How to fill a raised bed: Instructions & tips

Building and filling raised beds

A raised bed offers a number of advantages and is a good start to gardening, especially for beginners. With a raised bed, you can create a bed anywhere and also grow and harvest your own vegetables on the balcony or in the city. You can read about what you need to consider when building a raised bed here.

Before you start filling, you should line the inside of your raised bed with foil. This is particularly important for wooden raised beds to protect the wood from rotting. A vole grid should also be placed at the bottom. The small rodents feel particularly at home in raised beds and like to nest in them.

Once the basic structure for your raised bed is in place, it's time to fill it. Here it is important that you work in layers. Here is an overview of the layers in a raised bed:

Filling raised beds - layers at a glance

• Drainage layer 1: 20 to 30 cm/ 7,8 to 11,8 in of coarse wood cuttings (branch and shrub waste that does not release toxins)
• Drainage layer 2: 15 to 20 cm/ 5,9 to 7,8 in in of shredded material (fine prunings or chaff)
• Transition layer: 10 to 15 cm/ 3,9 to 5,9 in of grass clippings and leaves
• Nutrient layer: 20 cm/ 7,8 in in coarse compost (less decomposed)
• Planting layer: 30 cm/ 11,8 in of soil mixed with well-decomposed compost

Instructions: how to fill a raised bed correctly

• Vole mesh & foil: Before you fill your raised bed, you should lay out the wire mesh just discussed. You should also line the inside of your raised bed with foil.
• Drainage layer: As we mentioned above, it makes sense to first fill in a loose layer that ensures good drainage and aeration. For example, twigs and branches from pruned fruit trees, pieces of wood or wood chips are suitable for this. The material also serves as food for soil organisms and will gradually decompose.
• Organic material and raw compost: Next, you can place garden waste such as grass cuttings and leaves. Similar to your compost heap, they will decompose together with the woody components of the drainage layer. This layer therefore provides a nutrient reservoir for your vegetable plants. You can also spread slightly rotted raw compost on top of the layer of garden waste. Be generous with this, so your raised bed will have enough nutrients for years and you will hardly need to fertilize it.

• Ripe compost and topsoil/garden soil: Next, you can alternate between mature compost and soil. You can either use organic garden soil from the DIY store or buy a trailer load of humus or topsoil from a builders' merchant. The second option is usually cheaper, but also much more time-consuming.
• Top layer: A loose, nutrient-poor substrate, such as potting compost or special raised bed cover soil, is recommended as a top layer. Your plants can germinate well here, but are not immediately spoiled with nutrients. This stimulates root formation and ensures that your plants penetrate into the deeper, nutrient-rich layers. They are also better supplied with water there.
• Optional mulch layer: Last but not least, you can also add a layer of mulch to your raised bed to protect the soil from drying out. This is because water is a weak point of raised beds: Due to the elevation and faster heating, a raised bed dries out much faster than a conventional bed. A mulch layer of weed-free grass clippings, leaves or straw ensures that the soil underneath stays moist for longer.

Filling the raised bed on the balcony

In a raised bed, it is particularly important to work with a drainage layer to avoid waterlogging. Waterlogging can lead to root rot and make your raised bed plants sick. A drainage layer is particularly important in raised beds on the balcony, as these raised beds are usually closed at the bottom and lined with foil. This means that the water cannot run out at the bottom and inevitably builds up. However, it is also important to install a drainage layer for raised beds that are open at the bottom. In this case, however, the layer can be a little thinner, as the water can drain into the soil. You can also leave out the vole grid for raised beds on the balcony. As they are closed at the bottom anyway, the small rodents cannot get into the bed.

Filling wooden raised beds - pay attention to the weight of the soil!

Another point is the filling of large wooden raised beds. If you fill your raised bed with soil, this will weigh quite a lot in large beds. If the soil fills up with water, it can become so heavy that it pushes the wooden frame of your raised bed apart. To avoid this, it is a good idea to reinforce the frame with a threaded rod. This will keep your raised bed in shape and prevent the frame from breaking apart.

Long-term raised bed maintenance: how to do it

The lower layers of your raised bed consist of intact and slightly rotted material. This organic material is decomposed by soil organisms over time. This is why the soil in the raised bed settles over time and looks as if it is becoming less. This can also happen a few days after filling, when cavities created during filling collapse. So don't be surprised if your raised bed looks much less full after a while - this is completely normal.

After the first or second season, however, it makes sense to replace the bottom layers. This may seem a little time-consuming, but it only needs to be done once every 1 - 2 years. To do this, you can shovel some of the soil out of the raised bed and temporarily move the rest to one side of the bed. Then fill the free half with wood scraps, green cuttings and raw compost. Now push the top layers to the other side over the material you have just filled in and fill in the other half at the bottom. Then you can fill in the rest of the soil and you're ready to go again.

Planting raised beds: Tips and ideas

Once your raised bed is filled, it's time for the final step: planting your raised bed. To bring as much biodiversity as possible into your raised bed and thus increase its ecological value, you should grow your raised bed in a mixed culture. In addition to vegetables, you can also grow flowers and herbs, which provide food and a habitat for insects, especially in the city.

We have already created planting plans for a whole garden year in a raised bed. You can also find ideas and inspiration for a planting plan for the first year, when the soil is still very rich in nutrients. All of these planting plans show you mixed crops that are great for planting in your raised bed. We wish you lots of fun and a successful harvest!

Mixed crop planting plan for raised beds

For inspiration, we have prepared some bed plans for your raised bed. With mixed cultivation, you can make the most of the little space you have.

If you have any questions or comments, please write to us at [email protected]. Would you like to receive helpful gardening tips all year round and plan your own beds optimally? Then register here or download the Fryd app for Android or iOS.

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Cover picture by congerdesign on Pixabay