Why do the parks in Milan have tall grass?

Recently, the Municipality of Milan announced that, once again this year, in certain green areas of the city, the grass will be cut less frequently, intentionally allowing it to grow more than usual. This practice is called "reduced mowing" and in recent years it has been implemented in various other European cities including Dublin and Frankfurt. The goal is to increase biodiversity in green areas, meaning the variety of species present in the environment, an important parameter to assess the health of parks and gardens. The higher the degree of biodiversity, the better a natural environment functions, from various perspectives. And this is especially true for those in urban centers. In green areas where grass is often cut, there has been a greater presence of insects considered harmful to humans – such as mosquitoes or ticks. Conversely, in parks and urban gardens where the grass is left higher, there has been an increase in the number of bees, ladybugs, and butterflies, which through their pollination activity of plants promote the health of natural ecosystems. A greater variety of insects means more food for other animal species, such as some birds.

Since it contributes to increasing the levels of biodiversity in an environment, "reduced mowing" is a practice recommended by the scientific community itself. There are also economic benefits: in this way, it is possible to save funds for the management of public vegetation. The measure of the Municipality of Milan was announced by the Councilor for the Environment and Greenery Elena Grandi, after it had already been discussed and experimented with last year. Specifically, the initiative will involve 54 green areas covering 1 million and 300 thousand square meters, which will be indicated by special signs explaining the practice of "reduced mowing". The municipality has mainly selected those grassy areas that are usually not frequented by citizens, but there will also be one inside the Porta Venezia park.

Why it's Better Not to Cut Grass in Cities

In general, insects are animals that can potentially thrive even in urban centers because they can prosper in small environments, such as gardens and parks found in cities. The spread of this awareness, combined with the benefits brought by uncultivated grasslands in terms of biodiversity, has favored the emergence of a movement that brings together researchers, scholars, and activists, who have long been denouncing the negative consequences of keeping lawns constantly manicured. Maintenance, irrigation, and other practices that make green areas aesthetically more pleasing, in fact, not only discourage the presence of insects but are also associated with less plant biodiversity, which in turn contributes to the spread of invasive plants. Conversely, a greater amount of vegetation reduces soil erosion and allows for the absorption of a more substantial portion of solar radiation, thus also containing soil heating on hotter days. In areas with more concrete and fewer green spaces, so-called "heat islands" are more easily created, which are indeed hotter than adjacent areas. Between 2017 and 2021, it was calculated that in Milan, the average summer surface temperature recorded at 10 a.m. in green areas was below 34 °C, while in more concrete areas it exceeded 36 °C. Some have criticized the initiative of the Municipality of Milan, suggesting that tall grass simultaneously promotes the proliferation of mosquitoes, causing more inconvenience to the population. However, the opposite would be true: as entomologist Leonardo Forbicioni argues, an increase in biodiversity would also favor the presence of species that prey on mosquitoes: "Increasing the rate of biodiversity, even in small areas such as flowerbeds or gardens, can only be beneficial to the overall balance between species."