One of the most common errors made by homeowners is cutting their lawn too short. While the reasons are feasible—taking more off to reduce how often it needs mowing or cutting it low to make it look like a well-manicured golf course of putting green—the practice is unhealthy and damaging.
The turf cultivars grown on golf courses are known as “fine turf” types. These grasses are highly specialized cultivars that have been developed to tolerate frequent, closely-shorn mowing. The grasses we typically grow in our lawns are different cultivars that are not genetically capable of handling being cut short.
When you cut your lawn too short, it weakens it overall, and your grass may end up looking thin and patchy instead of thick and lush. When done over and over again, it can even kill the grass.
So, why is it actually harmful to cut your lawn short?
- Grass blades are like tiny solar panels for the plant, trapping chemical energy for photosynthesis to make food. Cutting the blades short limits the grass’ ability to store this energy from the sun, so photosynthesis is affected. In turn, the blades can’t produce as much glucose to drive metabolic processes, and growth is severely impacted.
- The grass blades also act as tiny warehouses, storing water, carbohydrates, and proteins. When the plant is stressed—during times of drought, for instance—it can pull from these reserves to stay alive. But if the storage space is significantly reduced because the grass is cut too short, then the plant has limited resources to rely upon during times of need.
- Cutting grass too short can cause crown damage to the individual plants. Instead of growing, the grass directs its energy to heal the injury.
- Shorter grass allows more light to infiltrate the soil surface, triggering weed seed germination. The weakened, stressed grass can’t out-compete the seedlings.
- Grass has natural self-defense mechanisms to protect itself from insects and diseases. When stressed, this gene expression is turned off to direct energy towards healing instead, and the turf is more susceptible to problems.
- If the grass’ energy is directed to new shoot growth instead of root development, the roots won’t continue to grow deeper and are all found in the uppermost layer of the soil. The shallow roots are more intolerant of drought.
- Short grass offers little shade to the plant’s crowns, increasing the chances of summer heat stress. With fewer water reserves in the short blades and a shallow root system that cannot access water held lower in the soil profile, the grass struggles to combat the heat stress.