With a raised bed, you can experience the joys of gardening even in the smallest of spaces or in old age. This unique bed shape requires a special construction with several layers of soil, compost and green waste, which are available in a bucket higher than the actual ground as a vegetable garden or flower bed. The inner lining is important for the bed. This protects the planters, which are often made of wood, from moisture from the substrate.

Why foil?

The inner liner is an essential part of the raised bed as it protects the sensitive outer material from the constant moisture from the soil and compost. Above all, raised beds made of wood must be lined with foil on the inside, otherwise they will start to rot and have to be replaced after just a few years. On average, a wooden bucket lasts about five to ten years if it is not appropriately covered, which does not do justice to the great effort involved in building it. It's not just the wood that rots here:

  • high humidity of the earth hits the wood
  • heat is generated
  • Moisture moves into the wood
  • rotting is initiated due to the heat and humidity
  • Rot affects wood and bed contents
  • Bed contents rotted
  • Wood rots from the inside and decays
  • Fungal colonization is possible, which negatively affects plants

It is therefore important that you integrate the foils into the project in order to be able to protect and, above all, enjoy the bed over a long period of time. They ensure the longevity of the bed if you do not use materials that are waterproof and cannot rot.

Which inner linings for the raised bed?

Since the majority of all textiles and fabrics that humans can produce from nature also rot or become slightly damp, you have to rely on foils or fleeces made of rubber or plastics. This includes:

  • Pond liner made of different materials
  • bubble wrap
  • Fleece made of PET

You should definitely refrain from using classic PVC films, as they contain the largest amount of plasticizers that are harmful to plants, animals and humans. Due to the moisture, these quickly soak into the substrate and can literally "poison" crop plants in particular. For example, if you line your raised bed with PVC film and plant potatoes, the plasticizers can get into them and then damage your health. Therefore, when choosing a suitable raised bed foil, you should make sure that the foils used contain no or only harmless amounts of plasticizers.

Pond liner - the classic

The pond liner has been used for decades to create your own small bodies of water in the garden without them seeping into the ground. For this reason, pond liner is well suited for lining the raised bed. Even small raised beds can be lined with this fabric without requiring much work or skill. The biggest advantage of the pond liner is its high flexibility, because it was designed to hold water of different volumes without tearing. You can cover beds of different sizes with this film at a low cost, but here you have to pay attention to the different materials and compare them:

  • PVC
  • PE
  • liquid pond liner
  • EPDM

Notice: Never use regular plastic sheeting such as tarps that you can use to cover a vehicle. These not only have a negative effect on the growth of the plants, but also tear easily, shrink and often become leaky.

PVC

Most of the pond liners on offer are made of PVC, polyvinyl chloride. PVC is one of the most commonly used types of plastic and is mainly used for pipes because the polymer tolerates different heat effects well and is quite easy to manufacture. The advantages of PVC pond liners are:

  • smooth
  • elastic
  • can be easily relocated
  • easily adjusts to corners
  • extremely durable
  • resilient under heavy weight
  • can be easily repaired
  • available in numerous colors, but rather unimportant for the raised bed

In theory, such a film would be perfect for the raised bed. However, PVC films are extremely harmful to the environment and contain by far the largest amount of plasticizers compared to other plastic films. This makes them not ideal for use in a raised bed. They are also more susceptible to damage due to these plasticizers, since instead of water there are several layers of heavy, damp earth, compost and plant remains in the bucket. The PVC film often dissolves, leaving small holes through which the earth touches the wood. You should definitely refrain from using conventional PVC film.

PE

An alternative to classic PVC are foils made of PE, polyethylene. Polyethylene is also a thermoplastic material and can be used quite well as an inner lining for small raised beds because the material is quite stiff. He needs a little more time to undress, but the environmentally friendly value of the film should be mentioned. The plastic is biodegradable and leaves no residue. Although PE has a shorter lifespan than PVC, it does not emit any toxic vapors into the earth and can therefore be used without hesitation. Furthermore, the PE films are UV-resistant, which is not important for a raised bed.

