useful information
There is no legally valid definition for the term bark mulch. Since the legislature has not set any limit values for the proportion of foreign substances, the material does not have to consist exclusively of pieces of bark. In theory, it is allowed if bark mulch does not contain bark.
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seal of approval
When buying, look out for the RAL seal of approval, which was formulated by the Gütegemeinschaft Substrate für Pflanzen (GGS for short). Manufacturers undertake to continuously analyze their products. Since quality assurance is associated with additional costs, the price of the substrate increases. Therefore, low-cost providers refrain from such checks.
This is what the seal stands for:
- Bark mulch actually contains tree bark
- Specifications for grain size were met
- Product meets hygienic standards
This is where the quality differs
Since it is a natural product, differences in composition and appearance are not uniform. Fluctuations are normal to some extent. However, there are a few criteria you should check to get an indication of product quality.
composition
High quality bark mulch is characterized by purity. Filling materials are often contained in cheap products, since the costs can be effectively reduced by foreign substances. It is not uncommon to find shredded wood scraps, green compost, stones, plastic parts or broken glass in the packaging of discount suppliers.
Grit
The particle size must be within a specified range that is indicated on the packaging. This extends from 18 to 60 millimeters. Manufacturers of discount products do without work steps such as sieving in order to save costs. Therefore, the substrate is made up of coarse pieces of bark and fine material. Like dust, such fine particles increase the risk of waterlogging, so that adequate ventilation is not guaranteed.
Residues
While optical defects are easy to recognize, pollution and toxins can only be determined using laboratory methods. In addition to germs, which reduce the tolerance of the material for plants, the Tree bark Insecticide residues are located. This is more often the case with raw materials from abroad, because here pests such as the bark beetle are combated with non-degradable preparations.
Tips
The bark of trees sometimes contains high amounts of cadmium. In high-quality products from hardware stores and garden centers, the cadmium values of the products do not exceed the limit of 1.5 milligrams per kilogram of dry matter.
odor
Another sign of poor quality is a harsh or musty scent. This indicates that the bark mulch is older and is already subject to decomposition processes. Such aromas indicate suboptimal storage. A fresh substrate does not smell unpleasant or earthy, but pleasantly of forest.