Build and design a rock garden – instructions and which stones?

Nobody creates a rock garden so easily in between. In contrast to the classic perennial bed, the focus here is on a material that – depending on the size of the area – weighs many tons. It therefore makes sense to approach the design and construction step-by-step. While in the classic perennial garden the plants are simply moved if they don’t like the look, heavy equipment is used in the rock garden if subsequent changes have to be made.

The planning

The size and nature of the available area marks the cornerstones of the planning. A slight slope is ideal, not only for the benefit of the visual effect. Rainwater and irrigation water drain away quickly here, which meets the needs of the plant world. A level surface can be processed with simple means, such as embankments. In addition, additional elements such as seating, decorations or small water landscapes should be included in the planning phase. The following aspects should therefore be included in the outline:

• The exact dimensions of the available space
• The light conditions in the different regions of the area
• The condition of the soil including any improvements
• The positioning of decorative elements
• The course of possible paths and paths

It is still too early to draw up a planting plan at this point. It is advisable to determine the types of plants only when the framework of the rock garden is more advanced.

Selection of the dominant stones

The rock garden primarily simulates a miniature alpine landscape. The overall design thus moves beyond formal garden design. Rather, it is the irregular arrangement of all the elements that creates the special magic. This goal is achieved primarily with the help of the stones, which thus play a central role in the selection of materials. In this respect, the hobby gardener is required to create a balance between the size of the area and the format of the stones. While mighty boulders are often integrated in a large garden, a boulder in a small area would kill the overall impression. Overall, a selection of divergent stone sizes is advisable, although within a uniform stone type.

If an irregular arrangement and different types of stones come together, chaos quickly arises instead of creative modelling. This circumstance applies in particular to the selection of the dominant stones within the garden. At least a similar type of stone is suitable for the gravel covering of the spaces and paths.

• Natural granite
• Alpendolomit
• Basalt
• sandstone
• diabas
• Jurakalkstein
• Gneis
• slate

First and foremost, it is the stones from the region that create a special naturalness in the rock garden. In addition, these are also advantageous from a financial point of view, since transport costs represent a significant cost factor in view of the high weight in the context of a purchase. In the nearby quarry you can usually even pick up the stones yourself.

preparatory work

In the first step of the construction work, the area will be processed in such a way that rock garden plants can then thrive. In addition to a sunny to semi-shady location, these require nutrient-poor, well-drained, sandy-gravelly soil. Basically, we recommend a drainage that prevents the formation of any waterlogging. In addition, you make the later care work much easier if a weed fleece is used. If a garden is regularly visited by voles, now is the right time to prevent them from accessing the rock garden with a vole wire. How to proceed:

• Excavate the surface 30-50 cm deep
• If necessary, incorporate a slight incline
• Remove all roots and weeds
• Lay out the vole wire without gaps
• Spread a 10-20 cm thick drainage layer of gravel, sand, rubble and soil
• Optionally create small mounds in some places
• Spread a weed fleece over it, the individual parts of which overlap at least 10 cm

The fleece not only has the task of suppressing weeds. At the same time, it reliably prevents the drainage from being clogged by the substrate that is now being applied. A 20-30 cm thick layer of sandy-gravelly topsoil or a suitable, commercially available potting soil is required.

arrange stones

Following the preparatory work, the most exhausting part is now when a rock garden is to be built and designed. Ideally, you have a planning sketch at hand. If a path through the garden is planned, this is laid out first. A path is made slip-resistant by first spreading a layer of fine-grained chippings and only then applying the decorative gravel. The next step is to distribute the stones according to size. This means that boulders are first arranged as eye-catchers, because they provide the structure. The medium to small specimens follow. This is followed by decorations such as benches or sculptures. The distribution of decorative gravel in the free spaces is only after the planting.

• Fix the larger stones to at least 1/3 in the ground
• For the particularly large chunks, the weed fleece is cut open in a cross shape
• Boulders receive additional stability in the drainage material

At this stage of the work, a break of several days is advisable so that the material can settle. Only then do you start planting the rock garden plants.

Suitable plants for the rock garden

Blue Fescue (Festuca cinerea) or Heron Feathergrass (Stipa pulcherrima) are ideal candidates. Blossoming perennials such as blue rue (Perovskia), highland asters (Aster ptarmicoides), alpine gentian (Gentiana alpina), junker lilies (Asphodeline lutea) or alpine toadflax (Linaria alpina) are responsible for striking splashes of color. They are all planted with a starter fertiliser, such as rock flour.

