Mowing is an essential part of maintaining a landscape. It prevents volunteer tree seedlings and brambles from developing into maturity. It makes life miserable for most weeds. Weeds struggle when forced to remain less than 6 inches tall. Some weeds have adapted to overcome this, though. A lot of lawn weeds have adapted to mowing and stay very low, or at least keep some of their seed-producing heads below mower blade height. Others, like hop clover, send up flowers so quickly they are able to disperse seed between mowings, like dandelions. Our go-to maintenance activity for lawns and to prevent lawn weeds does eliminate the majority of turf weeds.
I used to have a neighbor that thought a beautiful lawn should be mowed as closely as a golf green, but he only mowed twice a year. Twice a year he mowed his lawn within ½ inch of the ground, and twice a year we would see plumes of red clay waft into the air as his riding lawn mower chopped away at the uneven ground surface. His low mowing would kill any surviving turf grass blades, and the disturbed ground would quickly grow back into weeds. It was not a golf-course look!
Mow strategically. Time your mowing to make your turf grass the healthiest species on the battle field of the outdoor ground plane. Plan each cutting to chop back weeds before their seed heads can be produced, and plan each cutting so the tall weeds are damaged each time you mow. That will reduce the competition for the ground plane to just a few species—your turf grass and the short weeds that go to seed quickly. Reducing the competitions makes your fight for ground plane dominance much easier. The remaining weeds will be short varieties that won’t detract from the overall look of your ornamental landscape. Mow with an understanding of the limitations inherent in plants that typically germinate in healthy turf.
Mowable vs. Non-mowable Slopes
The slope ration of a turf field is a very big deal. If a slope is 3:1 or flatter, it is mowable. That means for every three feet of horizontal distance, a slope rises no more than one foot. You can easily measure this with a ruler and some string. You can determine slope ratio on a grading plan by the spacing between contours on a plan sheet. The slope ratio is a big deal for you as a landscape designer. You can use the line between mowable and non-mowable slopes to determine where the edges of bed lines should go on a project site. You can plant turf grass on slopes 3:1 or flatter, and ground covers. Slope ratio is a big deal for mowing contractors, too. A slope steeper than 3:1 is a dangerous hill for a tractor to traverse. A 3:1 slope boundary is a line between easily maintained turf and potential accidents.
The 3:1 boundary is a threshold for plant roots. If you attempt to grow turf grass on slopes steeper than 3:1, the roots will not hold the soil and the slope will not be very stable. When you are drawing your initial base map for a landscape plan, it helps to delineate the 3:1 slope break line to help you plan your design. You can plant ground covers or use mulch on slopes steeper than 3:1. If a slope gets any steeper than a 2:1 ratio, then it is too steep for even the most vigorous plants and trees. A 2:1 boundary is the threshold for any and all plant establishment.
If you mow lawns for a living, you will agree—it is a pain to mow around every single tree trunk. It takes a long time to maintain a site that is dotted randomly with trees. Professional landscape designers consolidate tree groves in natural areas with mulch or ground cover instead of turf grass on the ground. If you space trees no more than ten or fifteen feet on center, they will self-mulch with leaves each fall. Raking is reduced and mowing is made much easier if it can happen outside a large, consolidated tree area instead of between each individual tree.
When you are designing a site, keep trees together in groves and install a nice, deep edge between the mulched beds containing the trees and the lawn areas. Be sure to leave a strip of turf grass at least the width of a typical mower between mulched areas and the road to allow a mowing crew to mow the entire site without needing to hop into the roadway and back on to the grass.
Observe the areas where trees cast a shadow during the day, and include them in any consolidated, mulched bed. The shaded areas in a lawn are often bald spots in the turf. Eliminating them by making them part of a larger, mulched bed is a win-win. It is one less maintenance problem with which the mowing crew must battle.
The only place turf grass should be mowed lower than two inches is on a golf course green. During drought, mowing height should be raised to about four inches. This may seem like a simple thing to do, but it can get tricky when the ground plane has mounds and depressions. To maintain a level lawn, every spring broadcast a mixture of cow manure and sand on top of all depressions in the lawn, just enough to cover most, but not all of the existing grass blade length. Do this often, or at least every year until your lawn is a uniform height. Then, when you set mower blades for a two-inch cut, you avoid scalping the high points and missing the dimples. Your lawn will look much more refined.
For roadsides, the uneven ground surface is even more pronounced. There are lots of obstacles, litter, and stumps that large mower blades need to clear as they move in formation down the roadsides. Mowing can be dangerous for the adjacent traveling motorists, so mowing equipment for large public projects should have chains that hang down and deflect stray objects that might be flung into pedestrians or vehicles. The mowing height on roadsides can be somewhere between four and fifteen inches.
Mowing is time-intensive, labor-intensive, equipment-intensive, and a never-ending maintenance task for turf areas. Keeping grassed lawn areas to a minimum helps reduce the costs, but there are times when nothing but a carpet of green will do in an ornamental landscape. There are parts of the roadside which must be kept mowed for obstacle and erosion free safety. When mowing is required, design landscapes for smart mowing and efficient maintenance.