Proper mowing increases the density of the lawn, which in turn decreases weeds. Each type of grass has a recommended mowing height. Find out which type of grass is in your lawn (you may have more than one) and mow at the proper height.
Stick to the 1/3 rule — never remove more than 1/3 of the grass blade length at any one time. A healthy lawn can survive an occasional close cut. Repeated close mowing produces a brown lawn and has several harmful side effects, including:
• Injury to the crown, where new growth generates and nutrients are stored.
• Reduction of the surface area of the blade, making the blade surface insufficient to produce food through photosynthesis.
• Increased vulnerability to pests and disease.
• An increase in the sunlight reaching weed seeds, allowing them to germinate.
• Risk of soil compaction.
 
Also remember to:
• Mow when the grass is dry. The blades will be upright and less likely to clump when cut.
• Avoid mowing in the heat of the day to prevent heat stress on your grass and yourself.
• Keep mower blades sharp and balanced. Ragged cuts made by dull blades increase the chance of disease and pests.
• Change the mowing pattern each time you mow. Grass develops a grain based on your cutting direction, tending to lean towards the direction you mow. Alternating the pattern causes more upright growth and helps avoid producing ruts in the lawn.
• Mow moving forward, whether you're pushing a walk-behind mower or sitting behind the wheel of a lawn tractor.
• Discharge the clippings (unless you bag them) towards the area you have already cut.
• Leave clippings on the lawn unless they form clumps or rows. This technique (known as grass cycling) returns nutrients and nitrogen to the lawn.
• Consider using a mulching mower or mulching attachments.
• If you bag your clippings, consider composting them.
• Mow grass higher in shaded areas under trees. In these areas grass has to compete with tree roots for water and nutrients.
• Reduce mowing frequency and raise the mowing height of cool-season grasses when hot, dry weather slows their growth rate.
• Follow the proper fertilizing schedule for your type of turfgrass.