When all the plants are in the ground, it’s time for decorative gravel. In the last step, this is distributed on all exposed areas and between the plants at a height of approx. 8 cm.

Alpinarium – the stone highlight in the small garden

If the soil in the garden is loamy, nutrient-rich and moist, building an alpinarium is a sensible alternative to the classic rock garden. This is a modified structure of a nature park in the high mountains as a hill. In this case, the central premise is a sunny location. The mountain-like earth is artificially created within the framework of an adequate earth fill. You can get suitable material at a reasonable price in the form of a mixture of crushed stone, earth, gravel and rubble. With a mini excavator, which can be rented, you can raise the hill within a day.

• There is no need for additional drainage, thanks to the hill material, which is permeable anyway
• After the embankment, spread a weed fleece over the elevation
• Distribute a suitable, well drained, humus-rich substrate over it and press down well
• Distribute natural stones of different sizes over the hill
• Grout open spaces, like building a dry wall, for more stability

Plant a few plants in the spaces between the stones. We recommend edelweiss (Leontopodium), alpine bellflower (Campanula alpina), saxifrage (Saxifraga), snow heather (Erica carnea) and all houseleek species (Sempervivum). When assembling the plants, make sure there is a good mix of evergreen, deciduous and flowering species. In this way, the Alpinarium sets a striking accent throughout the year that no onlooker can resist.

Rock garden on the balcony

If there is no garden bed available, this does not mean that you have to do without a rock garden. Since alpine plants are used to being content with a small root space, the resourceful hobby gardener has the option of a rock garden on the balcony. Incidentally, this variant of planting is excellent for the beginner who still has to develop his green fingers.

manual

How to transform your balcony into an alpine dream landscape:

Magnificent natural stone troughs, decorative clay bowls or other stone vessels serve as mini beds. In any case, the planters should have a water drain in the bottom so that irrigation water does not cause waterlogging. Also consider the weight when making your selection. Even the most stable balcony can only withstand loads up to a certain limit. You have significantly more leeway in terms of load capacity if you want to create the rock garden on a terrace. Disused household containers can also be considered, provided they are made of hardy material. Have a look around the attic for wicker baskets or old jugs. Where there is no floor opening, one is simply drilled into it. Planting proceeds as follows:

• Cover the bottom of the vessel with a drainage of gravel, crushed potsherds or grit
• Spread a water- and air-permeable fleece over it so that crumbs of earth don’t clog the drainage
• Fill in a sandy-gritty substrate, such as a potting soil-sand mix with a little perlite or expanded clay
• Scatter small natural stones on top, decorated with thick pieces of root or small clay pots

Last but not least, the alpine plants have found their way into the mini rock garden on the balcony. The following selection from the wide range of suitable plants may serve as inspiration:

• Bergenie (Bergenia cordifolia)
• Brandkraut (Phlomis russeliana)
• Speedwell (Veronica teucrium)
• Fetthenne (Sedum telephium)
• Catnip (Nepeta faassenii)
• Schafgarbe (Achillea fillipendulina)
• Wolfsmilch (Euphorbia seguieriana)

If you have a sufficiently large pot, the rock garden on the balcony offers you the opportunity to kill two birds with one stone. A variety of popular kitchen herbs thrive wonderfully in the sandy rock garden climate. Thyme (Thymus serphyllum) also belongs to this group, as does mountain savory (Satureja montana). If space allows, sage (Salvia officinalis) and lavender (Lavandula angustifolia) can also be considered.

Conclusion
A rock garden transforms sunny, dry and barren slopes and garden areas into a miniature alpine landscape. With the right planning and instructions, even inexperienced hobby gardeners can build a rock garden themselves and design it according to their individual wishes. Since the stones play the leading role in this botanical spectacle, the right choice is of crucial importance for a good success. As long as they are natural stones of the same type, arranged in different sizes, nothing can go wrong. There is a breathtaking range of undemanding shrubs, perennials and grasses to choose from for planting. In the small garden, which also offers a loamy, nutrient-rich substrate in which rock garden plants do not thrive, the Alpinarium is available as an alternative.