The extraction of peat for plant soils is an intervention in nature. It releases carbon dioxide and thus damages the climate. In the meantime, there are alternatives: peat-free substrates that are particularly well suited for potted plants. However, these peat-free soils have very different properties than peat soil: they store nutrients and water less consistently. Therefore, the care of plants growing in peat-free soil must be adapted.
Anyone who wants to garden in harmony with nature should – if possible – use peat-free soils.
There is now a wide range of peat-free or peat-reduced planting substrates. They can be used for a wide variety of purposes in the garden: as sowing soil, for potted plants or for filling raised beds. Plants can thrive well in peat-free soils. This has also been demonstrated by test plantings at Egapark Erfurt. There, tubs were planted with conventional garden soil (citrus substrate), while other tub plants grow in peat-free substrates. “In principle, the plants also thrive well in the peat-free soils, they grow into strong plants and bloom lushly,” says master gardener Jürgen Meister, who looks after the tub plants. Nevertheless, peat-free soil requires more care. The very loose substrate cannot store water and nutrients as well. The substrates dry out more quickly and need to be watered and fertilized more frequently.
Tips for buying: “peat-reduced” is not “peat-free”.
If you want to use good peat-free substrates, you should look for the RAL seal of quality and the designation “peat-free”. Peat-reduced” or “low peat” soil still contains a certain amount of peat. A closer look is also required for organic soil, because it does not have to be 100 percent peat-free. Organic soils are not automatically “peat-free”.
Properties of peat-free soils: Storage properties and nutrient content
Peat-free soils can have very different properties, depending on their composition: The nutrient content, pH and also the storage capacity depend on what the substrate is made of.
Peat-free soils have a loose, airy structure due to various ingredients such as wood fibers, coconut pulp and expanded shale, and the soil is well aerated. The disadvantage: water and nutrients pass through more quickly and are not stored well. The substrates can dry out more quickly. The properties of the substrates can vary greatly. If the percentage of retentive materials such as wood fiber and brick chips is high, the substrate retains water and nutrients better. Meanwhile, peat-free soil is offered, which is quite specifically tailored to the needs of different plant species. So you’d better reach for these special soils.
Peat has been formed over centuries in bogs. The basic material for many soils is, so to speak, finished and no longer changes through decomposition. Peat-free substrates are different – they change. Carbon rich wood fibers decompose and remove nitrogen from the substrate. Therefore, the nutrient depot must be replenished regularly, especially with nitrogenous fertilizers.
Peat-free soils are more susceptible to pests: therefore, the substrates should be used fresh and not stored for a long time.
Watering and fertilizing: Adapt care with peat-free soil
It is better to water more often, but in small amounts.
Tubs and balcony boxes with water reservoirs and water level indicators are useful. The plants can then draw on the collected reserves and the gardener can see when water is needed.
Peat-free substrates need to be fertilized again more quickly. Especially if there are a lot of woody parts, nitrogen is used up and needs to be replenished. Organic nitrogen fertilizers such as horn shavings help here. The regular application of liquid fertilizers is also advisable, as this is immediately available to the plants.
What is peat?
In oxygen-poor, waterlogged bogs, nutrient-poor, acidic peat is formed from dead moss and other plants. According to NABU, it takes 1,000 years for a layer of peat one meter thick to form. In order to cut peat, the bogs usually have to be drained – the peat mosses then stop growing. Carbon dioxide is released during the decomposition process. Conservationists therefore criticize the extraction of peat as environmental destruction.
In Germany, peat is mined mainly in northern Germany. It is used for fuel, and only a small part of it (four percent) is processed into plant soil. According to NABU, the majority of peat is mined in the Baltic States and imported. Here, peat extraction is actually increasing – contrary to the trend – with serious implications for climate change.
What is the difference between peat soil and peat-free soil?
Peat soil: Peat has matured over centuries and – when mined – has constant properties that hardly change: It is low in nutrients and has an acidic pH. As a basic building block for garden soils, its ingredients are therefore well-defined, making it an ideal starting material for potting soils. Enriched with clay, fertilizer and other additives, peat becomes peat soil. It can be precisely adapted to the different requirements of various plant species. In addition, the soils are structurally stable and give the plant roots a secure hold over a long period of time.
Peat-free soil is different, it transforms in the course of a season. Peat-free soils are mixed together from completely different organic materials, such as green waste compost, wood or coconut fiber.
These ingredients change over the course of the garden year. Microorganisms work and decompose the material. (In the case of peat, this process is complete.) Bacteria consume nitrogen as they mineralize compost and wood. However, because the ingredients of the parent material are not precisely known, it always remains uncertain what ingredients the peat-free soils will still contain as the season progresses.
Thus, it is not clear what the plants need. In the meantime, there are good substrates that are almost equal to conventional potting soils in their positive properties. Research and work is being done to develop peat-free soils that can also be used by commercial gardeners who rely on a high reliable yield. In the hobby sector, there are now many substrates for potted plants that are good alternatives. However, the care of the plants must be adapted.