Sanding your lawn - professional tips for the perfect lawn

"Regular sanding helps to break down thatch in the lawn."

Furthermore, especially on older pitches, sanding is necessary to maintain the functionality of the turf-bearing layer, particularly on the surface and in the near-surface area, in terms of its grain size distribution and its content of organic matter.

Over time, virtually all pitches experience a beneficial earthworm activity for soil turnover and aeration, but this is linked to the deposition of fine particles from deeper layers onto the surface. Furthermore, the breakdown of thatch, also due to microbiological factors, leads to a concentration of more or less finely structured organic matter on the surface or, caused by stud impressions, in the upper layer of the turf.

Both processes restrict water permeability, increase water retention at the surface, and in extreme cases lead either to surface crusting or to a spongy texture. These negative effects can be counteracted by timely topdressing with sand, unless regular aeration and distribution of the fine-crumbly, humus-poor excavated material from the turf layer achieves the same effect.

Sand quantity and frequency

The amount and frequency of sand application depend on the degree of alteration of the turf's root zone. Generally, an initial topdressing in spring with approximately 2 to 3 liters of sand per square meter should suffice. This spring topdressing is recommended after reseeding.

During the lawn season, regular, light sanding (also called topdressing) with 0.5 to 1.5 liters of sand per square meter is recommended.

However, if strong earthworm activity leads to a greater deposition of fine-grained and humus-rich material on the surface of the turf layer, a second topdressing with the same amount of sand is necessary in late summer or early autumn.”

Note from 100proGreen:

In home gardens, a standard turf substrate layer (DIN 18035-4 or DIN 18035-1) is typically not present. Therefore, it is recommended to apply 0.5-1.5 liters of sand per square meter every four to six weeks (topdressing) to very clayey or fine-textured soils.

"In cohesive subsoil, earthworm castings always represent a mixture of subsoil and turf-bearing layer, enriched with turf-derived organic matter. Therefore, in standard sports field constructions, earthworm castings never consist entirely of clay or sand."

Sand quality

Sands suitable for resurfacing must be resistant to wear and weathering. Consequently, quartz sands or sands with a low soluble lime content are primarily considered.

In order to achieve the required "leanness effect", sands must also be largely free of silt particles; therefore, primarily washed sands should be used.

The sand grain size must guarantee infiltration into the scar, sufficient texture change, and adequate shear strength.

For regular sand recoating, a finer (0/1 - rich in fine sand) and a coarser (0/2 - low in fine sand) grain size can be used alternately to ensure shear strength. This also applies to the use of lava, where, for reasons of risk of injury, particular attention must be paid to a very low proportion of gravel (> 2 mm).

Note from 100proGreen:

We recommend a grain size between 0.4 and 1.8 mm. Especially in highly compacted soils, the grain size should be closer to 0.8-1.8 mm.

Source: DFL brochure Sports field construction and maintenance, 5th revised edition (2017)