Certified Professional Horticulturist (CPH) Practice Exam

When mowing a lawn, how much of the leaf blade is recommended to be removed?

1. One-quarter

2. One-third

3. One-half

4. Two-thirds

The correct answer is: One-third

When mowing a lawn, it is recommended to remove no more than one-third of the leaf blade at a time. This practice is beneficial for maintaining the health and vigor of the grass. When more than one-third is cut, it can put excessive stress on the grass plants, leading to a decline in health. Cutting less than one-third allows the grass to photosynthesize effectively and recover more easily from mowing. This method helps in ensuring that the lawn remains lush and green, minimizes lawn stress during periods of heat or drought, and reduces the risk of scalping, which can expose soil and lead to weed invasion. Maintaining proper mowing height and frequency is crucial for a healthy lawn, which is why the one-third rule is a widely accepted guideline among horticulturists and lawn care professionals.