A hillside property can undoubtedly be very attractive. In terms of use and processing, however, inclined positions present the owner with labour-intensive and often costly challenges. However, there are numerous different options that you can use for safe and attractive slope stabilization.

Gabions are often used to stabilize slopes

Table of Contents

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  1. the essentials in brief
  2. Principles of slope stabilization
  3. Possibilities for slope stabilization
  4. Additional materials for slope stabilization
  5. design ideas
  6. frequently asked Questions

    7. the essentials in brief

    • The steeper the slope, the stronger the attachment must be: From an incline of 7°, a concrete foundation must be set for a retaining wall
    • The options for slope stabilization range from greenery, gabions and wooden palisades to plant stones, concrete walls or dry stone walls
    • Planting on slopes has many advantages and the choice of plants is enormous

    Principles of slope stabilization

    Fixing a slope on the property is advisable for several reasons. On the one hand, the fortification secures the steep soil from gradually sliding down due to gravity and erosion. On the other hand, the steep area can also be used much better with 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 claims

    Inclination of the slope - necessary statics

    The steepness of the slope to be paved roughly determines which types of paving come into question. The steeper a slope is, the more structural devices it specifies for the necessary statics. For example, for a stable retaining wall on slopes with an incline of about 7° or more, concrete foundations must be erected and drainage installed at the bases facing the slope to drain rainwater and meltwater that flows down.

    orientation of the slope

    The orientation of the slope is more of an aspect that can be used to explore the options for use. A northern slope is perhaps only to be secured against slipping in a purely pragmatic manner, while on a southern or western slope it is worth considering combining the attachment with horticultural or recreational use. Depending on the desired utility value, it is also important to decide whether the solution should be cheap and simple or more expensive and labor-intensive.

    Personal style ideas and ecological claims

    Last but not least, your personal style preferences are important when choosing the type of attachment. Because such a slope reinforcement is something for the long term and should not break with the character of your existing garden. So decide on a variant that cannot become a thorn in your side.

    Also, listen to your inner self to find out which ideal direction you are taking with your garden tour in the future. Because no matter how ecologically valuable the solution will be, it will pay off in the long run.

    A slope reinforcement can be ecologically and optically valuable for the garden

    Possibilities for slope stabilization

    There are a number of ways to secure a slope. Here is an overview of the methods and their advantages and disadvantages:

    plant rings wooden palisades gabions drywall planting Prefabricated concrete elements
    benefits optically diplomatic, diverse planting possibilities simple, cheap, familiar look relatively uncomplicated, modern look romantic-authentic flair, diverse living space natural, ecologically most valuable (mostly) erectable without an excavator
    disadvantage relatively complex construction moderate holding power, prone to wet damage moderate stability, susceptible to rust, planning permission Challenging statics, possibly building permit only for flatter slopes, relatively time-consuming, high-maintenance Foundation, drainage & planning permission required

    plant rings

    Plant rings are a stylistically diplomatic and versatile option for slope stabilization. Due to the stone material, they offer a solid fastening effect, but can result in a very decorative and natural final picture when planted.

    The grooved rings or rectangular shapes made of lightweight concrete are staggered on top of each other on the slope like stairs. So that the whole thing remains stable and does not break away, a certain amount of preparatory work has to be done in the form of excavation and a concrete foundation. In addition, a drainage facility for rainwater and meltwater must be provided. A layer of gravel is laid on the slope surface, i.e. under the plant stones, for drainage purposes.

    The construction is relatively complex but worthwhile: because the plant rings can be made into an attractive design element with a variety of plants. A colourful, perhaps unusual combination of ornamental and useful plants is particularly recommended. Because in the many substrates that are close to each other but still separated from each other, this can be realized very well. If your hang isn't too far from the kitchen, the plant ring hang is also ideal as a living herb rack.

    Planting rings are a nice, simple slope stabilization option

    wooden palisades

    For slopes with a moderate incline, wooden palisades are a very attractive and comparatively inexpensive fastening option. They bring a warm, familiar character and are fairly easy to set up.

    The disadvantage of them is their moderate supporting power and their susceptibility to wet damage. For good stability and for water drainage, you should place the palisades one third deep in a trench bed filled with gravel and lean concrete. In order to prevent the palisades from rotting prematurely above the critical sinking section, you should also use pressure-treated variants made of robust types of wood such as fir, pine, oak or tropical wood. Nevertheless, one usually cannot avoid renewing the palisades after a few years.

    walls

    A slope can be secured particularly solidly with walls - but their construction also requires solid work. In order for them to fulfill their particularly supportive function and not become a hazard, they must be anchored in the ground so that they cannot tip over. This is especially true for gravity walls.

    gravity walls

    As its name suggests, a gravity wall is a weighty comrade. Walls made of masonry stones or solid concrete modules are called gravity walls. Gravity walls are a structural construction that requires a building permit in any case.

