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One of the unfortunate truths in golf is that greens often shrink over time. Sometimes this is intentional, but in many cases it’s the product of inadvertent collar encroachment. As the greens mowers try to avoid scalping the collar, they allow it to creep into the green more and more. A tell-tale sign of this phenomenon on modern greens is the distance between the putting surface and irrigation heads used to water the green. Greens heads are often installed 3-6 feet from the putting surface during construction. If they’re farther than 6 feet from the edge of the green today, there’s a good chance the green is shrinking. I have seen greens at golf courses that lost 20%-30% of their area over time. When putting green surface is lost, so are hole locations and design intent, which usually means negative implications for playability and conditions.

Reestablishing lost square footage on putting greens can dramatically improve a golf course, but doing so can be much more complicated and time consuming than many people expect. Keeping collars from encroaching in the first place is much easier than trying to bring the greens back out after they have shrunk considerably. As the old adage goes: “An ounce of prevention is worth a pound of cure.” Consider these ideas to help you prevent collar encroachment and monitor for issues:

  1. Maintain a precise cleanup pass. Train all employees on the importance of maintaining original green size. Well-meaning employees often avoid the edge of the green when mowing cleanups to avoid scalping. This leads to collar encroachment.
  2. Edge the margin between the putting green and bermudagrass collars on a regular basis. This requires time, specific equipment, a steady hand and attention to detail. Delaying or avoiding this practice is a mistake.
  3. If putting greens are sand based and collars are built on native soil, core aerate the margin between the putting greens and collars to identify where the original boundary is. This can be done infrequently and is an easy way to identify the original construction size.
  4. Probe the soil to find the edge of the putting greens. Collars can easily encroach multiple feet in a short period of time so if things are bad enough, more intensive inspection may be required.
  5. If you think the greens at your course have shrunk considerably over time, you may need help from a golf course contractor to recapture the lost space. Planning and timing of this work is critical to long-term success.

Losing putting green area over time is a common problem. Unfortunately, the solution is not always simple. The best thing is to avoid this problem in the first place. If you think there is an issue with lost putting green area at your course, the USGA agronomist in your area will be happy to help you assess the problem and develop a solution before things get worse.

Southeast Region Agronomists:

Chris Hartwiger, director, USGA Course Consulting Service –

Jordan Booth, Ph.D., agronomist –

Information on the USGA’s Course Consulting Service

Contact the Green Section Staff