In order to create an optimal basis for the best growth in the raised bed, it is important to create layers. How to do this and what the layers should consist of is explained in the expert instructions.

Best time for raised bed stratification

Theoretically, a raised bed can be created at any time of the year. However, autumn offers the best moment. This is due to two factors: there is usually a lot of garden waste in autumn and the individual layers can settle sufficiently before planting in spring.

Layer Ground

A raised bed works in a similar way to a compost heap. It consists of organic substances that create humus and heat inside. The latter in particular is of great importance due to the rotting, because compared to a conventional garden bed, the higher temperature of around five degrees Celsius promotes growth and also accelerates the ripening of the harvest.

layer components

Before starting the layering, the necessary components should be available and ready. A distinction is made between raised beds with three and five layers.

  • Gravel or similar for drainage
  • coarse compost
  • Rotted compost
  • Garden soil with a fine structure
  • Five layers of additional finer garden waste such as chopped, leaves or lawn clippings
  • Five layers of additional air and water permeable material such as straw or turned sods

Other materials needed:

  • If necessary, spade to dig out a lawn under the planned raised bed
  • digging fork
  • Wire mesh, fine-meshed (rabbit wire works well)

tiPP: If the layering for the raised bed is planned for the fall, it makes sense to collect and compost garden waste from the spring and put the necessary tree and shrub cuttings in the fall so that there is enough material available.

Substrate as layer base

  • Ground should consist of normal soil
  • If there is grass at the site, cut it out (use sod later as a layer)
  • First layer should be on the ground
  • Roughly loosen the soil with a digging fork

TIP: Do not set it up on a solid, waterproof surface, such as concrete, stone slabs, plastic boards or wooden panels. This leads to waterlogging and the plants can quickly die off due to rot or become very susceptible to diseases and pest infestations.

floor grid

Before the raised bed is set up and the first layer is filled in, a fine-meshed wire mesh is to be considered layer 0. It serves to block access for voles. Here's how:

  • Lay out the wire mesh on the surface
  • Should be wider than the perimeter of the raised bed
  • Place raised bed on it
  • Cut corners, press up on the box and fasten (staple or nail)
  • Ideal: line the entire interior with rabbit wire (make sure the wire is the right size)

drainage layer

Installing a drainage system makes a lot of sense, especially if the soil is heavily compacted or stores a lot of water. This is placed directly on the grid at a height of about five to ten centimetres. In addition to gravel (pumice), the following materials are also suitable for this:

  • quartz sand
  • potsherds
  • expanded clay

TIP: About the drainage can mon lay a special "drainage fleece" that can be bought in any well-stocked garden store. It prevents the soil or parts of the individual layered components from being washed out during pouring.

Alternative:

Instead of the drainage materials mentioned, a layer of branches can also be used to prevent waterlogging. It should be noted that the branches will rot over time and the sinking of all raised bed layers can become significantly more extensive. If branches are used, their shape should be selected so that they form a relatively narrow "framework" so that the subsequent layer fillings do not simply trickle through. Branches are not a good alternative, but if no suitable material is available, they should be used.

Order of layers one to three

The fastest and easiest variant is the 3-layer system. Ideally, the raised bed should be filled with all three filling layers at the same height. Accordingly, a little calculation is required, in which the planned total height from the drainage to the surface of the earth is decisive. However, it should not be forgotten that a minimum height is required, but also a maximum height should not be exceeded in order to be able to benefit from the desired advantages of a raised bed. The following are the instructions on how the layering is optimally carried out:

1st layer: smaller filling
Similar to the 5-layer system, the first layer here consists of smaller components, which still allow air to pass through and ensure stability.

  • Suitable material: Leaves, grass clippings, coarsely chopped material, coarse compost
  • Minimum and maximum height: between 20 and 30 centimeters

2 layer: rotted compost
Rotted compost is then placed on the smaller filling material, which makes up the first “real” layer in the raised bed. It is important to ensure that it has rotted through thoroughly so that the actual rotting process does not lead to temperatures that are too high, which can damage the plants. There is the following to note:

  • Minimum and maximum height: 20 to 25 centimeters
  • Turn compost several times before stacking (allows heat to escape and loosens up)

3 layer: garden soil
Finally, garden soil is spread on the compost. It should have various properties, as described in detail under the heading "Sequence one to five - 5th layer: garden soil". If you plan to plant heavily consuming plants, you can also enrich the garden soil with some compost in order to ultimately achieve a higher nutrient content.

