Growing Degree Days / Hours

Plant development depends on the accumulation of heat. Accumulated Growing Degree Days/Hours (GDDs) can be used to predict when a crop will reach a particular growth stage. Two calculation methods are presented by McMaster and Wilhelm (1997); ZENTRA Cloud uses Method 2 for GDD/GDH.

How Method 2 works

Method 2 applies a value check against the maximum (Tx) and minimum (Tn) temperatures before calculating the average temperature (Tavg):

Tavg = (Tx* + Tn*) / 2

Where Tx* and Tn* are the adjusted maximum and minimum temperatures:

• If Tx is greater than the upper temperature limit, Tx* is set to the upper limit.
• If Tx is less than the base temperature, Tx* is set to the base temperature.
• If Tn is greater than the upper temperature limit, Tn* is set to the upper limit.
• If Tn is less than the base temperature, Tn* is set to the base temperature.

Supported sensors

Growing Degree Days/Hours can be calculated from any temperature measurement.

Recommended sensors

• ATMOS 41
• ATMOS 41W
• ATMOS 14
• VP-4
• VP-3
• ECT

Create a Growing Degree Days model

1. On the Data page, select New Data.
2. Select Growing Degree Days as the type.
3. Select one or more temperature data sources.
4. Edit the data stream color.
5. Edit the data stream name.
6. Click the temperature to set the Base temperature and Maximum temperature. The maximum temperature is optional.
7. Select Create to finish.

The new data stream(s) will now appear in your data list.

How-To-Video