A Dummies Guide to Mowing

It's easy right? Just fill 'er up with gas and cut that grass! Mowing does not exactly seem like a science, and except for your dad telling you to overlap your mowing rows so as not to leave any stragglers behind, not much instruction is passed on from one generation to the next when it comes to mowing. Here are a few tips that our dads may or may not have left out of our lawn mowing initiation.

Selecting a Mower Type
The two primary types of mower on the market are rotary mowers and reel mowers. The rotary mower certainly wins out in the residential market whereas gasoline powered reel mowers are more widely used in professional settings like athletic fields and golf courses. Besides the method of cutting, the primary difference between the two mower types is the quality of cut, with the higher quality going to reel mowers. Even though reel mowers provide a higher quality of cut they require more maintenance and are harder to adjust which is why they are typically left to the professionals. If there is a mixture of weeds in the grass, the reel mower may have some trouble cutting them if they get too tall. For typical home use, I would recommend purchasing a rotary mower.                              

Mowing Height
Why does mowing height even matter? When we mow, it is like cutting off a plants head or arm or leg, or however else you want to look at it. The bottom line is that we are removing a part of the plant that was originally useful to it and we are essentially injuring it. The portion of the grass blade that is removed is a loss in photosynthetic potential as well as stored carbohydrates for the plant. This reduction in photosynthetic potential and carbohydrates consequently affects the root growth below ground. Taller grass equals a larger root system. Shorter grass equals a smaller shallower root system. This becomes very important when it comes to water availability in the soil, especially during drought conditions. The deeper the roots can go, the more water they will have available to them. the grass also serves to shade the soil, this shading affect reduces weed seed germination. Therefore if grass is cut too short it could encourage weed growth because of reduced shading. And as can be seen in the table below, some grasses simply have a preferred height of cut based on field research. 

Table 1. Recommended Mowing Heights for Lawn Grasses
Turfgrass	Cutting Height in Inches	Mowing Frequency
Cool-season
Kentucky bluegrass	Winter: 1.5 to 2.5	High
	Summer: 2.5 to 3
Fine fescue	Winter: 1.5 to 2.5	High
	Summer: 2.5 to 3
Tall fescue	Winter: 2 to 3	High
	Summer: 3 to 3.5
Ryegrass	Winter: 1 to 2.5	Medium
Warm-season
Common bermudagrass	1 to 2	Medium High
Hybrid bermudagrass	0.5 to 1.5	Very High
Carpetgrass	1.5 to 2	Low
Centipedegrass	1.5 to 2	Low
St. Augustinegrass	2.5 to 4	Medium to High
Zoysiagrass	1 to 2	Low to Medium

Source: Clemson Cooperative Extension: Mowing Lawns
Mowing Frequency

A general rule when it comes to mowing frequency is to only remove 1/3 of the leaf blade when mowing. For example if the grass is 3" tall you should only mow it to 2" tall, removing 1" of the grass blade. You can also calculate this in reverse order. If you have St. Augustine grass and you want to maintain it at 4" tall you should cut it when it reaches 6" tall in order to remove only 1/3 of the leaf blade. Following this rule will minimize stress on the grass. In reality are you going to go out with a tape measure to the grass? No. But this is a useful principle that can be determined pretty accurately with the eyeball test.

Mulching Vs. Bagging
It is easy to think that because the lawnmower comes with a mulch bag that it is proper procedure to collect the leaf clippings while mowing. This however is incorrect. By mulching (allowing the grass clippings to return to the soil) the nutrients from the leaf clippings are recycled back into the soil and taken up again by the grass. The only scenario that I would advise collecting leaf clippings is if the 1/3 rule mentioned above has not been followed and you are getting a significant buildup of clippings on top of the grass. This buildup can kill the grass underneath it if significant enough. Either bag the clippings while mowing or come back afterwards and use a rake or blower to spread them out.
Blade Maintenance
The lawnmower blade should be sharpened every spring and possibly more often depending on how much use it gets. A sharp blade produces a cleaner cut of grass that will not fray and turn brown at the tips.

Final Odds and Ends to Consider

It is best to cut grass when it is dry. This will reduce the amount of clumping of grass clippings and clogging of the mower. Try to avoid scalping the grass which often happens on uneven ground. Scalping is when the mower blade gouges into the grass, cutting one section very short or even into the soil. Final instructions: have fun! Mowing is a blast!