“It was 80 degrees the other day, why aren’t we green yet?”
The short answer: it’s all about the temperature. The effects of cold winter temperatures, along with ongoing colder night temperatures, are delaying our spring green-up. Although we’ve had warmer afternoons recently, our nighttime temperatures have fluctuated in the 40’s for the past week. We continue to evaluate golf course conditions and address areas that are concerning or are unobtainable. Diving deeper, below I’ll explain how actual data is used to compare Potential Growth vs. Temperature.
What about Temperatures? The optimum average growing temperature for cool season grasses is 67.5 degrees. For warm season grasses, it’s much higher at 87.5 degrees. Growth Potential (GP) is a way to put a numerical value on the ability of the turf to grow. GP was developed by Pace Turf to describe the relationship between turfgrass growth and temperature.
We can look at last week’s data to compare the temperature to the potential for turf growth. The average temperature last week was 58.8 degrees. For our warm season grasses – fairways, tees and bermuda rough – that was 28.7 degrees below the optimum growing temperature of 87.5 degrees. For our cool season grasses – fescue rough and bent grass greens – that was only 8.7 degrees away from optimum growing temps.
The Growth Potential (%) for the week of April 3-9 was calculated at 5.8% for warm season turf and 65.5% for cool season turf. Data for the individual days is shown below:
| Day | Date | Avg. Temp. | GP% Warm | GP% Cool |
| Mon. | 4/3 | 58.1 | 4.5% | 61.3% |
| Tue. | 4/4 | 72.1 | 41.6% | 91.9% |
| Wed. | 4/5 | 72.5 | 43.4% | 90.4% |
| Thu. | 4/6 | 55.6 | 2.6% | 46.4% |
| Fri. | 4/7 | 46.8 | 0.3% | 50.7% |
| Sat. | 4/8 | 50.7 | 0.8% | 22.4% |
| Sun. | 4/9 | 55.4 | 2.5% | 45.2% |
With almost perfect conditions leading up to Thursday for cool season grass (fescue rough), and with rain events on 4/6 of 2.5”, you might have thought that you were playing U.S. Open roughs throughout the weekend. On the flip side, we never crossed 44% Growth Potential for warm season grass, our tees and fairways. Hopefully this data will help provide a better understanding of the reasons behind the delay of spring green-up on our Bermuda grass.
Posted below is further reference data on Growth Potentials provided by Paceturf.org. If you have any questions feel free to email me at Tyler.Ingram@invitedclubs.com.
