[PHOTO: Glyn Kirk]

It might approaching winter in Australia, but it’s a question that lingers for many golfers during all parts of the year – because it seems to happen each year: just as they reach their peak and the greens are starting to roll well, they get cored.

The ensuing days and weeks are the most frustrating of the year. Surely there must be a reason why our golf course superintendents wait until the greens are in good shape to aerate, right?

Coring greens, as explained by a top course superintendent

That’s the question I asked Mike Dachowski, the superintendent at Shelter Harbor Golf Club, an exclusive private club in Charlestown, Rhode Island, ranked on our latest America’s Second 100 Greatest Courses list. Under Dachowski’s leadership, the course is among the top-conditioned courses in the New England region of the USA, according the Golf Digest ranking panel.

Shelter Harbor Golf Club
Shelter Harbor Golf Club in Charlestown, Rhode Island.

Golf Digest: Mike, many of the courses I play start to roll really well by mid to late spring, but then all of a sudden they are aerated. Is that timing intentional?

Mike Dachowski: Yes, the timing of aeration is very important. If you aerate before the grass wakes up and reaches an appropriate growth potential, then the grass isn’t going to heal. It might take weeks for aeration holes to fill in because the grass just isn’t growing.

That’s why we aerate a few weeks into the [spring] and not right at the beginning. We have to wait for the grass to wake up and start growing in. That’s frustrating for a lot of golfers, to have us aerate the greens just as they get nice, but trust me, they are going to heal way faster than if we aerated earlier.

You mention an interesting term: growth potential. What’s that all about?

Growth potential is how quickly the grass is able to grow given the temperature. In the middle of the summer, our growth potential in coastal Rhode Island is nearly 100 percent, but in the winter months, that number is far lower. For example, in December through February, our growth potential at Shelter Harbor is zero. The grass is completely dormant.

Should you repair pitch marks on cored greens? We asked a superintendent

What growth potential are you looking for to be able to aerate greens?

We like to have the growth potential reach 50 percent. That’s when we feel comfortable that the grass will recover after aeration. Where we are in Rhode Island, it takes a few months to reach that threshold – usually about mid-May. In April, the growth potential is only about 10 percent, so if we were to aerate then, then the grass wouldn’t grow back in very well.

Of course, it’s worth mentioning that growth potential varies across grass types and location. For courses south of us, they might hit that 50 percent growth potential in April. It’s all about knowing your climate and adjusting your schedules accordingly.


When do you core again after that?

We aerate again on the day after Labour Day (early September in the US). Just like in the spring, it’s essential to time it right. If you aerate too late in the [autumn], when the grass has stopped growing and the growth potential is low, then the greens won’t recover before the winter. That’s a disaster. On the coast in Rhode Island, our growth potential nosedives in October, so it’s key for us to aerify and have the greens grow back in before October hits.

For any golfers frustrated about aeration, I get it, but if we don’t do it, the greens will really suffer. For us to get the greens in the best shape for the longest time, we need to do it a few times a year.

Ask A Super: We all want fast greens, why can’t you just cut them shorter?