Blades of glory
At Fenway, the grass isn't just greener. Its design is ever-changing.
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Grass blades that are bent away from your vantage point (for our purposes, we'll say away from home plate) catch more light and thus appear lighter in color. Grass blades that are bent toward your vantage point don't catch as much light and thus appear darker in color. Bend some of the grass one way and some of the grass another and you've created a pattern. That's it.
While Mellor and his staff mow the field every game day, cutting isn't how they work their magic. Instead, they literally roll out each new design, using either hand-pushed rollers (some weighing 75 pounds) or large, metal rollers affixed to their riding mowers that flatten the grass as they drive over it.
Even something as simple as a garden hose, given sufficient pressure and the right nozzle, can be used to bend grass into an eye-catching design, Mellor says.
"I've seen people do smile faces, birthday cakes. I've had kids on my crew who used a hose and a squeegee to write 'class of 2007' on their grass. I think anything is possible, other than the Yankee logo," he said, cracking a smile.
http://www.boston.com/news/local/articles/2007/09/16/blades_of_glory/