Raised stone beds have an almost unlimited lifespan. You can use all types of stones for this, although natural stones are often very expensive. A cheaper alternative are concrete blocks, which no longer have to look artificial.
What options are there for a concrete raised bed?
There are various options for a raised bed made of concrete: use of exposed concrete, concrete blocks, dry stone walls, mortared walls, lightweight construction systems or manhole rings. Concrete is inexpensive, versatile, durable, and lighter than natural stone, making it easier to work with.
Concrete blocks enable great diversity
Concrete is not only an inexpensive but also a very versatile material. You can use exposed concrete to build a raised bed, perhaps creating an interesting contrast to the naturally landscaped garden. However, there are also a whole range of concrete blocks that are based on natural stone. With their roughly hewn visible side, the broken edges and different colors in a natural look, such stones also look very pleasing in the natural garden.
Drystone and mortared walls
Another advantage of concrete - in addition to its price and variety - is its significantly lower weight compared to natural stone. This comes into play when building walls, for example if a raised bed is to be built on a slope. For high natural stone walls you need very large and heavy stones for static reasons alone. Accordingly, the edges of the bed are very thick, so that there is hardly any bed space left. You can also build both dry stone walls and mortar walls from concrete blocks, with mortar walls in particular being placed on a frost-free concrete foundation. The heavier the structure, the deeper and stronger the foundation must be built. In addition, an inner film is always recommended for mortared walls so that the mortar joints do not become porous and therefore flexible due to the constant moisture.
Concrete system blocks / lightweight construction systems
Easier to install are so-called system stones, which practically hook into each other thanks to grooves and thus create stable walls. Since these are hollow stones, you can build very high walls yourself thanks to their low weight. To make the hollow bricks heavier and therefore more stable against internal pressure, you can also fill them with gravel, gravel, grit or sand. The manufacturers always give instructions as to the wall height from which a mortar foundation or special adhesive must be used between the stones. If in doubt, ask a specialist for static calculations. If you want to build curved raised beds, you can use concrete blocks with a conical shape. These make it easy to build curves. As with dry stone walls made of natural stone, you can occasionally build wider joints so that they can be planted or used as shelter for small animals.
Inexpensive manhole rings
Parts of shaft pipes made from precast concrete can also serve as raised beds and have a practically unlimited lifespan. In addition, such raised beds can be set up quickly and easily - all you need to do is transport one or more manhole rings of the appropriate size to the desired location, fill them and plant them. However, you will need a machine to transport them - such as a small excavator - as they are very heavy and unwieldy. Smaller rings can also be rolled to the location by hand if you unload them vertically. The manhole rings are available from building materials dealers in many different sizes and with different diameters, although only rings up to around 150 centimeters are practical - up to this size you can just about reach the middle of the bed. Manhole rings can be placed on top of each other in the groove system so that you can build the raised bed at the desired height. Since they are impermeable to water, you don't need any foil.
Tip
Concrete slabs can also make a stable raised bed wall. For example, you can simply place high concrete paving slabs upright in a bed of dry mortar - and the raised bed is ready. Concrete palisades can be buried upright in the ground to form a stable bed frame.
