Why Does Fresh-Cut Grass Smell?

Do you love the fresh-cut grass smell? Are you one of those people that inhales deeply when passing someone mowing the lawn? What you are smelling is the grass’s emergency distress signal.

Green Leaf Volatiles

When your mower blades cut the grass, the grass starts producing green leaf volatiles or GLVs, for short. It is these GLVs that we smell.

The GLVs do several things to help the plant. Some green leaf volatiles increase new cell growth at the wound site for faster healing.

Since plants are at risk for bacterial infections when damaged, some GLVs act as an antibiotic to keep the disease from happening. Then others send out distress signals.

All plants send out these GLVs when damaged, whether damaged by pruning, insects, or mowing.

Green Leaf Volatiles and Insects

parasitic wasps on a hornworm — Parasitic Wasp Eggs on Caterpillar

What is most interesting is that the GLVs also attract beneficial insects to the plants.

If a caterpillar is chewing on a plant, the plant sends out its GLVs; think of it as a plant’s “bat-signal.” Parasitic wasps pick up the signal and rush to the caterpillar. It lays its eggs in the caterpillar, eventually killing it.

Because we can’t sense the GLVs as well as insects, we don’t “smell” the minor releases of GLV when a single plant is injured. The grass produces a large amount of the GLVs when cut. A vast amount of GLVs gives us that overwhelming grass scent.