As a rule, almost every raised bed has to be lined with foil to increase its lifespan. This applies above all to raised beds made of wood, because here the quickly decomposing material must not come into permanent contact with moisture. Raised stone beds also often need to be covered with foil, for example because freezing moisture attacks the masonry in winter. But which film should you choose for the raised bed?
Pond liner is often used for raised beds
pond liner
Pond liner is specially produced for the construction of garden ponds and is therefore not only very robust and waterproof, but often also UV-resistant. This property ensures the long durability of the film, because UV light makes the material porous. Pond liners also have the advantage that they must be as non-toxic as possible for stocking fish and plants - many types of fish in particular are extremely sensitive to toxins. And what doesn't harm fish should also be suitable for raised bed plants.
Stay away from PVC
This is why you use for lining raised beds - especially when it comes to raised vegetable beds! - If possible, no films made of PVC. These contain harmful plasticizers that migrate through the soil into vegetables and are suspected of causing cancer in humans. Therefore, when buying, pay attention to films that are free of these additives.
rubber sheet (EPDM sheet)
Durable EPDM foils are usually made from natural rubber and are characterized not only by extreme resilience and durability, but also by the fact that they do not emit any pollutants. For this reason, they are harmless to plants and other living beings (which nest in every raised bed) and are therefore environmentally neutral. However, they are also very expensive.
bubble wrap
This film is also known as drainage film for good reason and is intended to help prevent waterlogging. One side of this film is equipped with numerous knobs that drain excess water straight down from the raised bed. When buying, however, be sure to pay attention to the material: the cheap brands in particular are often made of unstable plastic and are mixed with plasticizers and other harmful substances.
tips
Instead of foil, you can protect your raised bed from moisture with other materials. For example, an old bathtub or zinc tub can be converted into a raised bed and attractively designed with a wooden or stone border, for example.