How much sunlight is enough?

       Its common knowledge that grass needs sunlight to grow. Sunlight is absorbed by the turf and used to release oxygen and reduce carbon dioxide into energy. This energy is used for various vital plant functions. But how much sunlight does a plant need? Ten hours? Twelve? More sun in the morning? Or the afternoon? We set out to answer these questions and provide solutions with regards to our MiniVerde greens at the Players Club.
       We downloaded a sun path application to our smartphones to chart the amount of sunlight our green's are receiving. This application can be found here. The goal was to quantify the sunlight amounts. We wanted to gain some perspective into the sunlight debate. What we found was that turf needs adequate sunlight all season. Even when the turf is dormant, seven hours of sunlight is necessary for optimal surface conditions.
     We collected our information from 27 points over the nineteen putting green's. We took readings from the center of every green, then added eight other points of reference. The supplemental sections are our trouble spots from this past season. We wanted to cross-reference good vs bad in hopes of drawing conclusions as to why certain green's struggle more than others. What we found was that 95% of our problem areas are directly related to average sunshine.
          Below is an excel spreadsheet of the data that we observed. It is not the raw data; but averages calculated from the sun's patterns throughout the season. There are five columns. The first is an average for the entire year. The second through fifth columns are averages from the four trimesters of the year, January-March, April through June, July through September and October through December, respectively. The spreadsheet is interactive, so you can scroll through to see all of our statistics.




        When we first calculated the averages we took a "which one isn't like the others" approach. This helped us to arrive with a target value for each column to compare. The first column (12 month average) we concluded that a value greater than nine hours was our benchmark. We repeated this step until we found a target value for each column. These values are highlighted in blue.
        Our next step was to highlight every value that fell below our benchmarks in each column. We highlighted these values in yellow. Once we had the color contrast to visualize we came to the immediate conclusion that our average sunlight needs to increase. But what was more interesting were the highlighted cells versus the non-highlighted cells.
        The first five greens at the Players Club were by far our best performing greens. Now you can look at the chart and see these five greens have only one highlighted cell. Is this a coincidence? No, absolutely not. These greens meet all our minimum requirements of average sunlight throughout the day for the entire year. This discovery only strengthened our beliefs that reduced sunlight directly impacted green's performance.
        As you continue down the chart you can see the correlation between turf quality and average sunlight. But which sunlight is most important? Some turf professionals will tell you, clear everything from the hours of 9 AM to 3 PM on December 21st and your troubles will be gone. However, our study has found that its not as "clear cut" as that. Let's use the back of #9 green for example. It has full sun on December 21st from 9:00 AM until 4:30 PM. That is seven and a half hours of sunlight on the shortest day of the year. Yet the 12-month average is still 30 minutes below our acceptable limit. As we look at our chart we see that this green averages 20 minutes below our limits from January through March. The average daily sunrise for this green is 9:30 AM during these months. So, from this we concluded that the simple, somewhat vague answer to the "What sunlight is the most important?" question is: All of it. We feel that maintaining an average, consistent with our "target values", over the entire year is the goal.
        Our next step is to implement a plan to increase our annual sunlight averages. We begin by singling out the undesirable figures from column one.  We then scroll horizontally to find out when sunlight is most restricted. These figures are highlighted in red. We take these figures to the field and pinpoint the limiting factors. Let's look at the front left of #14 as an example.
        The data provided shows us that the front of #14 receives 8 hours and 33 minutes of sunlight, on average, throughout the year. This is below our nine hour threshold. We then scroll right and find the lowest average trimester; that is January through March. During these months, the green's surface averages 7 hours and 40 minutes of sunlight per day. This is below our desired level of 8 hours at this time of year. This amount is the limiting factor regarding our annual average. We must now travel to the site and plan our removal strategy.
        Once on site, we use our Sun Surveyor application to target the specific trees for removal. We program the app to show the sun's path during our limiting months. The path is then traced over the actual landscape on the smartphone's screen. We can now pinpoint the exact tree(s) that need to be removed and reduce removing unnecessary plant life.
       We plan to use this process to scout tree removal over the remainder of the winter. We will be diligently working to remove limiting factors to ensure premium putting surfaces next season. The use of smartphone technology and our collected data allows us to remove trees with maximum efficiency. This allows us to complete our work in a timely manner and reduce disruption to the golf schedule. Over the next few months we will be continuing to improve our sunlight averages. You can use the spreadsheet above to follow along and determine exactly why and what we are removing.