A question I am occasionally asked, is why green speed can change from day to day. It's a great question. Keep in mind, our target speed for our greens in an 11' stimpmeter reading. This is what we feel is a good number after factoring in the contours on our greens (see blog post on pin locations) combined with the overall skill level of our membership. When I say, 'we,' I refer to the support of the Green Committee over the years. Just because we shoot for 11 feet, doesn't mean one day you won't putt on 12' or 12.5'. On the flipside, you may see them as low at 10' on another day.
To answer this question, it is important to understand what impacts or creates speed and how does our maintenance practices or the weather affect that. Simply put, green speed is a factor of how much friction is working against the golf ball. The more friction, the slower the green speed. Less friction, means faster green speeds.
That said, here are a list of maintenance practices we do that work to speed up the greens and why:
1. Double cutting: This speeds up greens because we are removing more leave tissue that works against the golf ball.
2. Rolling: Smoothing the putting greens eliminates any imperfections on the surface (think about foot traffic) that can slow a ball down. Rolling a green results in anywhere from a 6" to 1' gain in the stimpmeter reading immediately after rolling.
3. Height of Cut: This one is simple. The taller the grass, the more friction.
4. Reduced Fertility: In the world of Superintendents, the word 'Lush' is not a compliment when describing turf. To me, it sounds like over-fertilized turf that is weakened and prone to fungus and insect damage. Think of a person who is physically fit vs. someone severely overweight. The overweight person likely has other heath problems that are attributed to their weight. Grass and plants are no different. The more food or fertilizer doesn't equate to good health. Reduced fertility means the grass has a finer texture, which leads to less friction on the golf ball.
5. Afternoon Greens Mowing: This is one of my favorites. The best quality of cut is one that's done to dry (no morning dew) putting greens in the afternoon. Mowing in the afternoon reduces leaf tissue and is a great way to pick up speed on the greens.
6. Aggressive Grooming: Grooming is the process of vertical mowing to thin out a stand of turf. As the putting green is thinned, there is less friction on the golf ball. The affects from this practice last about 2 days. After that, the grass has grown back to the initial density before the process. Therefore, if we verticut on a Monday, by Wednesday or Thursday, the greens may seem a little slower compared to the way they were earlier in the week.
7. Light and Frequent Topdressing: At Highlands CC, we apply a very light coating of sand over our greens every 10-14 days. Topdressing speeds up putting greens by smoothing the surface and also reducing the height of cut... from the ground up.
8. Water Management: Dry and firm greens are always much faster than wet greens. This is why we withhold as much water as we can from the putting greens. Grass that is drier, is not as succulent as damp turn. Succulent turf causes the leaf blade to swell and thus adds friction to the golf ball. This is why the greens at the US Open are brown. Water is withheld all week.
Now imagine as a Superintendent, having the ability to combine or schedule these practices to deliver the green speed that's appropriate for a golf event or for just daily play. It should also be noted that the practices listed above do come with some risk, some more so than others. You might have heard someone say "Speed Kills" when describing the practices above. While that could be the case, if you know what you're doing and understand the limits of your turf and the environment for which they live, one can achieve nice green speeds by employing the above tactics at varying degrees. Now that I mentioned the factors that we manage to keep the speed up, here are a list of factors that work against us, slowing the greens down.
1. Rainfall: This impacts not only the succulence of the turf, but also our ability to get out and work on the greens. When we get into days that are wet and have a lot of cloud cover, we will be much less aggressive on the greens because this is when damage can occur. Greens will always be slower when it is raining. We don't want to out pace the turf, doing more harm at a rate that's faster than the turf can heal itself.
2. Humidity: High humidity can also cause turf leaf tissue to swell, creating more friction.
3. Time of Day: All day, everyday, grass is growing. The greens will have more grass on them in the afternoon compared to the morning, right after they were mowed.
4. Time of Year: Depending on the time of year, green speed may not be our top priority. I am specifically referring to spring, when our focus is growing a dense stand of healthy turf that will make it through the summer. Later in the fall season, we also back off aggressive maintenance because the days are much shorter and the angle of the sun is so low, the greens aren't getting enough light to photosynthesize. Photosynthesis is the process that plants use to make food.
It is my hope that this gives you an idea of why the speed of the greens have some variation from day to day. As you can see, it is Mother Nature that has the greatest ability to affect the greens on a daily basis. Especially in Highlands, were we receive almost a 100" of rain, annually.