The average annual temperature in cities is higher than in rural areas. The main reason is the low amount of green spaces which could cool down the air. Additionally, buildings and asphalt store the heat generated during the day and release it again at night. In combination this can result in extreme heat in the summer. Green roofs, in contrast, store and evaporate water, thereby lowering the temperature. They also reduce floods as they absorb some of the water when it rains heavily. Green roofs also provide habitat for many plants and animals that are otherwise found only on colourful meadows.

Our example roof shows three different substrates, with one not being planted at all and the other two being planted differently. The green plots require different amounts of work input.

Information to lava substrate | General informations about green roofs

Section A: Pebbles

This roof is covered with gravel. Although it only offers a minor cooling effect, it does not require any upkeep. Even a roof with gravel is better than a roof with black tar paper. After all, as time goes by moss can start growing between the pebbles. The pebbles also offer small animals shelter during the hottest time of the day.

Section B: Frugal stonecrop

A mineral-organic substrate (lava, pumice, compost, bark humus) was laid to a height of 15 cm on this section and planted with different species of stonecrop (genus Sedum). Stonecrop is extremely frugal and survives for many weeks without rain, as it stores water in its fleshy leaves. It also offers insects nectar and pollen.

Section C: Intensive greening

A mineral-organic substrate with a high level of organic matter (loess, lava, pumice, sand, compost) was laid to height of 30 cm for this species-rich green area. This however requires a sturdy roof. The seeded garden herbs and wildflowers can get by with the rainwater stored in the substrate. They should nevertheless be watered from time to time in the event of longer periods of drought.

Stadt Leipzig

The city of Leipzig supports the objectives of the National Biodiversity Strategy. Green roofs can partially compensate for lost habitats. The green roof strategy of the city of Leipzig points to the potential of roofs for promoting nature conservation. The Leipzig green roof mix with many native plant species helps maintain and bolster biodiversity in the city. Learn more at

Photos section A, B und C:

Photos from the marsh plant roof:

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