Filling the raised bed: Tips for layering & filling

Raised beds are on the rise. After setting up, it's time to fill up. But putting on the different layers correctly is not easy.

Raised beds offer a number of other advantages in addition to being comfortable and back-friendly for gardening: They are difficult for snails reachable, they can also be found in places with less fertile soil vegetable growing enable and they make it easier for us to keep weeds at bay. Due to the heat that is generated when the filling material rots and due to the side exposure to the sun, harvesting in raised beds can be earlier and more productive. Success and yield are closely related to the contents of the raised bed and are therefore in your hands. We will show you what you need to consider when filling and refilling your raised bed and how you can avoid mistakes.

Filling the raised bed: the layers at a glance

Doesn't matter if that raised bed made of wood, stone or any other material, it should be made of different after filling Raised Bed Layers made of certain materials. In this way, the plant optimal growth conditions are created. The bottom layer (about 30 cm) serves as drainage so that water does not accumulate in the bed. Coarse materials such as branches and twigs, stones and wood chips are well suited for this. Existing cavities allow water to drain off better and offer soil organisms enough oxygen.
A further 20 to 30 cm of somewhat finer material such as leaves, grass clippings, turf, green kitchen waste or, if necessary, topsoil are then layered on top of this drainage layer. For example, if you balcony raised bed want to fill and do not have the materials described yourself, you can either ask garden owners about it or simply buy ready-made "filling material" for raised beds online.

The third layer is about 20 cm high. Depending on what materials are available, leaves, roughly decomposed compost, animal bedding, grass clippings, straw or similar can be stacked in thin layers. Mature compost can also be placed between the other materials for rapid decomposition and thus a more compact bed.
The finish is a layer of at least 20 cm thick consisting of a mixture of good topsoil, potting soil and mature compost. This layer of soil must not be too thin, so that the plant roots have enough space and nutrients.
The recommended heights of the layers must of course be adjusted depending on the size of the existing or planned raised bed.

Summary of shifts:

• 4 layers form a raised bed
• Lower layer ~30 cm: drainage layer made of coarse material (branches, stones etc.)
• Filling layer: 20-30 cm of leaves, grass clippings, kitchen waste
• Compost layer ~20 cm: Roughly decomposed compost, animal bedding, grass clippings alternately and in thin layers
• Planting layer ~20 cm: high-quality topsoil or commercial plant substrate

For the lower layers, you should already think about the intended use. Mediterranean herbs do not tolerate waterlogging and should be planted in a well-drained bed. The two lowest layers should therefore be composed of many coarse and poorly or non-decomposable materials such as larger branches or stones, coarse crushed stone or gravel. With a planned, perennial planting of the bed (e.g. with flowering perennials), it is not as easy to fix the sinking of the filling material as when using it as a vegetable bed. Therefore, the bottom layer should not contain any degradable matter, but only inorganic materials such as coarse crushed stone, gravel or stones. A gardener's fleece is then placed on this layer, which prevents the soil of the upper layer from being washed away with the irrigation or rainwater. Even with very high raised beds (from 80 cm), for the vegetable growing planned, this procedure can be recommended. Proceed in the same way for the following layers as already described.

TIP: Separate each layer with fleece to prevent the soil from being washed through the coarser layers when watering or raining.

Filling the raised bed: instructions

A raised bed should at best be filled in autumn, otherwise in early spring. This leaves enough time for the bed contents to decompose and sink before the first planting. If the bed surface sags during the growing season, the plants practically “collapse”. Some plants like potatoes or Kohlrabi have no problem with being simply piled back up with soil afterwards. But other plants like this less. Filling in autumn has another advantage: the raised bed can be used as a kind of composter. The lower layers can be collected from all sorts of garden waste during the winter months. Pet-free kitchen scraps and moderate amounts of pet bedding can be placed in the raised bed for months. With the mineral decomposition that begins immediately and with the help of many small creatures, the bed can swallow incredible amounts of organic matter. In this way, valuable, nutrient-rich material accumulates inside the bed, which is made available to the plants through decomposition over time. With kitchen waste, however, care should be taken to ensure that no highly salty foods get into the bed, because most plants do not tolerate salty soil well.

