We are all aware of the typical smell of cut grass, it does not matter if we are using a lawnmower or another tool, our nose will perceive that smell in any case. characteristic smellfor some almost pleasant. Have you ever wondered what its origin is? Well, the smell we are talking about is not a normal “flower” scent, but the result of a real one chemical mechanism which comes into action when we cut the grass on our lawn. It’s as if we were mowing the grass damaging the plant itselfwhich reacts through the smell we smell. In short, that aroma is given by volatile molecules – nothing more than chemical compounds that easily “fly” into the air in the form of gases that we can smell – that grass produces when its cells are broken down. Let’s talk about green leaf volatiles, “volatile compounds of green leaves”: organic molecules containing oxygen that are released into the air when cut. In short, when we cut it, the grass is actually screaming “ouch!” in his own way.
How the smell of cut grass is released: GLVs
When the lawnmower passes by and that unmistakable scent wafts up, we are actually “listening” to the chemical melody of the plants. The grass, “wound” from the cutreleases a series of small volatile molecules, green leaf volatiles (GLVs), which are released into the air when the grass plant cells break down. These molecules arise from natural fats present in the leaves: when they are damaged, the enzymes they transform them into odorous compounds. Let’s talk about simple chemicals, like aldehydes and alcohols, that the air quickly brings to our nose. One of these, called (Z)-3-hexanal, is mainly responsible for the characteristic “smell of greenTiny quantities are enough for our brain to perceive it: this is why even a single pass of the blade fills the garden with odors.
The release of these molecules is not constant: increases immediately after cuttingthen gradually decreases as the surfaces slowly dry out. The intensity also depends on climate and humidityon a hot and sunny afternoon the aroma is stronger, while after the rain it is weaker.
In reality, the scent of cut grass is not just a sort of side effect: it is a real one for the plant message. In fact, these substances serve to signal a danger to nearby plants, which thus activate their own defense mechanisms. Some studies show that they are also attracted insects “good” for plants, predators of those that feed on the leaves. In short, while we smell our garden, the lawn is communicating in code that it is under attack and is reacting, in its own way.
Human perception: why we like that perfume
For many of us humans, the scent of cut grass is perceived as pleasant. It is a fact that has a real scientific basis because of some factors. First, some of these molecules have a low odor threshold, so already small quantities are clearly perceptible and recognisable. Furthermore, GLV molecules are similar to those that plants release when vegetables or fruits ripen or are cut. Finally, since the scent is strongly “green”recalls mental associations with nature, freshness, open spaces and a general feeling of relaxation.
In fact, there is also an important psychological aspect: who he associated pleasant moments to the well-kept lawn and garden, often connects that scent to positive memories, making it more pleasant, even if, in reality, our lawn is screaming “help!”.
