Building a raised bed out of wood, stone or concrete – construction instructions

There are really a number of good reasons for this:

• Gardening becomes more relaxed, even for people who have “backs”
• For the elderly, the raised bed is often the only way to grow vegetables
• The vegetables like the raised bed because the sun warms them up early at the beginning of the season
• around correctly filled raised beds, the earth is warmer all year round
• So tomatoes and other southerners can grow very well there
• Or local vegetables in crop rotation, the season in the raised bed is longer
• The correctly filled raised bed is a “humus factory”

The fact that a raised bed expands the garden area is unfortunately a misconception with normal raised beds: Two square meters down on the ground is also two square meters one floor higher – however, you will find out below how you can undo this physical law.

There are enough arguments, however, and there are also a few for building a raised bed yourself:

When and why building yourself is worthwhile

Raised beds are offered in garden centers and at the beginning of the season also at discounters in many kit variations.

The purchase of such a kit is recommended in various cases: You simply want a raised bed, without any extraordinary demands on the design, please do it quickly, and your DIY ambition is just as clear as your DIY skills.

But: A kit that really creates a raised bed and not a flower pot replacement without real raised bed qualities costs a lot. The more affordable variants from 100, – € are made of plastic, which is usually not visible in the picture on offer, wooden kits for this price result in tiny raised beds. The kit for a “real” raised bed made of larch wood costs between € 250 and € 700, has a (often too low) standard height and a size that is not always optimal for the planned location.

If you build your raised bed yourself, you can determine exactly the right size and depth, and any shape, up to a rhombus or a triangle. Larch wood in 19 mm thickness costs around € 17 per square meter, then you still need a few posts and joist hangers, you can build the raised bed in the size of € 250 for less than € 50, and you can even do the with your orthopedic surgeon Determine the most back-friendly height for your height.

Raised bed made of wood

The wooden raised bed for ambitious hobby do-it-yourselfers is planned correctly at the desk, and it is built according to correct construction instructions.

We cannot do the planning for you, it should be tailored to your personal needs; an overview of the assembly instructions follows:

• At the beginning there is the choice of material, the larch just mentioned is well suited
• Larch wood is popular because it has a long shelf life outside
• It does not have to be Siberian larch wood (when it is dismantled, old forests are exterminated)
• Local larch wood is sufficiently available and sufficiently rot-proof
• Spruce and pine rot faster, but they are unbeatably cheap
• You need beams at the height of the raised bed, one post for every 80 cm / 1 m
• Metal joist hangers are attached to the lower end of the posts
• Use wood and posts to build a square or rectangle of the size you want
• The length can be determined depending on the space and the desired cultivation area
• How comfortably you can work your raised bed depends on the depth
• A depth between 1 m and 1.20 m allows easy access from both sides
• If the raised bed is only accessible from one side, it should remain narrower
• Posts with joist hangers do not have to be embedded in the ground, the frame is simply set up
• Before the construct comes into place, a root protection film can be placed underneath
• This is particularly important if there are roots lurking nearby that grow into the raised bed from below

You do not necessarily have to line the raised bed with foil, you would have to check that it is free from harmful substances, and it is only there to protect the wooden walls from rotting due to moisture. If you use the right wood and protect it against moisture by painting it with linseed oil, you do not need a foil.

The fast wooden raised bed

Perhaps you still have scrap wood standing around that you can assemble with a little addition to the raised bed frame. This is not only an inexpensive, but also a relaxed solution – if the wood is really left over, you don’t have to worry about durability at all. You just build your raised bed, and it can show signs of age at some point, the better it fits in a natural garden. If you build with wood more often, you will always have to repair wood.

Another possibility is to equip the frame of the raised bed with a wicker wall made of willow twigs, if at some point it becomes brittle, the next wicker wall is placed in front of it …

Raised bed made of stone

Built to last, a raised bed looks good if you wall it out of stone or pour it out of concrete.

Here’s how you could build a stone raised bed:

• Define and mark the base area (do not forget the thickness of the stones)
• Decide whether a foundation should be poured, if necessary pour it
• The foundation may only be under the walls, the floor in the raised bed must remain permeable to water
• Walls z. B. from sand-lime brick, preferably with ready-mixed mortar

Concrete raised bed

A variant with a timeless style is the raised bed made of poured concrete, which goes particularly well with many modern buildings. This option is often used when very special architecture is to be accompanied by equally special architecture on a small scale. Then very imaginative formwork can be created, sometimes with artists. There are no general building instructions for a raised bed made of poured concrete, it will always be your own design, for which you have to obtain or build the appropriate formwork beforehand.