Order of layers one to five

Once all the preparations have been made and the drainage in the raised bed has been properly laid, you can start filling the various components in the following order.

1st layer: roughly chopped
The first "real" layer consists of a layer of coarsely chopped garden waste at least 20 centimeters high. This can be decayed tree bark or chopped branches. As part of the rotting process, it ensures that microorganisms are attracted and it is made easier for them to "climb" into the raised beds. No soil or other compacting material should be added here, otherwise the air permeability will decrease, which should also be too extensive for a closed compost mass to mix with the soil. In addition, coarsely chopped material is ideal for stabilization because it only sags slightly.

2 layer: air and water permeable material
The second layer is air and water permeable material such as straw or turf. The latter, however, are placed on top of the first layer with the turf facing upwards. The layer should always be the same height as a turf, regardless of the material used.

TIP: Very few have access to straw, although the next farmer would certainly give a little. If you don't have to dig a lawn, you don't have any turf. As an alternative, normal lawn clippings or bedding products for small animals can also be used.

3 layer: "fine" garden waste
Finer garden waste is used again. Lawn clippings and especially leaves are ideal components for the third layer of a raised bed. The following must be observed when filling the raised bed:

  • Lay loosely on the second layer
  • Reach at least 30 centimeters in height
  • Leaves should not be completely composted, but should already be dry
  • Distribute evenly into the corners
grass clippings

4th layer: compost
The penultimate layer is filled with compost. A coarse, slightly to moderately decomposed compost, which can consist of garden and kitchen waste, is ideal. At this layer height, the compost layer ensures warmth that reaches down to the roots of the plants, where it has a positive effect on them and provides many nutrients. The compost layer should be between ten and six inches high. Stratified too high, too high temperatures could develop, which damage the roots and at the same time cause an oversupply of nutrients, which can also result in intolerances in the later plants.

Alternative:

If compost is not available, it can be replaced with conventional garden soil if it is enriched to give it a high nutrient content. One of the following components is suitable for this:

  • 50 grams of horn shavings per square meter
  • 100 grams of calcium cyanamide per square meter
  • Stable Dung (moderately rotted)

5th layer: garden soil
The garden soil completes the filling of a raised bed. The following details should be taken into account:

  • 15 to 20 centimeters high
  • Use high-quality garden soil - inferior soil tends to compact and mold quickly
  • Should be nutrient-rich garden soil
  • Flower, green plant and vegetable soil are equally suitable

Further maintenance of the raised bed

subsidence of the strata

It is normal for the raised bed layers to drop over the next few weeks/months after planting. This is a sign that rotting is in full swing and in this way the volume inside is decreasing. This can be done simply by refilling with garden soil, as described above, to reach a "normal" height again.

Refill the raised bed

If the raised bed has been layered according to the instructions here, it takes about five years for the individual components to decompose completely, and with it the nutrient decline. This means that raised beds should be refilled every five or six years at the latest. To do this, the content is simply removed and, as described here, the layering is recreated. This is the only way to consistently benefit from the advantages of a raised bed.

waiting time before planting

Theoretically, a waiting time does not have to be observed for the replanting of a raised bed. However, the best time to fill the raised bed is fall, which means winter is just around the corner with freezing temperatures. Hardy plants and/or winter vegetables should be planted immediately after the layer filling. Incidentally, tulip bulbs are also a good idea for autumn/winter planting in the freshly created raised bed. Otherwise, you can simply wait until spring to plant them.

problem fresh stratification

The stratifications given here for the raised bed have the "problem" that they release a lot of nutrients. In the first year, only heavily consuming plants that can cope with the high nutrient content should be used. From the second year, medium-consuming plants are ideal and from the third year, weak consumers will find a suitable planting site in the raised bed.

Category:

Garden design