Last updated on October 23rd, 2023 at 08:58 pm
Are you wondering what mineral mulch materials are and where they are used?
In addition to these questions, you will learn here what mineral materials are available for mulching and what the advantages and disadvantages of the different mulch materials are.
After reading this article, you should have found the right mineral mulch material for your purposes.
Mineral mulch consists of inorganic, that is, non-living, crystalline components. Due to these properties, mineral mulch materials can not burn or decompose. On the contrary, mineral mulch, such as various types of rock in the form of gravel, chippings or even lava, is very durable and weathers only slowly due to erosion.
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What are mineral mulch materials
Mineral mulch materials, unlike organic mulch materials, are non-flammable and consist of inorganic, non-metallic but crystalline components. All types of rock, such as shale or quartz, thus count as mineral mulch materials.
Due to these components, mineral mulch materials almost do not decompose, or if they do, they decompose very slowly via erosion. As a result, mineral mulch materials require very little maintenance.
Depending on which material is used for mulching, nutrients or certain minerals contained in the rock types are released into the soil.
Overall, mineral mulch materials are used more for visual beautification of the garden to create a uniform, well-groomed appearance.
Mineral materials are used primarily for mulching rock gardens, perennial beds or, in some cases, herb beds.
However, depending on the type of rock or material and size of the area to be mulched, mineral mulch materials can quickly become more expensive.
If you want to know more about the difference between mineral and organic mulch materials, check out the article I linked to on the right.
What are the mineral materials for mulching
Gravel for mulching
From quartz gravel to ornamental gravel, it comes in different varieties and colors. In contrast to chippings, gravel is always ground round.
Especially for paths gravel is suitable as a mulch material. For this purpose, a layer of 5-10 cm should be spread.
Most types of gravel are light and therefore do not heat up in the sun. This can be an advantage if you like to walk barefoot in the garden.
With quartz gravel, however, it should be noted that it is very heavy and therefore should not be spread on dense clay or loam soils. Otherwise, these would become even more compacted due to the weight of the gravel.
Grit Chippings for mulching
Chippings, unlike gravel, have rough, sharp edges and, like gravel, range in diameter from 2 to 63 mm.
Chippings are very suitable for mulching paths, as the sharp broken stones tilt into each other to form a stable and flat surface.
In particular, brick chippings are also suitable for mulching in the garden. Brick chippings are very cheap, and open-pored, which is why they retain water and heat very well.
If you mulch the garden or some paths with brick chippings, you must be aware that the light brick color is very contrasting, which is not to everyone’s taste.
Lava mulch for the garden
Lava is a brown to reddish rock that is mostly used for mulching rock gardens or even smaller areas in the garden.
Due to its porous structure, lava has an excellent water absorption capacity and then slowly releases it into the soil.
In addition, lava contains many nutrients and minerals such as magnesium, boron or iron, which are slowly but steadily released into the soil over time through weathering, thereby fertilizing it.
Shells as mulching material
Shells can also be used for mulching in the garden. Since the shell consists mainly of lime, this is slowly washed out and released into the soil.
When the garden is mulched with shells, the pH can therefore slowly increase over time as the lime it contains has an alkaline effect.
The advantage of mussels as mulch material is that they can be collected in small quantities at least even on the beach and also a hurdle for snails.
Slate quarry for mulching
In contrast to gravel, slate is a dark rock, which is especially suitable as a quarry for mulching.
Because of its dark color, it heats up very quickly in the summer, which can be a disadvantage in two ways:
Plants that have their leaves down to the ground, such as lavender, can get burned by the very hot slates
This can also happen to you if you have used slate on paths for mulching and like to walk barefoot through gen garden.
Therefore, broken slate for mulching is best used in the shade or partial shade.
Travertine for mulching
Travertine is a porous limestone that is usually light or yellowish or ocher and is very suitable for mulching in the garden.
Travertine has the advantage that it is lighter than other stone due to its porous structure and can therefore be spread very well on heavy soils as mulch material.
In addition, due to the larger surface area, the stone stores water or moisture through the pores and can release it into the soil over time.
However, since it is limestone, you should note that travertine can slightly raise the soil pH.
Diabase for mulching
Diabase is a fine- to coarse-grained stone that can have different colors, from blackish green to grayish green.
Diabase, or greenstone, is also very suitable for mulching in the garden, mainly due to two significant advantages.
On the one hand, greenstone is quite inexpensive compared to other types of rock. Thus, even larger areas or parts of rock gardens can be designed with it inexpensively.
In addition, greenstone has a very beautiful color spectrum in its different colors and shades of gray, which is well suited for mulching. Diabase is not quite as dark as slate, for example, and therefore does not heat up as much. However, greenstone isn’t quite the same as quartz or regular gravel either, so it makes a great contrast in the garden.
If you mulch with diabase, however, you should know that this stone is slightly alkaline. This means that it can cause the soil pH to rise slightly over time.
However, this is generally not a problem, since the soils here in Central Europe slowly acidify over time anyway, due to leaching.