If you build a raised bed yourself, you should - if the bed box is made of wood or another moisture-sensitive material - protect it from penetrating moisture. This increases the lifespan of the raised bed. There are various methods of protecting a raised bed from moisture and rot.
The raised bed should be lined with foil
Fleece is water permeable
Above all, raised beds made of wood need good moisture protection, otherwise they will rot after just a few years and have to be replaced. It is important to protect the material above all from moisture from the soil and from the filling material. For this purpose, pond or dimpled foil is usually used, which is impermeable to water and thus offers reliable protection. Instead, using various nonwovens, such as those used in the garden, usually does not make sense. Fleece is often permeable to water and therefore cannot fulfill the hoped-for purpose - this applies in particular to weed fleece sold on rolls.
Protecting raised beds from moisture - what are the options?
In addition to waterproof fleece or foil, there are other ways to protect the sensitive material of a wooden raised bed from moisture. For example, you can build a raised bed out of natural or concrete stones and cover it with wood from the outside. Such a raised bed is particularly stable and durable, but also quite complex to produce and expensive.
Painting raised beds does not protect against moisture
On the other hand, special paints, varnishes or glazes with which the wood is treated are less suitable as protection against moisture. Such a protective paint is not sufficient on its own, further measures such as fleece or foil would have to be added. In addition, non-toxic paints should be chosen, especially if the finished raised bed will later be used to grow vegetables or fruit.
Weed protection fleece as a base for the raised bed - makes sense?
However, a fleece can not only be used to ward off moisture - as long as it is waterproof - it can also be positioned on the open ground of the raised bed in difficult locations in the form of a weed protection fleece and thus prevent stubborn root weeds from penetrating. In contrast to the moisture protection fleece, however, such a weed fleece must be water-permeable so that excess rainwater and irrigation water can drain off the raised bed.
tips
Plant bags made of fleece, which are easy to fill and plant and then fold up over the winter and can be easily stowed away, are particularly suitable for the balcony or terrace.