How do they make those crazy designs on major league baseball outfields?

October 22, 2018 – Does baseball have you seeing stripes, diamonds, and circles? The Oct. 22nd Sustainable, Secure Food blog explains the turf maintenance and mowing practices that make baseball infields and outfields a visual feast.

The light and dark green shadings on turf are the result of bending grass in different directions during the mowing process. “Mowers that make the best mowing pattern will have a solid roller that helps bend the grass. Laying turfgrass in different directions determines how the light will reflect off of it. Turfgrass blades laying towards you look dark. Those laying away from you look lighter in color,” explains Adam Thoms, Iowa State University.

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The home lawn enthusiast may be surprised to find the variety of equipment available to professional turf teams:

  • A solid roller will help bend the grass in broad designs.
  • Brooms can create intricate designs.
  • Blasts of water can lay the grass down for detail.
  • Streams of air, controlled by software, can create patterns in both directions at once.

Additionally, there are practical matters to consider, such as clear foul lines. “The mowing pattern of cool-season turfgrasses should always be parallel to the lines painted on the field to avoid the lines appearing wavy,” Thoms says. “Some mowers now have global positioning systems (GPS) on them to help with creating these mowing patterns and to make sure the lines they are producing are straight.”

As you tune into the World Series, you may see some interesting designs in the baseball outfield. Or, perhaps you have seen the dark and light pattern of turfgrass on football fields this fall. You won’t see any patterns on soccer fields – as they have been found to impact the roll of the ball. Thus, soccer fields have uniform mowing. But, baseball field managers take pride in the aesthetics that patterned turf adds for those in the stands (and watching on the television).

This patterned look is not created by planting two different turfgrasses. They are created by laying the turfgrass in various directions. Often these are called mowing patterns. The type of grass on the field may influence how well you see the patterns, as well as other factors.

Grasses that are mowed at a taller height show patterns better. This higher height of cut will show more contrast of light when laid in different directions than a shorter height of cut turfgrass.

Cool-season grasses like Kentucky bluegrass and perennial ryegrass are two types of grasses that are mowed high (usually 1.5-3 inches). Bermudagrass is a more aggressive grass, and it can be maintained at a lower height. In addition, this warm-season grass needs a boost with ryegrass early and late in the season. On these fields you may not notice a mowing pattern mid-season, when the field is just bermudagrass. Once the grounds crew adds the boost of perennial ryegrass, you can see a mowing pattern.

Mowers that make the best mowing pattern will have a solid roller that helps bend the grass. Laying turfgrass in different directions determines how the light will reflect off of it. Turfgrass blades laying towards you look dark. Those laying away from you look lighter in color.

For higher height of cut turfgrasses, the mowing pattern may be limited, because laying the grass one direction and then another can make a line look crooked. An example of this would be on a football field or foul line on a baseball field. The mowing pattern of cool-season turfgrasses should always be parallel to the lines painted on the field to avoid the lines appearing wavy. Some mowers now have global positioning systems (GPS) on them to help with creating these mowing patterns and to make sure the lines they are producing are straight.

Intricate designs and details are often done with brooms helping to create details in the pattern by laying the grass in different directions. Some baseball fields will use blasts of water to lay the grass over as well to help with intricate patterns. Typically these need to be done every day to ensure the grass is laying the correct direction.

One company has a new technology using GPS. Their machine uses global positioning or GPS technology to create intricate patterns with controlled streams of air delivered through a roller to help lay the turfgrass in various directions. They can even print logos or other patterns on the field. A specific type of roller is set under a tractor set up for straight lines and then a laser is on top of the machine to help mow the correct pattern. Software will help control the air-blasts so that a pattern can be made in both directions which will speed up the mowing pattern. Older technology required the mower to only be able to create a pattern from one direction, drastically adding time to mowing a field.

Mowing patterns can be changed by laying the turfgrass in a different direction, foot traffic standing the turfgrass upright or trampling it in the opposite direction, and by turfgrass growth slowly standing the plant back upright.

Most patterns you see at sporting events have been mowed the same direction for multiple days to ensure the turfgrass leaf blades are laying in the correct direction for maximum viewing pleasure. Repeated mowing in the same direction will cause some of the turfgrass blades to not be mowed due to the angle of the blades, and also the mower wheels are always compacting the same areas on the field. That is why it is good to change directions of mowing after every mowing, or at least after a big event to remove the pattern.

So next time you are watching an event, you can answer the person sitting next to you on how they made that design on the field.

Answered by Adam Thoms, Iowa State University