COURSE CARE
The How And Why Of Vertical Mowing Greens May 1, 2013 By Pat Gross

The close-up in the upper left portion of this picture shows the vertical mowing blades that slice into the turf. The close-up in the upper right portion of this picture shows the approximate depth of the cut. The main body of the image depicts what the putting surface looks like after it has been vertically mowed, or as it is sometimes referred to as “verticut.”

A question from a committee member during a recent Turf Advisory Service visit prompted a lengthy discussion. The question: why is vertical mowing done on greens, and how often should it be done?

Vertical mowing is a maintenance practice periodically performed on greens to accomplish the following objectives:

  • Remove excessive leaf growth that contributes to puffy, spongy surface conditions.
  • Improve mowing quality and surface smoothness.
  • Cut laterally growing stolons and promote an upright growth habit.
  • Open grooves in the turf canopy for the incorporation of sand topdressing.
  • Dislodge and remove Poa annua seedheads.

The process involves using a putting green mower fitted with thin, tightly spaced blades that cut vertically into the turf. The depth of the blades is typically adjusted 1/64-inch to 1/8-inch below the effective cutting height so that the blades penetrate the turf canopy. The goal is to thin the turf canopy while maintaining a proper balance of leaf growth and turf density.

There is no standard recommendation for the frequency of vertical mowing. It is a judgment call made by the superintendent based on the condition and growth rate of the grass at any given time. Poa annua and creeping bentgrass greens tend to grow more rapidly during the spring and fall, while bermudagrass is more aggressive in the summer. During these times, vertical mowing is often performed every one to two weeks. Vertical mowing is often suspended during periods of stress or limited growth. Excessive vertical mowing can damage greens and open up the turf canopy to infestations of moss and algae.

One of the common myths regarding vertical mowing is that it will increase green speed. Actually, green speeds are typically slower for one to two days following the operation and then return to normal.

Like many golf course maintenance practices, there are a wide range of techniques and equipment for vertical mowing greens. The method, equipment and the frequency of vertical mowing is best determined by the experience and judgment of the superintendent based on the prevailing course conditions.

We would like to remind all TAS subscribers that the deadline is approaching for the discounted TAS fees. To receive the $500 discount, payment must be received by May 15, 2013.

Source: Pat Gross (pgross@usga.org)

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