baskets, which are actually primarily intended for pond plants. You can also use these for greening flatter slopes and have freedom of positioning. However, they are of course a little more prone to slipping because they are not integrated into a coherent network.
Waterstones
Hydraulic stones are actually, as the name suggests, primarily used for watercourses, for example for the natural restoration of public bodies of water. The unprocessed pieces of rock usually consist of limestone or granite. They can also be used for dry slopes that are not too steeply sloped
Design ideas
Viewing areas on terraces
If you have a hillside property, you may live in an area that is generally hilly and hopefully scenic. Then it's worth turning the hills of your slope into oases for body and mind. An inviting place to sit and lie down on one of the leveled terrace areas, from which you can enjoy a wide view of the country, can provide relaxing and sensual hours. Especially if the slope faces south, the place should be covered by a shady tree or shrub or a parasol.
Raised bed(s)
If you terrace a slope with L-stones or wooden palisades, you automatically create a great foundation for an entire raised bed system. The comparatively low fastening elements bring the resulting terraces to an optimal, bend-free working height. This way you can use the slope profitably to enhance your garden in a practical and ornamental way.
The soil on the slope may of course need to be improved depending on the plants, which can be quite a lot of work. If the soil tends to be heavy and wet, drainage should also be considered. What's great about the terrace-like raised bed system is that different vegetation zones naturally arise, like a herb snail: in the upper areas, drought- and sun-loving plants can be cultivated, while in the lower areas, shade- and moisture-loving species can be cultivated.
Streams
If you have a natural slope in your garden, you can use it for streams
Slope situations in the garden are always ideal for babbling watercourses. They greatly enhance the garden idyll with the lively element. You can easily create a foil channel for a stream. Capillary barriers on the sides prevent plants from growing in.
Of course, the running water must run in a circle - this means that the water arriving at the bottom (perhaps in a pond) must reach the upper starting point (perhaps in the form of a spring stone or gargoyle) with sufficient pump power.
Frequently asked questions
Which economical solution is suitable for fixing slopes?
Unfortunately, safe, solid slope fastenings are not really cheap to produce. Of the options made from solid mineral material (gravity walls, prefabricated concrete modules or planting stones), planting stones are the cheapest option. Lightweight concrete plant stones in standard shapes are available from around 2 euros per piece. You can also save money with the planting stone method by doing a lot of your own work, as smaller models weighing around 15 kg per stone are relatively easy to process yourself. However, the concrete foundation with a gravel bed is expensive. A cheap, non-stone alternative are wooden palisades, which, however, have to be replaced every now and then because of their susceptibility to moisture.
How do you go about fixing a slope with planting stones?
The preparatory work for fortifying a slope with planting stones consists of creating a foundation. To do this, you need to dig a trench along the planned plant stone wall base (deeper depending on the desired wall height) and fill it with a gravel bed to protect against frost and a layer of concrete. While the concrete is still wet, place the bottom row of plant stones on top. The lowest planting stones should have a drainage layer of compacted gravel filled in the lower cavity. Potting soil can be added on top. Place the next rows of planting stones evenly, offset backwards, until the desired wall height is reached.
How complex is it to fortify a slope with a wall?
Gravity walls such as solid concrete walls, dry stone walls or gabions are the most complex and expensive variants of slope reinforcement. But they also offer a long-lasting, very reliable hold. The greatest planning and financial effort goes into creating a foundation, which consists of a frost-protecting gravel bed, drainage and a concrete base. Depending on whether you can/want to (partially) carry out these preparatory measures yourself or leave everything in professional hands, you will incur more or less high costs.
What should you consider when fortifying slopes with plants?
Fixing a slope with plants is the most natural and ecologically particularly valuable method. However, it is only suitable for slopes with a moderate inclination of a maximum of 7°. To secure the surface of the soil, incorporating mats made of coconut or jute fibers makes a lot of sense. A geogrid can also be used for difficult, stony soil. However, incorporating it into the soil is quite complex. A mixture of shallow and deep-rooted trees and ground cover for the gaps is suitable for planting.
