Growing Degree Days

Growing Degree Days (GDD) are used to estimate the growth and development of plants and insects during the growing season. The basic concept is that development will only occur if the temperature exceeds some minimum development threshold, or base temperature (TBASE). The base temperatures are determined experimentally and are different for each organism. The Platform uses a base temperature of 10°C (50ºF) for GDD calculations.

To calculate GDDs, you must first find the mean temperature for the day. The mean temperature is found by adding together the high and low temperature for the day and dividing by two. If the mean temperature is at or below TBASE, then the Growing Degree Day value is zero. If the mean temperature is above TBASE, then the Growing Degree Day amount equals the mean temperature minus TBASE. For example, if the mean temperature was 17°C, then the GDD amount equals 7 for a TBASE of 10°C. 

GDD = TMEAN − TBASE, if TMEAN is greater than TBASE GDD = 0, if TMEAN is less than TBASE where TBASE = Growing Degree Days base temperature TMEAN = mean temperature, (TMAX + TMIN)  ⁄  2

GDD = (TMAX + TMIN)  ⁄  2 − TBASE

In the Platform GDD calculated from data provided by weather stations closest to a particular field — both private and global.

The user can find GDD on a personalized page of any field. Just choose the required one on any fields map or in any general fields list. Make sure you have selected the right field group and season in the Navigator (located in the right corner of the Main Menu).

GDD is calculated for each field individually from the seeding date that the user provide on the field’s personalized page or in an agricultural operation (its end date) and from starting year⇒ the 1st January of each year for both the Northern Hemisphere and the Southern Hemisphere.

If the user don’t provide the information on sowing date, he won’t have data on GDD from starting sowing.