Lawns and the environment: what a lawn does and how to care for it more sustainably
Hardly any garden surface is judged as differently as the lawn. For some it is a green lung and a playground, for others a species-poor monoculture that consumes water, fertiliser and petrol. Both are partly true. Here you can read what a lawn actually does for the environment, where the criticism is justified and how to care for your lawn so that it does the environment more good than harm.
In short
- A lawn lets rain soak in, protects the soil from erosion, cools through evaporation and stores carbon in the soil.
- Compared with paving, gravel or artificial turf, it has a clear advantage. Compared with a wildflower meadow, it is poorer in species.
- Justified points of criticism are low biodiversity, water use in summer, too much fertiliser, petrol mowers and robotic mowers running at night.
- With the right care, much of this can be avoided: mulch, feed according to need, water sparingly, mow without emissions, let the edges flower.
What a lawn does
Rain soaks in instead of running off
A closed sward on loose soil absorbs rainfall and releases it slowly to the subsoil. On sealed surfaces the same water runs into the sewer, during heavy rain often faster than the sewer can take it. The more compacted the soil, however, the worse this works for a lawn too. A regularly aerated lawn absorbs considerably more than a trampled one.
Protection against erosion
The dense root network of the grasses holds the soil in place. On embankments and after building work, sowing grass is therefore often the quickest way to protect bare soil from being washed away by rain or blown away by wind.
Cooling through evaporation
Grasses release water through their leaves and in doing so cool themselves and their surroundings. On hot days a lawn therefore stays considerably cooler than asphalt, paving or artificial turf, which can heat up to more than 60 °C in the sun. The cooling effect depends on water, though: a dried-out, brown lawn hardly cools at all. Trees and shrubs, which also cast shade, cool even more.
Carbon in the soil
Grasses constantly form new roots, and dead roots become humus. Studies show that lawn soils accumulate carbon over the years. Part of this effect, however, is used up again by maintenance: by petrol mowers, by the production of nitrogen fertiliser and by nitrous oxide escaping from over-fertilised soils. How the balance turns out therefore depends strongly on how you care for your lawn.
Binding dust and life in the soil
The large leaf surface of the grasses catches dust from the air, which the next rain washes into the soil. And below the sward there is more life than you can see: earthworms, springtails, fungi and countless microorganisms that break down organic material and keep the soil loose.
Good to know
You often read that just a few hundred square metres of lawn supply several people with oxygen. Such figures should be treated with caution. Grasses do produce oxygen, but over the year a large part of it is consumed again when clippings and dead plant parts break down. The real benefit of a lawn lies rather in soil, water and the local climate.
Where the criticism is justified
| Criticism | What is behind it |
|---|---|
| Low biodiversity | A closely mown lawn of a few grass species offers insects hardly any flowers or food. A wildflower meadow is clearly superior here. |
| Water use | In dry summers a lot of drinking water is used for irrigation, often more than necessary and at the wrong time of day. |
| Fertiliser and pesticides | Too much nitrogen is washed out or escapes as nitrous oxide. Pesticides harm soil life and insects. |
| Petrol mowers | Small combustion engines emit comparatively large amounts of pollutants per hour of use and are noisy. |
| Robotic mowers at night | Hedgehogs are active at night. They do not flee but roll up and are badly injured by the blades. Several German cities have therefore banned night-time operation. |
None of these points is a property of the lawn itself. They are consequences of how it is cared for. That is exactly where you can make a difference.
Lawn compared with other surfaces
If you compare a lawn with a wildflower meadow, you mainly see its weaknesses. But you cannot walk on a meadow, it does not tolerate football games or a garden table. In many gardens the realistic alternative to a lawn is not a meadow but paving, gravel or artificial turf. And compared with these surfaces, a lawn performs better on almost every ecological point. Gravel gardens are now explicitly prohibited in some German states, such as Baden-Württemberg.
A good middle ground is often a combination: lawn where people play and walk, herb lawn or flower strips at the edges and in corners that are hardly used.
Caring for your lawn more sustainably
Mow without emissions: a hand reel mower needs neither petrol nor electricity, is quiet and cuts the blades cleanly like scissors. For larger areas, battery mowers are a good alternative to a petrol engine. More in Lawn mower types compared.
Leave the clippings: fine clippings break down within a few days and return part of the nutrients. That saves fertiliser and disposal. When this works is explained in Lawn mulching.
Feed according to need: moderate amounts several times rather than one large dose, preferably organic or slow-release. A soil analysis every few years shows what is really missing. More in Feeding your lawn the eco-friendly way.
Save water: water in the early morning, infrequently and deeply, ideally with rainwater from a tank or butt. A lawn that turns brown in high summer is usually not dead but dormant, and it greens up again after the next rain. Everything about watering in Watering your lawn.
Robotic mower by day only: set the robotic mower so that it only runs in daylight, and check the area briefly beforehand if hedgehogs live in your garden.
Let the edges flower: clover, daisies and selfheal in the lawn are not a disaster but food for insects. If you like, leave a strip at the edges that is only mown two or three times a year.
Soil instead of chemicals: moss, waterlogging and gaps usually have a cause in the soil. Aerating and top-dressing solve the problem for good, without moss killers or weed killers.
Frequently asked questions
Is artificial turf more eco-friendly because it needs no water?
No. Artificial turf is made of plastic, releases microplastics, heats up strongly in the sun, offers no habitat and has to be disposed of after a few years. A natural lawn has a clear ecological advantage.
Should I turn my lawn into a wildflower meadow?
On areas you hardly walk on, that is a good idea. For areas where people play, walk or sit, a lawn remains the better choice. A combination of both is often ideal.
How much water does a lawn need?
On hot days a lawn evaporates several litres per square metre. Rather than a little every day, it is better to water deeply about once a week. A brown lawn in summer dormancy does not necessarily need watering.
Is a robotic mower bad for the environment?
Not in principle. It mows electrically and mulches. The problem is running it at dusk and at night, when hedgehogs and other animals are out.
Featured image: kate, stock.adobe.com