    With their large mass, gravity walls can also withstand difficult, particularly steep slopes with dense soil. So that it is not crushed by the slope and threatens to tip over, a gravity wall is sunk deep into the ground in a concrete foundation for at least a third of the total height. Concrete modules for erecting a gravity wall have a foot whose thickness also corresponds to about a third of the module height. They have a support wedge at the front edge, and they flatten out linearly at the front. As a result, they literally lean against the mass of the slope.

    Drainage is very important for solid walls that do not let water through. So that rainwater and snowmelt can drain off well, dig a second ditch behind the foundation ditch, which you fill 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 underlying properties or public spaces.

    A visually clean heavyweight wall with formwork blocks can be erected particularly easily and quickly. The hollow, rectangular concrete elements are usually made according to a simple system of joints with normal and corner stones or end stones and are simply filled with concrete on the inside to solidify them.

    gabions

    Gabions also hold back steep slopes safely

    Gabions actually also belong to the gravity walls, but we will treat them separately here because of their special style. With their linear, puristic look, gabions are currently very much in vogue. If you generally follow a very well-kept, tidy garden style, the walls loosely layered in metal frames are also ideal for slope stabilization. They are relatively easy to erect, but offer a little 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.

    Gabion walls need sufficiently deep ground anchoring in the form of a concrete foundation, especially when they are used to secure slopes. In addition, drainage is urgently needed. If, in winter, moisture accumulates on its lower back base and in the spaces between the stones and freezes, the wall threatens to topple over at some point due to the ice load. In order to prevent water from getting between the loose gabion stones and instead draining properly through the gravel bed, it is advisable to insert a strip of fleece at the back base of the masonry.

    drywall

    Dry stone walls are also heavyweight walls with a special character - therefore an extra word for them. With a dry stone wall or a construction made up of several terraced dry stone walls, you can create a natural, southern flair in the garden. Especially as a natural stone wall with uncut natural stones, such a building radiates an authentic, homely character. Depending on the stones you choose, you can conjure up a cottage garden style or a Mediterranean flair. In addition, a dry wall offers many ecological niches for a whole biotope of small fauna and spontaneous growth due to its unplastered joints.

    The erection of a dry wall on a small scale is definitely possible without any special expertise, but requires a little patience and a lot of love for design. Especially with natural stone walls. Because the uncut and therefore irregular natural stones have to be put together like a jigsaw puzzle to form the best possible fit that can withstand the forces of the slope mass and the weather. A dry stone wall over 1.20 m high was to have a concrete foundation. Static calculations are required for even higher constructions - here you should consult a specialist at the latest.

    Prefabricated concrete elements

    Prefabricated concrete modules mean palisades or concrete L-bricks. They are usually rather low and save a lot of mass compared to gravity walls thanks to angled base supports. Such concrete blocks are therefore more suitable for flatter slopes.

    However, the construction of slope supports with L-stones or concrete palisades does not really require less effort. Again, you need to pour a concrete foundation and set up drainage in the form of a gravel ditch. In most municipalities, a building permit must also be obtained for constructions with prefabricated concrete elements.

    planting

    Plants hold the earth firmly, preventing the slope from slipping

    You can also use plants as a natural variant of slope stabilization. Trees, shrubs and perennials also fasten the steepest slopes with their roots in the wild. In the garden, however, planting is only a good idea if there are moderate slopes of no more than 7°. For anything steeper, terraced areas with solid retaining walls are more recommended.

    The planting method has many advantages. On the one hand, you can make your slope attractive with trees and shrubs. On the other hand, they create more valuable habitat for the garden fauna.

    Shrubs and smaller trees with a well-branched root system are suitable for macro attachment. It is best to first create a rough "net" with gaps for the intermediate planting. Ideally, you should combine shallow and deep roots.

    Shrubs and trees that provide good soil stabilization and are decorative at the same time include the following:

    • liguster
    • Buddleia
    • cinquefoil
    • cornel
    • broom
    • shrub roses

    Groundcovers are ideal for micro-consolidation, 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 use varieties that develop strong, dense root systems. For example, we recommend:

    • cranesbill
    • Waldsteinia
    • lady's mantle
    • Ysander
    • ivy

    Especially with the evergreen, woody species such as ivy and ysander, you can expect a solid attachment effect and also get a sturdy base for occasional walks on the slope to care for the other plants.

    tips

    In order to create a smooth transition from tall trees to groundcover, you can also place low trees such as cotoneaster or creeping juniper in between.

