Grass is green because of chlorophyll.
Chlorophyll is a pigment plants use to capture light energy for photosynthesis.
But the interesting part is what chlorophyll does not absorb strongly.
Chlorophyll absorbs some colors better than others
Visible light contains different wavelengths that we perceive as different colors.
Chlorophyll absorbs red and blue wavelengths strongly.
Green wavelengths are absorbed less strongly.
More green light is reflected or transmitted.
That green light reaches your eyes.
What does the plant do with the absorbed light?
Plants use captured light energy to help make sugars from carbon dioxide and water.
Those sugars provide energy and building material for growth.
Photosynthesis is therefore the reason the pigment matters biologically.
Is green light useless to plants?
No.
The simplified statement that plants “do not use green light” goes too far.
The recorded script’s core point is narrower: chlorophyll absorbs green wavelengths less strongly than red and blue, so more green light reaches your eyes.
Are there other pigments in grass?
Yes.
Plants contain other pigments too.
Healthy grass usually looks green because chlorophyll dominates the visible color.
When chlorophyll breaks down or other pigments become easier to see, plant color can change.
That same principle helps explain why leaves change color in the fall.
Why can grass look different shades of green?
Species, health, nutrition, light, moisture, and pigment concentration all affect appearance.
The basic chlorophyll explanation remains the same.
Why does cut grass still look green?
Cutting triggers chemical changes and creates the familiar fresh-cut grass smell, but the chlorophyll does not instantly vanish.
The blades remain green until pigments and tissues change further.
So grass is not green because green light is especially eager to live there.
It looks green partly because green is the light chlorophyll did not absorb as strongly.
And that’s the short explanation.
Related explanations: Why do leaves change color in the fall?, Why does freshly cut grass smell?, and Why do pine trees stay green in winter?