What are growing degree days and how do we compute them?

Growing Degree Days (GDD)- are an attempt to quantify heat available for vine development during the growing season. By convention grape degree days are tallied between April 1 and October 31, and a base temperature of 50°F is used. Raw Data is provided The Pacific Northwest Cooperative Agricultural Weather Network (AgriMet).

GDD = Sum of (

Avg Daily Temp

) - 50) for all days April 1 to Oct 31

What is ETo and how is it computed?

Evapotranspiration (ET) is the loss of water to the atmosphere by the combined processes of evaporation (from soil and plant surfaces) and transpiration (from plant tissues). It is an indicator of how much water your crops need for healthy growth and productivity. ET from a standardized grass surface is commonly denoted as ETo. Daily ETo averages are provided by The Pacific Northwest Cooperative Agricultural Weather Network (AgriMet). For more information, please visit them at http://www.usbr.gov/pn/agrimet/index.html.