Late fall always reminds us that we definitely don’t live in the tropics. Vibrant green lawns give way to a sea of straw colored blades. You may have wondered to yourself, “Why is my grass brown?” Let’s take a look at the science behind winter dormancy in lawns.

The crown matters

Grass leaves and roots meet at an important part of the plant – the crown. As long as it stays alive, so does the grass. One of the crown’s functions is to endure brutal winters. During the cold months, it may appear to be dead, but it’s really just dormant. When weather conditions improve in the spring, it will produce new leaves and roots.

The light at the end of the season

The end of daylight savings time was a jarring reminder that our days are getting shorter. The northern hemisphere has been tilting away from the sun since the summer solstice. The sunlight that reaches the ground comes from a steeper angle and travels through more of the atmosphere. The strength of the light decreases significantly. Because grass needs sunlight for photosynthesis, it will enter dormancy without it.

Resupplying the soil

Plant leaves that were once green are recycled into the soil. This provides space for new leaves to emerge in the spring. It also adds nutrients to the soil below for the next round of grass. Microbes in the soil and foliage aid the cycle by breaking down plant matter.

Left out in the cold

Your lawn stores water during the warmer months. When temperatures fall, the grass loses this water to prevent freezing. Instead, it builds up concentrations of salt within plant cells. This protection measure allows growth again in the spring. Frozen soil also hinders plant growth in the winter because grass roots cannot expand or take in moisture.

Remember not to worry if your lawn is getting a little less green this time of year. Dormancy is a process that occurs naturally. It protects the grass through the harsh winter chill and ensures a beautiful green lawn in the spring.