The most important way to maintain a healthy lawn is to keep your grass at a minimum mowing height of 2.5 to 3 inches. This advice may be surprising: many suburban lawns are kept much shorter. The reality, however, is that keeping your grass a bit longer has a number of important benefits.
A longer lawn means that the individual grass blades (the leaves) have more surface area for photosynthesis to occur. Increased photosynthesis results in more plant growth, a more extensive root system, and a healthier plant. In the long run, that means less need for fertilizer, aeration, and other time-consuming lawn maintenance.
Weeds are drastically reduced when the lawn is maintained at a higher cut. Once turf adapts to growing at increased heights, it fills in and becomes dense and lush, crowding out weeds that normally invade when turf is weak and stressed. Longer grass also means that the ground is more shaded, so that weed seeds do not get the sunlight they need to sprout. Fewer weeds mean less time spent removing weeds, less use of herbicides, and more time enjoying your lawn.
Lower Need for Water
A dense, lush lawn maintained at a minimum height of 2.5 or 3 inches is more tolerant of infrequent watering and drought stress because there are increased moisture reserves in the leaf tissue and root system. Although your turfgrass will still need water when mowed higher, the effects of drought or community watering restrictions will be less noticeable and will take longer to occur, This can be the difference between your lawn turning brown or making it until the next rain.
Lusher, Greener Appearance
The most noticeable benefit of the longer turf is aesthetic. The increased amount of leaf blade surface makes for a dramatic improvement in turf color. After shifting to a higher mower height, you will find that the lawn becomes consistent, uniform, and lush looking. When given the right opportunity, shade zones, patchy areas, and weak spots in the lawn will fill in to achieve the dense carpet effect that every homeowner wants.
Your 2.5- or 3-inch lawn will need to be mowed once a week during the growing season, but contrary to popular belief, it will not cause you more work. Once the grass reaches that uniform height, you will still be cutting off the same amount of grass with each mowing.
Of course, there are exceptions to every rule and this one is no different. Some southern grasses just don't like to grow that high and thrive just fine at lower heights. Also, in moist or wet climates, some lawn care experts advise giving your lawn a shorter "buzz cut" before winter snows come. This will keep the lawn from trapping a lot of moisture that can lead to fungal problems in the spring. Long grass can also be a haven for voles and other tunneling rodents seeking shelter under the snow in winter.