Vertical mowers for large areas
The aggressive growth of turfgrasses such as bermudagrass, Kentucky bluegrass, zoysiagrass and creeping bentgrass leads to the production of a heavy thatch layer. Periodic vertical mowing helps keep thatch from becoming too thick.
Vertical mowing, or verticutting, describes using a machine equipped with blades that reach vertically into the turf canopy to cut through lateral stems and dislodge thatch. You can adjust the blade height of most units to control how deeply you cut into the turf and how much thatch you remove.
The shape and length of the blades, and the spacing between them, vary depending on the type of unit and its manufacturer. A vertical mower is a machine with solid-mounted blades on an axle. Dethatchers or power rakes, by contrast, have blades or wire tines connected to the axle with springs or as flails to allow some movement in response to striking a hard object. However, both are frequently used to dethatch turf.
How often should you take steps to control thatch? That varies with the use and type of turf and the intensity of fertilization and irrigation. A residential property in a northern climate with a comprehensive fertilization program and an automatic sprinkler system might require vertical mowing once every other year. The same basic program on a high-visibility commercial property with an aggressive turfgrass species might require vertical mowing each year. Heavily used turf with year-round activity and a higher level of fertilization could require vertical mowing two or more times each year.
What's the best gauge of when it's time to vertical mow? Simply check the thatch depth. For most purposes, 0.5-inch or less of thatch is acceptable, while heavier thatch can lead to numerous turf problems.
Fitting vertical mowing into turf maintenance Vertical mowing during active turf growth periods speeds turf recovery. Therefore, you can achieve the best response with warm-season grasses by verticutting in late spring or early summer. The optimum timing for cool-season grasses is early spring or late summer/early fall.
Aggressive vertical mowing will create more surface disruption and require a longer recuperative period. You must consider the aesthetic and practical aspects of surface disruption to determine the best timing. For example, you might schedule vertical mowing of cool-season turf on an elementary school playground at the start of spring break, while a home lawn play area might be better scheduled after school has started in the fall.
Verticutting can stimulate development and hasten the fill-in process of young stoloniferous turf by severing the stolons, which encourages rooting at the nodes. When you require rapid establishment, such as in high-use areas like parks, athletic fields or golf courses, you can verticut as often as every 5 to 10 days.
Vertical mowing in two or more directions helps prepare established turf for overseeding. Similar aggressive verticutting helps transition out cool-season grasses over-seeded on warm-season turf. Timing of the process is critical in both the transition-in and the transition-out in this type of over-seeding to take advantage of temperatures favorable to the turfgrass you're trying to promote.
For example, during the transitioning-out of perennial ryegrass overseeded into a bermudagrass base, vertical mowing thins out the perennial ryegrass and allows greater light penetration to help stimulate bermudagrass green-up. If you waited until the bermudagrass began active growth, aggressive verticutting could force the plants to channel resources to root development, which would weaken its competitive edge over the perennial ryegrass.
For less aggressive verticutting, you can add turf-conditioner attachments to greens mowers, mounted ahead of the reels, to make slight vertical cuts through the turf prior to the mower passing over it. Conditioners are effective in reducing the grain of the turf. On a golf green, the conditioning cuts increase greens speed without reducing the height of cut. On athletic fields, they reduce or eliminate the erratic ball roll called "snaking." For more aggressive verticutting during overseeding or the transitioning-out of overseeded grasses, greens mowers can be equipped with vertical cutting units.
Making the match Equipment selection depends on the type and size of the turf area and the labor and budget resources available. You may need several units to match different needs.
Some triplex reel mowers can be equipped with vertical-cutting attachments. This can be a good choice for high-profile sites when several machines already are part of the equipment package and the areas to be covered are level and open, such as athletic fields. Heavily landscaped or undulating sites such as segments of some golf courses, corporate, municipal or school properties, or apartment or condominium complexes are also suitable for these attachements. Multiple machines operated by the regular mowing crew can cover large areas during overseeding and the transitioning out process.
Large, open, fairly level areas allow greater flexibility in equipment selection. Some self-propelled, five-plex fairway mowers accept vertical cutting attachments. This puts the width of each verticut pass in the 100-inch range. Hydraulic gang mowers in the five- or seven-gang configuration can be similarly equipped for even greater coverage. Tractors need a minimum of 25 PTO horsepower for most five-gang systems. Mowing width may increase to 10 or 11 feet with a five-gang configuration and as much as 15 feet with a seven-gang unit.
Many dedicated aerator units offer vertical-mowing options as well as solid- and open-tine aeration. You replace the tines with blades to verticut, then go back to the desired tine configuration when you want to aerate. A few such units are available for front-mount mowers. More are available as either pull-behind or 3-point hitch-mounted units. For these units, the width of coverage per pass ranges from 4 to 12 feet, depending on the manufacturer and model.
Tine-type, single-purpose dethatchers are available as pull-behind units or as attachments for front-mount mowers. These range from 42 to 60 inches in width of pass.
Debris removal Large-area, aggressive vertical mowing produces masses of thatch debris that you must remove quickly for the sake of turf health as well as aesthetics. Collection or vacuum systems are available to handle the job.
* Mechanical collection systems can be towed behind compact tractors or heavy-duty utility vehicles. Rollers or brushes at the front of the unit adjust to different heights for optimum pick-up with minimal turf wear. Most have a swath width of about 4 feet and a hopper capacity of 20 to 30 cubic feet. Hoppers generally are enclosed to trap the thatch and to control the dust that is an inevitable part of the vertical mowing and collection process. Some units offer hydraulic-powered dumping ability as well.
* Vacuum systems may by PTO-driven or self-powered. A 30-hp tractor is the minimum requirement for a vacuum system with a 40- to 50-inch swath. Heavy-duty impeller fans power the suction nozzles that move material into the hopper. The hoppers may be enclosed or include a dust reduction tarp. Hydraulic tilt improves dumping ability. A separate, hand-held hose attachment is optional on some units for collection of debris in hard-to-reach areas.
On self-powered units, a 20-hp engine should provide sufficient power for a vacuum unit with a 5-foot swath. Some units are equipped with rotating brushes or rubber appendages to help lift debris out of the turf and into the vacuum. Enclosed systems trap debris and dust.
Both the collection and vacuum systems allow a single operator to handle the pick-up and dumping aspects of debris collection. Both types are useful for cleanup of many other types of debris.
Verticut plus Several units provide verticutting in conjunction with other procedures. For example, some units slice through the turf into the soil and then drop seed, all in a single pass. Some of these units also are equipped with attachments that keep the slices open until the seed is dropped into place.
Other units verticut or dethatch and then sweep up the debris during a single pass. Some offer options in blade shape to match the degree of thatch removal. Production varies with the type of turfgrass, turf density and level of thatch build-up, but averages between 2 and 3 acres per hour.
Finding the right machine The first step in equipment selection is analysis of your vertical-mowing needs: amount of area to be covered, the number of times the equipment will be used during the year and the timing of use. Other points to consider: other uses of the unit and of the vehicle you'll use to tow or power that unit; set-up time (if you must install the unit on another machine, such as a mower); and labor and budget resources. The variety of available units can satisfy virtually every verticutting need.
Bob Tracinski is the business communications manager for the Worldwide Commercial & Consumer Equipment Division of John Deere (Raleigh, N.C.).
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