Grass does change color in the fall, though the transformation is less dramatic than the vibrant reds and oranges seen in deciduous trees. As temperatures drop and daylight hours shorten, the lush green of a lawn transitions to shades of yellow, tan, or straw-brown. This change prepares the grass plant to survive the upcoming cold season. The process shifts the plant’s focus from active growth to preservation, initiating chemical changes that alter the visible color of the leaf blades.
The Chemistry of Color Change
The loss of vibrant green color results from the plant ceasing chlorophyll production. Chlorophyll is the pigment responsible for capturing sunlight during photosynthesis. As fall signals intensify—cooler temperatures and reduced light—the grass plant begins to dismantle these molecules.
This breakdown is a survival strategy, allowing the plant to reclaim nutrients like nitrogen and magnesium from the leaf blades. These resources are then stored in the crown and root system. Once the dominant green chlorophyll is degraded, its masking effect is removed, allowing other pigments present throughout the summer to become visible.
Why Grass Doesn’t Turn Red or Orange
When chlorophyll disappears, the underlying pigments become exposed, primarily carotenoids and xanthophylls. These compounds produce yellow and orange colors and are present in the leaf blades all year long. This exposure causes the lawn to show a brief period of yellowing before fading completely.
Grass rarely achieves the deep crimson and scarlet colors of maple or oak trees due to minimal anthocyanin production. Anthocyanins are the red and purple pigments actively synthesized by many deciduous trees in the fall in response to sugar accumulation. Turfgrasses do not typically produce these pigments as a widespread natural mechanism of fall coloration. Instead, the exposed yellow and orange carotenoids are quickly overtaken by the final stage of color change: the leaf blades dry out and die back, leaving behind the dull, tan, straw-colored cellulose structure.
Entering Winter Dormancy
The final tan or brown color signals that the grass has entered winter dormancy. Dormancy is a protective survival mechanism triggered by consistently cold soil temperatures (typically below 50 degrees Fahrenheit) and shortened day length. The plant is not dead; it is resting, drastically reducing its metabolic activity to conserve energy and water.
During this period, the above-ground leaf blades are sacrificed and senesce, contributing to the brown, straw-like appearance. The crown, which is the living portion of the grass, remains alive just above the soil line, protected by the soil and dormant leaf material. The crown and root system are packed with stored carbohydrates, acting as an energy reserve to fuel new green growth when warmer temperatures return in the spring.