• Fall is the best time to plant a raised bed
• Organic components can already be decomposed over the winter
• First sinking of the filling material before planting, so that it can still be refilled without any problems
• In autumn, the raised bed can be used as a kind of “compost bin” for garden waste

Before filling, you should think about lining the raised bed. In the case of wooden raised beds, pond or knobbed foil can extend the durability of the wood. Likewise, with some types of bed borders, such as raised beds made of Euro pallets, the lateral escape of soil and water can be prevented by a film. When choosing the film, it is important to ensure that it does not contain any plasticizers. It can be attached to the sides of the bed using a tacker, for example. With dimpled foil, the dimpled side should be on the wood so that the wood remains "ventilated". Of course, the bottom of the raised bed remains free of foil, after all, water must be able to escape from the bed.

• Raised bed walls made of wood? Line the walls with foil or bubble wrap
• Bubble wrap allows wood to breathe inside (due to air spaces between the upholstery)
• Do not line the bottom so that excess water can escape downwards

Filling itself is not a big deal. Layer by layer, first coarse and then finer material is placed in the bed. If the bed has not yet been built, you can start filling before the border of the bed is finished. Because the filling material does not have to be lifted over the raised bed wall and is easier to do by hand. In any case, make sure that the lower layers are not too low. Otherwise, much more expensive potting soil and compost will be needed in the end than is actually necessary. In order to avoid that the lower layers become too thin or sink immediately with the first precipitation, the filling materials should be moist be: not wet, but well moistened, because in this way the material settles evenly and the height of the layers can be better judged will. In autumn, most of the garden leftovers are usually moist enough. If not, each filling layer can be sprayed over briefly with a watering can.

• Filling while building the raised bed makes work easier
• It is better to have lower layers that are a bit more generous and thick than the upper layers – this is easy on the wallet
• Use moist filling materials, this reduces sagging from the start

If the bed is filled in autumn or winter, check in the spring whether the filling has dropped and, if necessary, top up the plant substrate again. If the filling takes place shortly before planting, you should definitely wait for a few rain falls or pour them vigorously several times. This way the filling material will eventually sink a bit and you can top up the soil and compost in good time before planting or sowing.

Expert tips for filling: Avoid mistakes

There is virtually no way to prevent the organic fill material in a raised bed from shrinking over time. The warm, humid environment of the raised bed leads to rapid rotting and very fertile soil. But rotting is always associated with a loss of organic material, which is why the bed surface naturally settles over time. Especially if you only fill the bed in spring, you should consider the following measures to avoid a failed harvest due to a shrinking raised bed:

1. Pile up soil afterwards
   When choosing plants that tolerate a subsequent accumulation of soil, such as Potatoes, tomatoes or kohlrabi can easily be soil if the soil surface sinks be refilled.
2. Grow early-ripening vegetables and stock up after harvest
   When deciding on an early spring vegetable, the bed can simply be refilled with plant substrate after harvesting. Spinach, lettuce or radishes ripen quickly and can then be harvested completely. The bed is refilled and then planted with pumpkins, celery or courgettes, for example, which then remain in the bed until autumn.
3. Select non- or poorly-decomposable materials
   As a last alternative, the bed, just like a raised bed for herbs, can be filled with good drainage, i.e. a lot of inorganic, non-decomposable material. If the bottom two layers consist of more stones, coarse crushed stone, grit, sand, gravel and expanded clay, these and consequently the entire bed will settle less. However, with this alternative it should be borne in mind that this material does not produce a fruitful and nutrient-rich soil can be formed, as is the case with conventional stratification of the fill material happens. Plants that consume a lot, such as courgettes, pumpkins or cabbage, quickly reach their limits with their nutrient requirements.

If you already have problems with a bed that is settling during the growing season, you will have a continuous one Topping up small amounts of soil works better than adding a plant-suffocating large amount of soil or soil amount of compost.

tip: Before you fill the raised bed, you should first find the right one raised bed location determine. We will help you to choose the right location.

Do you want to create a raised bed in your garden? In our article we will show you how to create one Create a raised bed in 10 minutes can.

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