Strategies for setting mowing heights and frequencies
In Oakland, Calif., Martin Matarrese, mowing and irrigation supervisor with the city’s park and building services division, oversees the care of approximately 300 acres of irrigated, manicured turf. With some 134 parks and public grounds in Oakland, each member of the five-person mowing crew has up to 37 stops to make on their routes. “We’re in tough economic times. We have fewer people mowing, so each staff person has more acreage than they did, say, five years ago,” he explains. Each crew member now has about 50 acres to mow. Each travels with a large-area mower (Toro 580D, John Deere 1600 and a pull-behind Land Pride flex mower) and a trimmer mower (John Deere 1400), and it can take up to three weeks for each to mow all of their areas and then start over again.
Recent layoffs in the department have, in some cases, increased the interval between mowings at Oakland parks. “Our mowing frequency varies between one week and three weeks, depending upon the use of the turf area,” explains Matarrese. “We try to mow our sports fields, particularly baseball, and especially during the season, more frequently. They take priority to a general park area or a median.” The ball fields are typically mowed at about 2.5 inches, with some bermudagrass infields mowed even lower than that.
In the winter, the weather in Oakland is wetter, and this sometimes affects how often the grass can be mowed. “During that time of year we mow fairly high, up to 4 inches, so that we don’t leave a lot of clippings and thatch behind,” says Matarrese. “During the summer, we go down to about 3 inches for water conservation purposes.”
Apart from the sports fields, Matarrese describes the grass in many areas of the Oakland parks as “sort of a mongrel mix.” With species ranging from ryegrass to bluegrass, as well as Kikuyu, bermuda and clover (there are no broadleaf herbicides applied in the parks), each growing at a different rate, mowing to achieve a consistent appearance is a challenge. “The broadleafs usually shoot up higher than everything else, and the public likes it when everything looks even,” he says.
Complaints relating to turf usually come if the height of the different grasses growing is uneven, or if there is a lot of clippings/thatch present, he adds. The most challenging time of year to keep everything mowed to an appropriate height is spring, he adds. “Everything is growing really fast here in April. There’s a lot of ground moisture and sunlight, so everything really takes off.”
Across the country in York, Maine, the parks and recreation department mows general park areas at 3 inches or above, and athletic fields at 2 to 2.5 inches. Those heights, he says, have been determined based mainly on years of trial and error, according to Ryan Coite, foreman. “We look primarily at the health of the grass. Three inches seems to be a good height in parks settings, even if we get a drought, it doesn’t seem to affect that grass very much if it’s kept at that height. The shorter you cut grass, the better it looks, but if you get into a drought, the grass is going to burn up,” he says.
Cutting at 3 inches also seems to work well from a practical standpoint. “We get a lot of turnover; usually there are three or four new guys mowing every year. Obviously, the lower you’re mowing, the easier it is hit rocks and things like that,” Coite says. Keeping the cut a little higher gives the new employees a chance to learn where the hazards are without destroying blades or damaging mowers.
The York parks maintenance staff uses an assortment of rotary mowers. “We really don’t have two that are the same,” says Coite. “We have some that pick up the grass clippings and others that don’t.”
Coite says that the sports fields are the exception to the 3-inch rule, as the grass needs to be kept shorter to ensure proper performance. Even then, there are limits to how low they can be mowed. “Two inches is pushing it with a rotary mower; at that height you’re prone to scalping some spots if they’re uneven. Usually, we try for closer to 2.25 inches, or 2.5 inches is a better height for soccer. The field hockey people would like to see their fields even shorter, but we really can’t.”
Mike Woodward, horticulture manager with the Boise, Idaho, parks and recreation department, says the grass there is maintained at between 2.5 and 3 inches. “On some of our right-of-way sites, where there is no foot traffic, we’ll mow closer to 4 inches, especially where there’s fescue,” Woodward adds.
“Several years ago, we tried to start mowing a little shorter in the beginning, and then mowed a little longer in the heat of the summer, and then dropped back down to a shorter height in the fall, but the time it took to get the mower heights all adjusted up and down just proved to be a nightmare,” says Woodward. “We do accommodate the soccer people at one park by mowing the grass shorter, as low as 1.75 inches, but that is something that’s outside of our standard maintenance practices, so we charge them extra for that.”
