A rotary mower acts as a machete when it cuts through grass. If the blade is not kept very sharp it will rip your grass, not cut it. It's hard to tell unless you get down on your hands and knees, but your grass will not thank you for it. Ripped grass reduces the amount of stored nutrients and leaves your lawn susceptible to disease. Finally, having 4 wheels that are spread out wide increases the chances of scalping your grass. In a lawn that is not perfectly level one of those wheels is likely to find a divot and leave a swirl mark. 

The blades of a REEL mower act as scissors, cutting your grass smoothly and precisely. When your grass is cut cleanly by a reel mower it locks in the nutrients that help lead to a healthy lawn. Finally, having the wheels/REEL in a more compact area than a rotary, a REEL is less likely to scalp your lawn. Additionally, adding a front roller to you REEL will make it even less likely to cause scalping or swirl marks while cutting your grass.    

• Cuts like: Scissors, smooth and precise

• Leads to: smooth and healthy lawn

• General Cut Height: 1/4 - 2&1/4 inches (8+ heights)

• Cuts like: Machete, rips and tears

• Leads to: disease and unhealthy lawn

• General Cut Height: 1 - 4 inches (6-ish heights)