Preserve biodiversity and utilize soil as a water reservoir.

Trillions of organisms thrive beneath our feet, requiring water and air for survival. When an impermeable layer like asphalt covers the ground, these organisms no longer receive the resources they need to survive. Maintaining open spaces fosters a healthier underground ecosystem and promotes the health of plants above ground. Precipitation, evaporation, and collection form a functioning water cycle. Sealed surfaces disrupt this cycle, causing rainwater to flow unused into the sewage system, leading to floods or overheating. Using permeable materials such as wood chips, gravel, or open-pore stones in walkable garden areas helps mitigate these issues.

Soil acts as a water reservoir 

Amidst climate change and the corresponding increase in extreme weather events such as heavy rainfall or prolonged dry spells, it has become increasingly important to manage rainwater in the garden. “Open” ground can absorb and store rainwater well, with excess water infiltrating into the groundwater, concluding the water cycle.  

If the soil is sealed with an impermeable layer (e.g. with paved stones), rainwater is unused and flows back into the sewer or causes flooding in other areas. The rainwater is irretrievably lost for the soil, plants, and groundwater formation in this garden. Therefore, the goal in every garden should be to close the water cycle and keep rainwater in the garden system.  

Preserving Organism Diversity in Soil 

Sealing the ground interrupts the exchange of air and gases between the soil and the atmosphere.  Countless soil organisms die due to the loss of rainwater and the transport of gaseous substances. This can result in a decline in soil fertility, as it can only be created through the work of a diverse group of organisms.  

What can gardeners do? 

• Design walkable garden areas (seating areas, playgrounds, etc.) in a nature-friendly manner, i.e. using wood chips, permeable gravel, grass grids, etc.   

• Reduced sealed sidewalks... 

  • ... by narrowing their surface area, since not every garden path requires the width of a sidewalk. 

  • … by reserving them for certain paths only, e.g. to the compost, and using individual steppingstones whenever possible 

  • … by paving main paths around the home with permeable porous stones or grass pavers, using a mixture of topsoil (30%) and sand (70%). Winged insects can use this area for nests, while plants germinate in the crevices, creating a harmonious mixture of stone and greenery.  

Special Feature: Green Roofs 

Green roofs can be created to offset the impermeable areas caused by homes and garages. These spaces provide a reliable habitat for many plants and animal specials instead of remaining barren, desolate areas. Additionally, these roofs act as buffers for extreme weather events by capturing rainwater and improving the surrounding microclimate through evaporative cooling during heatwaves. The greenery also acts as additional insulation, keeping buildings cool in the summer and reducing heat loss in the winter.   

Those wishing to green their roof must inquire about their building’s load-bearing capacity first and seek advice from professionals regarding drainage as well as the substrate and plant selection. The practical implementation and subsequent Maintenace work (close to none) can be carried out independently. Smaller roofs, such as bin covers or bicycle sheds, can be greened entirely by yourself using lots of imagination. And remember, every square meter of green space matters! 

Tip:  Even planting a bit of moss can store around 15 l water / m².