EPDM

Films made of ethylene-propylene-diene rubber are the most expensive, but at the same time most durable variant. In contrast to PVC, EPDM films are more effective in many respects and are perfect as inner lining in raised beds:

  • organic certified
  • no evaporation, little plasticizer
  • tear resistant
  • stretchable up to 300 percent
  • high elasticity
  • tolerates temperatures down to -40°C
  • extremely durable
  • ozone resistant fabric

Due to its effectiveness, this foil can be used for several decades without being changed once, which makes it very advantageous for raised beds. Despite the small amount of plasticizers, they are not harmful for use in the bed. When lining, be sure to do this very carefully as raised beds are more difficult to line with EPDM liner than other pond liners. Due to the relatively small dimensions of raised beds, however, this is still easier than with large ponds or long streams.

liquid pond liner

The use of a liquid pond liner instead of a normal variant sounds quite modern. As the name already suggests, this is a liquid form of the otherwise layable pond liners and for this reason it is not laid over tracks. The liquid film is generously applied directly to the wood of the raised bed with a brush, roller or spray can and then left alone to dry. Then the different soil layers can be filled. The biggest advantage of them is that they are food safe, which makes them safe for use in a raised bed. Well-known manufacturers are Tripond and Impermax.

bubble wrap

Bubble wrap of any kind is perfect as an inner lining for a raised bed. This foil is easy to lay, contains no plasticizers and ensures effective drainage thanks to the nubs. Here the water can easily flow down without collecting between the foil and the wood. But these are not all the advantages of the bubble wrap:

  • resistant to chemical agents and wear
  • root resistant
  • impact resistant
  • tear resistant
  • pressure-resistant
  • easily withstands temperatures in the minus range
  • drinking water neutral

The numerous knobs on this film are particularly effective. It is attached with the nubs facing the wood, giving the raised bed effective air circulation and drainage. When using bubble wrap, you should also make sure that it was made of simple PVC. Although bubble wrap for the garden in particular is not provided with plasticizers, it can always happen that a manufacturer only uses PVC and no more environmentally friendly materials, which in turn can affect the quality of life of your plants.

PET fleece

The PET fleece is a fleece that was specially developed for use in the garden and is extremely effective against moisture in raised beds. The fleece consists of polyethylene terephthalate fibers (PET), which belong to the polyester family. Polyester is a popular fabric for modern, breathable clothing that can even be water-repellent. These properties are also transferred to the PET fleece. The fleece has the following properties:

  • can be easily cropped
  • works against pests
  • very easy
  • lets water through but not earth
  • frost resistant
  • weatherproof

The fleece cannot rot and is therefore perfect for use in raised beds. This gives you an easy-to-lay alternative to foil, which also has a particularly low weight. Another advantage is resistance to roots.

Materials for beds without foils

If you don't want to use foil, you can also use materials other than wood for your raised bed. There are not only numerous substances in nature that are waterproof, but also man has developed suitable materials, which are to be mentioned here. These include:

  • aluminum
  • stainless steel
  • Patina, corroded sheet steel, also known as Corten steel
  • stone
  • Plastics, but these can also contain plasticizers

These materials do not require foil as they are not themselves made of natural substances that could rot. A Mediterranean-style raised bed made of stones is just as enchanting as a modern accent made of stainless steel. They show no form of material fatigue and can easily be refilled every year when the soil layers of the bed have to be renewed. Such alternatives are particularly useful if you do not want to get additional foil and use it to line the beds. In addition, the following types of wood should be mentioned, which are particularly resistant to moisture:

  • teak
  • larch
  • douglas fir
  • azobe
  • Bankirai
  • Black Locust

These can also be used without foils, as they can withstand much longer than other types of wood despite possible rotting.

Category:

Garden design