You can probably recall a round of golf where you putted well, maybe even made a few long putts and commented that you “liked the greens.” This is probably due to the fact that the green speed – which is the condition of putting as it relates to ball-roll distance – suited your putting stroke.
The speed of a putting green is measured by using a Stimpmeter – a tool used invented by the USGA and used by golf course superintendents to make a standard measurement of the relative speed and uniformity of the putting greens. If a green has a long ball roll when measured with the Stimpmeter, it is considered fast and if the green has a short ball roll, it is considered slow. Its purpose is to keep the greens as consistent as possible throughout the golf course.
While a golf course superintendent tries to maintain that consistency in the green speed, it’s important to know that green speed changes all the time. Even if you play the same course multiple times a week or during the month the green speed is likely to change. Green speed not only changes from month-to-month, or day-to-day, but even within the day from hour-to-hour due to the weather environment and how the grounds staff maintains the green.
Weather and environmental conditions like temperature, humidity, the sun, moisture, type of soil, time of day, etc. all affect the speed of the green and how the ball will roll. If you play early in the morning when dew is present on the greens, they will roll slow. As the temperatures increase during the day and the greens dry out, the speed of the green increases. How the greens are maintained will affect the ball roll as well, depending on the type of mowing height, rain or irrigation on the greens, if the greens are rolled and how much fertilizer, topdressing and aerating is done to the greens.
Knowing that the green speeds vary from day-to-day will help you on the course. Take time to visit the practice green before you play to get a feel for the green speed. Hit some long putts and watch how they roll. If your ball traveled well past your target, you may need to adjust for fast greens. The opposite is true if you hit a putt that doesn’t get to the target – you may be playing on slow greens. Take this knowledge to the course and be prepared to adjust your putting stroke if the green speeds change during your round.