The stripes are actually a product of sunlight reflecting off the grass blades: Blades bent toward you look darker, while those bent away look lighter. The blades bend in opposite directions as the rear rollers of a mower deck travel back and forth across the lawn.

Is lawn striping bad for grass?

The real value in striping, says Mangan, is that it encourages healthy grass growth. Mowing in one direction too often can actually cause the taller grass to bend over and shield the grass below from the sun, which over time could kill it.

Is a striping kit worth it?

Using a Striping Kit for Your Mower

You don't need a striping kit necessarily and will get some effects just from the safety strip at the rear of a standard mower but investing in one will makes your lines crisper and clearer.