Think of golf course aeration as preventive maintenance: It's the (typically) annual process of punching little holes into greens (and sometimes fairways) that opens up growing room for grass roots and helps keep the turfgrass healthy. (It's also called "aerification.")
The Aeration Process
To aerify a golf green a piece of machinery built for the task cores the ground (punches holes and removes the dirt) in a certain pattern. (The small cores of dirt that are removed are called "plugs.") Air and water are thus infused into the ground at root level, and space opened up for new root growth.
The holes left behind are filled with sand in a process called "topdressing." Once topdressed, a course is said to have "sanded greens."
The greens are left alone for a few days (although golfers may still play them) and the grass allowed to grow. The topdressing gradually disappears as watering takes place.
The actual coring of the greens is a quick process, but from the time of the coring until the greens are somewhat back to normal is about a weeklong process. Signs of the aeration holes may remain on the putting greens for longer after that.
The Benefits of Aeration
The bottom line on why golf courses go through the process of aerified greens is that over time it keeps the greens healthier. This is the case because:
- Aeration loosens soil that has been compacted by golfers walking over it and machines rolling over it.
- This opens up growing room for the roots and increases oxygen to the roots.
- The roots of the turfgrass thus can grow deeper, creating a healthier putting surface.
For a more in-depth look at the golf course aeration process, see the article "Aerification Is a Necessary and Highly Beneficial Golf Course Practice."
What About Those Aeration Holes: Do You Get Relief?
Those pesky aeration holes may be around for a couple weeks. They are quite annoying at first but still noticeable and perhaps distracting for another week or two after that.
If your golf ball comes to rest on an aeration hole, what's the ruling? Do you have to putt it like that? The answer is a qualified yes, with an exception possibly provided through a local rule.
Aeration holes do not qualify as an abnormal ground condition, because the governing bodies specifically say they do not qualify as "ground under repair" in Decision 25/15:
"Q. Is an aeration hole a hole made by a greenkeeper within the meaning of that term in the Definition of 'Ground Under Repair'?
So, no relief from aeration holes unless … unless the Committee in charge of your course or competition has adopted Specimen Local Rule 3c that appears in Part B of Appendix I to the Rules of Golf. The most to-the-point part of that local rule is this: "On the putting green, a ball that comes to rest in or on an aeration hole may be placed at the nearest spot not nearer the hole that avoids the situation."
Because such a local rule would be of limited duration, it would not be printed on the scorecard. If it is in effect, it should be posted on a notice board for all to see before beginning their round.
So, do you get free relief from aeration holes on the putting green? No, unless the local rule cited above is in effect.
Note that some golf courses use temporary greens during aeration. Some may also offer reduced greens fees during the aeration period.