There is not doubt art and science are involved in Greenkeeping. As Superintendents, we try to quantify as much as we can because its easier to rely on the science portion of the job.
As a way of quantifying data to aid in the decision making process, we started using the GDD (Growing Degree Day) model. It sounds more complicated than it is. To calculate growing degree days, I take the high temp + low temp for the day /2 and subtract the base temp. The base temp is 50* because we know when temperatures dip under 50 degrees, grass isn't actively growing. Again:
(high daily temp- low daily temp)/2 - base temp= GDD
For example: Todays High is 72 and low is 51.
72+51 /2 - 50 = 11.5 growing degree days
Another example: Today high is 58 and low is 42
58+42 /2 - 50= 0 growing degree days
This means no growth occurred on this day. If the answer is a negative number, it remains 0.
Above, you can see examples of how many cumulative GDD are required for a specific events to occur that affect the turf. If I want to spray a growth regulator to prevent Poa annua seedhead from forming, I need to spray the turf after 220 growing degree days are met.
This is just an example of technology and science and how we use it to our advantage.