    Additional materials for slope stabilization

    There are countless ways to secure a slope

    embankment mats

    Embankment mats are used for superficial reinforcement of embankments and pond bank slopes. They are therefore particularly suitable for slope stabilization through planting. The mats consist of organic material (mainly coconut or jute fibers) and are knotted as a coarse net. Plants can push their roots through its mesh and get support from the net structure until they are properly established.

    Some jute or coconut mats (€21.90) 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 restricts your individual freedom of design.

    A geogrid can also be useful for particularly steep slopes with problematic soil (those with rocks and boulders that are at risk of falling). A geogrid is basically a mesh that secures the surface of sloping ground, but it's made of solid plastics. That is why geogrids are mainly used in professional construction.

    plant baskets

    The situation is different with individual plant baskets, which are actually primarily intended for pond planting. You can also use such for the greening of flatter slopes and have free positioning freedom. However, they are of course more prone to slipping because they are not integrated into a coherent network.

    armourstones

    As the name suggests, armourstone is primarily used for watercourses, for example for the near-natural renaturation of public bodies of water. The unprocessed rocks mostly consist of limestone or granite. They can also be used on dry slopes that are not too steep

    design ideas

    Viewpoints on terraces

    If you have a hillside property, you may live in an area that is generally hilly and hopefully scenic as well. Then it's worth turning the heights of your slope into oases for body and soul. An inviting place to sit and lie down on one of the leveled terrace areas, from which there is a wide view of the country, can ensure hours of relaxation and indulgence for the senses. Especially if the slope is south-facing, the space should be covered by a shady tree or shrub or a parasol.

    raised bed(s)

    If you fasten a slope like a terrace with L-stones or wooden palisades, you automatically create a great basis for an entire raised bed system. Because the comparatively low fastening elements bring the resulting terraces to an optimal, bend-free working height. In this way, you can use the slope profitably for the functional and ornamental upgrading of your garden.

    Depending on the planting, the soil on the slope may have to be improved, which can be quite a lot of work. If the soil tends to be heavy and wet, drainage should also be considered. The great thing about the terraced raised bed is that, like a herb snail, there are naturally different vegetation zones: drought- and sun-loving plants can be cultivated in the upper areas, and shade- and moisture-loving species in the lower areas.

    streams

    If you have a natural slope in your garden, you can use this for streams

    Sloping situations in the garden are always ideal for rippling watercourses. They enhance the garden idyll enormously with the living element. You can easily create a foil channel for a watercourse. Capillary barriers on the sides prevent plants from growing in.

    Of course, the running water has to run in a circle - this means that the water arriving below (perhaps in a pond) has to be pumped back to the upper source (perhaps in the form of a spring stone or gargoyle) with sufficient pump power.

    frequently asked Questions

    What cheap solution is available for slope stabilization?

    Unfortunately, a safe, solid slope reinforcement is not really cheap to produce. Of the options made of solid mineral material (gravity walls, prefabricated concrete modules or plant stones), plant stones are the cheapest variant. Lightweight concrete plant stones in standard shapes are available from around 2 euros each. You can also save with the planting stone method by doing a good deal of your own work, because smaller models weighing around 15 kg per stone can be processed relatively easily by yourself. However, the concrete foundation with a gravel bed is expensive. A cheap, non-stone alternative are wooden palisades, which, however, have to be renewed from time to time because of their susceptibility to moisture.

    How do you go about fixing a slope with plant stones?

    The preparatory work for a slope reinforcement with plant stones is to create a foundation. To do this, you have to dig a trench along the planned base of the planting stone wall (deeper depending on the desired wall height) and fill it with a bed of gravel to protect against frost and a layer of concrete. Place the bottom row of planting stones on top while the concrete is still wet. The lowest planting stones should be filled with a drainage layer of compacted gravel in the lower cavity. Potting soil can come over it. Place the next rows of planting stones evenly offset backwards until the desired wall height is reached.#

    How complex is wall fortification?

    Heavy-duty walls such as solid concrete walls, dry walls or gabions are the most complex and expensive variants of slope reinforcement. But they also offer a permanent, very reliable hold. The greatest planning and financial effort is accounted for by the creation of a foundation, which consists of a frost-protecting gravel bed, drainage and a concrete base. Depending on whether you can/want to (partially) set up these preparatory measures yourself or leave everything in professional hands, you will also incur more or less high costs.

    What is there to consider when stabilizing a slope through planting?

    Fixing a slope with plants is the most natural and ecologically particularly valuable method. However, it is only suitable for slopes with a moderate incline of no more than 7°. The incorporation of mats made of coconut or jute fibers is very useful for securing the surface of the soil. A geogrid can also be used in difficult, stony soil. However, the incorporation into the soil is quite complex. A mixture of shallow and deep-rooted trees and shrubs and ground covers for the spaces in between is suitable for planting.

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