Boise uses a combination of Toro, Jacobsen, New Holland and Hustler mowers, some as large as 111 inches and most bigger than standard zero-turns. One mower is set up specifically for the low height required on the soccer field, another is set up specifically for the longer heights maintained on rights of way. The rest of the mowers are adjusted for general park use, and heights are rarely adjusted. “It’s just too difficult, especially with the larger mowers, to change the mowing heights with any kind of frequency,” Woodward explains.
There are more than 1,000 acres to maintain in Boise’s parks, with a mowing crew of 15 to 20. “All of our mower operators are seasonal employees, so our mechanics take care of making any adjustments needed. Otherwise, we’d have 10 different mowers mowing at 10 different heights.”
Most of the park turf areas are made up of a bluegrass/ryegrass mix. In most cases, the grass is mowed at seven-day intervals. “If we went to a 10-day cycle, we’d start running into weekends, but keeping it at seven days allows us—except during the spring flush of growth—to avoid having any problems with excess clippings left behind, because we put all of the clippings back on the grass,” Woodward says.
At times, the department hears complaints from user groups that the grass is too long. In such cases, they try to educate the public that they are saving water and reducing costs by spreading out mowing frequency, he says.
One way the Boise parks department has found to cut down on costs is to, whenever possible, mow athletic fields and park areas that tend to grow quickly as late in the week as possible, so the grass is short for busy weekend events. “We do that as much as we can without causing a lot of routing problems. We don’t want to drive 13 miles across town just to mow one field,” says Woodward. This scheduling approach gives the turf its best appearance when the most people are using it without having to actually increasing the frequency of mowings.
Some city parks departments have decided to increase the intervals between mowings as a way to save money in a time of tight budgets. The result has undoubtedly led to some grumbling by user groups at those parks. Sometimes the reaction has been even more negative. Last year, in Sandusky, Ohio, a frustrated resident was actually arrested for mowing a city park that had become overgrown. “The other day when I went by, I took a look at it and measured it. It (was) a foot tall,” John Hamilton told the local newspaper after he was spotted by parks staff on his lawn tractor and arrested by police for obstruction and disorderly conduct after he refused to stop. “At the scene, Sandusky police Officer John Powell measured the grass and it was indeed more than 1 foot high,” reported the Sandusky Register. The city cited staffing cutbacks for the neglected park lawns.
In Baltimore, the city parks department has taken a more thoughtful approach by establishing “mowing standards” to ensure that the turf is mowed in the most efficient way possible. “Mowing heights are now set at 2.5 inches,” explained recreation and parks department director Wanda Durden last year when presenting the department’s budget to the city council. Durden pointed out that the height was selected as it “allows the grass to grow a full inch before additional mowings are required. The additional growth also promotes a healthy turf and we save resources, as fewer mowings are necessary to maintain the standard.”
In Manhattan, Kan., Parks Superintendent Eddie Eastes says that increasing the time interval between mowings has been discussed as a possible budget-saving move within the city’s parks and recreation department. “We’ve had that discussion. We haven’t started it yet, but it is a potential cost-cutting measure that we could take. We’re not at that point yet, we’re trying to avoid that and hold out for now.” With 21 parks totaling more than 1,000 acres in Manhattan, even small changes could have a big impact.
Eastes says that irrigated areas with cool-season grasses (mostly a turf-type fescue) currently are mowed at 3 inches. Keeping the grass a bit taller in nonirrigated areas also seems to work well, he adds. “We don’t put out any preemergents in our nonirrigated areas, so we’re hoping to help shade out the crabgrass a little, which is a common summertime issue.”
More specialized sports areas are mowed a little lower than 3 inches. The sports fields also receive more frequent mowings, a minimum of two times per week and oftentimes three mowings each week. “It just depends what type of growth cycle we’re in at any given time,” he adds. General park areas are mowed at least once a week, and sometimes twice per week.
The maintenance staff tries to avoid changing the heights on the mowers it uses. Instead, mowers are locked in to the appropriate heights and dedicated to specific areas, whether sports fields or general park areas. “We try to keep the same mowers on the same areas,” Eastes explains. He also subscribes to the theory that it’s best to mow high-use, high-profile areas as close to the weekend as possible. “People really notice it when they’re here on the weekend or playing in a weekend sports tournament and the grass was mowed early in the week. People do take note of the mowing.”
Patrick White is a freelance writer and editor who has covered every aspect of the green industry in the past 13 years. He is based in Middlesex, Vt.