Here are the basic instructions for building concrete formwork for different shapes:

• Anything that does not absorb and can be treated with a release agent is suitable as a material.
• Wooden formwork panels, coated shelves, PVC, Plexiglas, Styrofoam, Styrodur, etc.
• Metal is usually not suitable. B. react with the wet concrete
• Other metal plate remnants would have to have a special coating
• If you have a metal plate left in the house / garden environment, this is almost never the case
• The material has to withstand considerable pressure, concrete mass has a gross density of 2,400 kg / m3
• The higher the formwork, the higher the pressure, regardless of the width (volume)
• Then the formwork must be supported by tensioning straps and / or firmly screwed wooden supports
• Formwork elements are best connected by screws and not nails
• This is because screws can be removed much more easily than nails when stripping the formwork
• The formwork is treated with release agent so that the concrete can be easily removed from the formwork
• Formwork oil, paraffin, silicone spray, petroleum jelly and other substances that make the surface of the formwork smooth are suitable release agents
• You can combine all kinds of things, but you should first water a small flower pot with unknown material combinations

Further information:

• If you design very creative formwork forms, always make sure that the hardened concrete can be “pulled out” afterwards
• If your design contains small corners, they need reinforcement, otherwise there will be shrinkage cracks
• Such reinforcement can, for. B. made of “crumpled” wire mesh
• When buying, ask whether the wire mesh is compatible with concrete
• Calculate beforehand how much concrete you will need
• If the volume is difficult to calculate with creative shapes, you can use tricks:
• Build yourself a solid cardboard cube measuring 10 x 10 x 10 cm (or many for exotic shapes)
• You then have cubic decimeter cubes, 10 each in depth, width and height make 1 cubic meter
• Now mix the calculated amount of concrete all at once (+ a little more)
• When the concrete is compacted or compacted itself, it penetrates into cracks of 0.1 mm
• The formwork would then have to be worked so precisely
• If you don’t feel like doing this, you can seal the cracks with sealing tape or putty
• After pouring, the concrete has to dry for about 12 hours, then it is carefully stripped out
• The concrete is not yet very firm, corners, edges, etc. must be treated like raw eggs
• It is switched off so that the concrete can dry out – but not from the outside in
• “Drying” is the wrong term, concrete becomes solid through reaction with the water
• The same amount of water must be available throughout the entire concrete body
• So surface evaporation is prevented by watering or covering
• Covering (with plastic sheeting) is more convenient, watering could wash away concrete

There is also a very simple way to get a raised bed made of concrete: You stack it up from concrete blocks, from concrete blocks in the desired size, which is available in many different designs.

But more garden space

There is a possibility how you can get “more garden space” with the raised bed:

You build your raised bed out of concrete plant stones, which can be stacked in a staggered manner, so that several planting areas “look out” in each row of walls. With quite a large volume of earth behind it, a lot can grow.

If the raised bed is fully accessible, you can easily accommodate an entire herb garden outside the raised bed … or the annual harvest of Jiaogulan leaves, or the daily salad portion, or you can transform your raised bed into a blooming eye-catcher with various climbing flowers.

Active soil life in the raised bed, healthy growth for the plants

When the self-built raised bed is finished, it should develop an active and healthy soil life for the plants and last as long as possible. You can influence this by filling it carefully:

• A layer of gravel is placed on the ground as drainage so that moisture never accumulates
• If you have voles around, you can use a close-meshed wire mesh as the next layer
• The raised bed is not simply filled with soil, but with up to 6 layers of organic material
• This filling depicts “real earth” in its formation
• A layer of roughly chopped wood is poured in at the bottom
• This is followed by a layer of snippets, untreated paper or cardboard or finely chopped wood
• This is followed by plant residues, leaves and semi-ripe compost
• Finally, there is the layer for the plants, ripe compost and humic soil
• A correct layer structure turns the raised bed into a raised bed in the true sense, namely with a floor temperature of up to 8 ° C
• A decomposition process takes place in the lower layers, releasing heat and nutrients
• The height of the layers should be about the same thickness, and the structure is of course not “set in stone”
• But the less you stick to it, the higher the risk that nothing will happen in your raised bed
• The bed sags over time, then it is filled with compost and garden soil
• After 5 or 6 years the lower layers will have rotted away and the bed will be rebuilt
• The content of the raised bed that has become humus can be distributed in the garden

The correct construction of a raised bed is especially worthwhile in gardens where there is only a thin layer of mother earth over a large amount of sand, which becomes a little thicker each time the raised bed is emptied.

Bottom line : A raised bed can be built in many different ways and in many different designs. A garden without a raised bed can also be a great garden, but a raised bed brings a lot to the passionate gardener. When things are filled, emptied and re-layered in autumn, the raised bed also absorbs leaves and clippings and at some point turns them into humus – a noticeable and useful help with gardening