Bark mulch has many benefits and is very popular among gardeners. Depending on the season, not only hardware stores and garden centers but also discounters offer different products in different price ranges. With temptingly cheap offers, however, you should pay attention to a few aspects.
Mulch is available in different grain sizes, colors and qualities
useful information
There is no legally valid definition for the term bark mulch. Since the legislator has not specified 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 any bark.
seal of approval
When buying, look for the RAL seal of quality, which was formulated by the Quality Association for Substrates for Plants (GGS for short). Manufacturers undertake that their products will be analyzed on an ongoing basis. Since quality assurance involves additional costs, the price of the substrate increases. Therefore, low-cost providers refrain from such reviews.
This is what the seal stands for:
- Bark mulch actually contains tree bark
- Specifications for grit were met
- Product meets hygienic standards
Here the quality differs
Because it is a natural product, differences in composition and appearance are not consistent. Fluctuations are normal to a certain extent. Nevertheless, you should check some criteria to get an indication of the product quality.
composition
High-quality bark mulch is characterized by purity. Filling materials are often included in cheap products, because the cost of foreign substances can be effectively reduced. It is not uncommon for you to find chopped wood scraps, green compost, stones, plastic parts or broken glass in the packaging from discount suppliers.
grit
The particle size must be within a specified range, which is stated on the packaging. This extends from 18 to 60 millimeters. Manufacturers of discount products dispense with work steps such as screening 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 cannot be guaranteed.
residues
While visual defects are easy to spot, contamination and toxins can only be identified using laboratory methods. In addition to germs, which reduce the compatibility of the material with plants, the tree bark can contain insecticide residues. This is more often the case with raw materials from abroad, because pests such as the bark beetle are fought here 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 levels in the products do not exceed the limit of 1.5 milligrams per kilogram of dry matter.
odor
Another sign of poor quality is a strong or musty scent. This indicates that the bark mulch is older and already subject to decomposition processes. Such aromas indicate suboptimal storage. A fresh substrate does not smell unpleasant or earthy, but pleasantly like forest.