Since the filling material of a conventional compost raised bed rots over the course of the gardening year - i.e. coarse materials first become compost and later fine compost soil - the bed loses an average of between 20 and 30 centimeters in height. As a result, the vegetables are then so deep in the bed box that not enough light and air can get to them. Timely refilling is usually advised.
The raised bed will sag over time and can be refilled
Is refilling really necessary?
The gardener should fill the sagging raised bed with fresh compost material in autumn so that the original level is reached again by spring. Some simply top up with fresh compost from the garden store or their own composter. In fact, this measure only makes sense for ergonomic reasons - i.e. for a comfortable working position on the raised bed. However, refilling is not strictly necessary for planting and the plants themselves - nutrients are still abundant in the compressed fill.
Refill raised beds - step-by-step instructions
If you want to refill your raised bed, you have two options. The easy way is to take ready-made compost and simply spread it over the bed as the top layer. However, the following method, which is carried out after clearing the bed in autumn, is more common:
- Use a rake to push aside the fine potting soil on the raised bed.
- Fill in compostable material as the underlying layer.
- Grass clippings, lawn sods (turn them over!), stable manure (especially horse manure) and coarse compost are particularly suitable.
- Spread the potting soil over it again and mulch the bed, for example with leaves.
The raised bed can rest until spring and then be replanted. So that it doesn't lose too much height over the growing season, you should mulch it regularly during the summer months - this way it practically fills up again by itself.
Alternative to refill
Instead of refilling the raised bed every year, you can simply let things take their course - and instead build the raised bed box in such a way that you can simply remove individual wooden slats, starting from the top, if necessary. In this way, you adjust the height of the raised bed to its fill level. The variant of simply placing two such raised bed boxes next to each other and using them alternately for planting and filling is particularly practical. One box is used as a compost bin for a year, while the other - filled - is planted. Finally, in the following year, they are exchanged.
tips
Regardless of whether you refill the raised bed regularly or not: every four to five years, the content has to be completely composted and you have to set it up from scratch.