Reel vs. rotary

There’s a mower for every need and a need for every mower. There are two basic types, reel and rotary, but there are many species of grass and many turf management applications. Specialized jobs, such as golf course greens, require special mowers, but in general, all other jobs fall into the two broad categories. How do you know which mower to select and which criteria to use to select it?

That’s a good question for Jay Deputy, because he lives and works in Hawaii where there are many species of grass and a variety of lawn maintenance applications. He has a background in research, and is now an education specialist in landscape horticulture and turfgrass in the University of Hawaii’s Department of Tropical Plant and Soil Sciences. He’s been at the university for 35 years, and also has written about many issues that need to be addressed on the islands.

Photo by Ronald Matsuda.
Longtime University of Hawaii Education Specialist Jay Deputy says the selection of a reel mower or a rotary mower has pretty simple criteria, but beginners can be confused about which to purchase.

Deputy says that an operator should select a mower based on grass species and height of cut desired, but it isn’t that easy. There are five species of grass commonly used for horticultural purposes in Hawaii, with several varieties of some of those, and some uses cross over. There is a huge range of mowing heights, from 1/16 inch to 4 inches or even higher.

“The basic stipulation is mowing height,” Deputy says. “Anything cut to an inch or below will require a reel mower.” Grass heights above 1 inch may not be suitable for a reel mower and will require a rotary mower. Rotary mowers are generally not recommended below 1 inch, though some top-end rotary mowers can make a fine cut below that on flat turf­grass.

Of course, mowing height and grass species are inextricably intertwined, because each species has a desirable or recommended mowing height. Deputy’s brochure on turf mowing and other subjects ( provides a list of the prominent turfgrass species in the state and their recommended mowing heights. Bermudagrass, one of the most common, can be cut with either type of mower, depending on grass type or height desired.

Deputy says that most bermudagrass will be cut to less than an inch in height in either a sport setting or a high-end resort or residential setting, all of which are common in Hawaii. That calls for a reel mower, especially if one of the dwarf bermudagrass hybrids is being grown, and most lawn maintenance crews on those properties have good reel mowers. They may even be called upon to manicure some turfed areas down to 1/16 inch, and a reel mower is the only way to go in those situations.

They may also carry rotary mowers, because bermuda grown taller in some settings, such as property fringes or parks, will be cut to the more normal height of up to 1.5 inches. The other primary species cut to those taller heights are St. Augustinegrass and buffalograss. The former can often be maintained at 3.5 inches, and the latter almost as high. A reel mower would be bogged down in that, and with rotary mowers cutting so much faster, they would be the mower of choice. St. Augustine, in particular, has a thick thatch, Deputy points out, and a reel mower just couldn’t cut down through its thick leaves and stolons without risking misalignment of its blades.

Photo courtesy of Seago International. Photo by Jay Deputy.
The Hayter Harrier rotary mower. A reel mower has more maintenance needs and costs more, but it delivers a finer, closer cut.

The other main species grown in Hawaii is zoysiagrass, in several cultivars or types, and it is maintained from .5 inch to 1 inch depending on the type. Thus, zoysia is almost always utilized in a manicured setting and cut with a reel mower. Some emerging hybrids, like Emerald, Deputy says, especially need reel mower attention. Zoysiagrass cut with a rotary mower can look puffy and thatchy after a while because it takes a reel mower to keep them growing low. The El Toro improved selection of zoysiagrass is becoming very popular in Hawaii, he points out, and it is a wider-bladed grass that can be left to grow to 1.5 inches in height and cut with a rotary mower in those instances.

Seashore paspalum can be cut with either a reel or rotary mower, Deputy says, but in their primary uses in Hawaii they are grown to less than 1 inch in height and therefore need the reel treatment. The species can tend to mound up if cut with a rotary mower, which leads to scalping as the mounds build. Anytime seashore paspalum is cut with a rotary mower there is a risk that thatch buildup can jeopardize the stand.

“It will get thicker and thicker,” Deputy says of paspalum that isn’t cut low. This can result in poor-quality turf­grass, whereas St. Augustine’s rough leaves like a tall stature, and the stolon buildup will have to be accommodated. “That’s absolutely the grass that cannot be cut with a reel mower,” he says of St. Augustine. Paspalum needs the reels, and it takes some time to learn how to mow it because of its tendency to grow fast, accumulate thatch and be susceptible to herbicide damage.

Deputy, who also writes an occasional horticulture column for the Honolulu Advertiser, emphasizes that all grasses grown in Hawaii are warm-season and he can’t make recommendations on cool-season species. Having grown up in the Midwest, though, he says that most cool-season species other than bentgrass are grown at over 1 inch in height and cut with a rotary mower, except in sports settings.

A big part of the mower selection process for a lawn maintenance company would be dependent on the turf management. Deputy says that the company could discuss a turf management strategy with the property owner to help determine the purpose and setting of the grass. That will let both parties know what to expect from the mowing process as far as height and quality of cut, and help the company make sure it has the proper mower for the job. Some upscale properties in Hawaii, such as resorts, have more than one type of grass and necessitate bringing both types of mowers to the site.

Properties with large expanses of turf usually demand more quality mowing, which calls for a reel mower, even though a rotary mower will cut more square feet per hour. A reel mower just doesn’t maneuver as well around trees and other obstacles, and isn’t designed to cut backward. Also, as the cut gets finer, the time required to mow grows longer. A mowing operator should take these factors into consideration in order to plan for mower life, mowing schedule and pricing of each job.

Turf management is also important in gauging irrigation and fertility programs so that grass growth can be properly timed and coordinated with mowing. In general, seashore paspalum may need to be cut every four days or so, while in some cases, St. August­ine can be left for two weeks. This can change with variations in the application of water and fertilizer (or weather). In general, both for the health of the grass and the difficulty of mowing, no more than a third of the height of the grass should be removed in a mowing.

When choosing a mower, an operator should also keep in mind other factors, such as cost. Deputy says that in general a reel mower is going to cost much more than a rotary mower. Reel mowers also vary widely in cost based on the number of blades they feature, with a 13-blade reel cutting much more finely than a seven blade reel mower, and also costing more. Besides owning both types of mowers, some operators must also buy both fine-cutting and rough-cutting reels.

Maintenance is also an issue. Reel mowers are more difficult to maintain because they are harder to keep in alignment. It is also more expensive to sharpen the blades, and companies with a mechanic and equipment shop have an advantage in cutting costs of maintenance on reel mowers. To avoid damage to mowers and the grass, Deputy would like to see operators adjust their mowing heights more often as jobs change. It is easy to do and can avoid scalping or the time-consuming adjustments of reel mowers as they lose alignment in tall grass.

“It’s much more difficult [to adjust alignment] on a reel mower, and it’s much more important on a reel mower,” Deputy says. With the purchase of any reel mower, good alignment should be planned as part of the long-term cost of the machine in order to avoid uneven cuts.

Height of cut is the defining criterion of which type of mower to select, but there are many other factors that must be taken into consideration.

Don Dale is a freelance writer and a frequent contributor. He resides in Altadena, Calif.