Most of us have performed the familiar task of mowing grass. Perhaps we view it as a boring chore, or maybe we actually enjoy the task of keeping the stripes straight and giving the turf a clean, crisp appearance. Although mowing seems like a simple enough task, there’s more to the picture than “making tall grass short!” Proper mowing is the most important practice to keep your field performing at its highest level.
Figure 1: Proper mowing practices go a long way to making your field the best it can be.
Sports field managers spend a lot of time mowing their fields- more time, in fact, than they spend on any other maintenance practice. In this edition of the Maintenance Minute, we’ll examine mowing more closely – how the grass responds to being cut, the benefits of mowing more often, and simple tips to maximize your time on the mower.
Let’s start by thinking about why we mow. As mentioned above, the most inherent reason is to keep the grass short, since it grows back after each mowing. This regrowth is fairly unique to grasses- most other plant species die if they are mowed over and over. In fact, frequent mowing at the correct height is THE BEST weed control method there is!
Our next point of discussion is cutting height. The height of cut is dictated by the sport being played- for example, shorter grass is needed for proper ball roll in baseball, but in football the grass can be taller since ball roll isn’t a concern. In Wisconsin, athletic fields should be mowed at heights between 1.5 and 3 inches. Taller grass has more leaf area to withstand the wear from field usage, while also shading the soil to conserve moisture and suppress weed growth. Tall grass also produces more roots, helping it to reach water deep in the soil during periods of drought. The diagram below shows the rooting depths of closely mown turf (left) and a taller turf (right).
Figure 2: Maintaining your field at a taller cutting height will help the turfgrass grow more roots and withstand the stresses imposed by drought and field usage.
While mowing the field is simple enough for us, the turfgrass plants actually have an elaborate response to this practice. Mowing produces chemical signals in the grass, alerting the stems to quickly replace what was lost. The plants accomplish this by growing new leaves, but more importantly by producing new lateral shoots called tillers. Tillers help the grass spread and fill in damaged areas. It’s a simple equation: the more often you mow, the denser your turf will be. A great example of this practice is on professional baseball fields, which tend to have very dense turf – in large part because they are mowed almost every day.
Figure 3: While professional baseball fields receive many inputs, near-daily mowing is among the most beneficial practices performed by these fields’ managers.
How frequently should you mow? It would be great to mow 4-5 times a week, but this just isn’t practical for most facilities. At the very least, follow the “1/3 rule:” Never remove more than 1/3 of the leaf tissue at a given time. For example, grass maintained at a 2 inch mowing height would need to be mowed as soon as it reaches 3 inches (preferably sooner). Mowing twice a week is a good starting point in order to follow this rule. Remember, the green leaf blades are a grass plant´s “food factory” so the more green tissue we remove, the more stressful it is to the grass. When most of the green is suddenly removed, the turf goes into shock. Root growth will stop within 24 hours and grass then puts all its energy into replacing the leaf tissue that was lost. It may take several days – or even weeks – for the roots to begin growing again. Weak roots lead to lesser tolerance for drought and other stresses.
Figure 4: Removing no more than a third of the leaf tissue when mowing produces a healthier turfgrass plant.
The three best ways to improve your mowing techniques are (1) choose the correct mowing height (2) mow more often, and (2) sharpen your blades more frequently. If you only mow your field once every 7-10 days, you will be amazed at how much better your grass will look by mowing 2-3 times per week! While this might be a scheduling challenge, try it for a couple months and you’ll be impressed with the results. The same goes for sharp blades- the whitish, frayed appearance of turf can usually be eliminated simply by running the blade over a file or a grinding wheel. Some turf managers sharpen their blades as often as every day.
Figure 5: Grass plants mowed with dull blades (left) and sharp blades (right).
Mowing is a time-consuming task, but its importance cannot be overstated! Mow frequently with sharp blades to maximize the quality of your turf. For more turf maintenance tips, stay tuned for future editions of the H&K Maintenance Minute, or contact Evan Mascitti at evan@HKSportsFields.com.