Growing Degree Days

This information is updated weekly from March through October to provide current data for use in making pest management decisions.  

The accumulated Growing Degree Days value from October 6, 2020 to October 12, 2020 is:

4259

About Growing Degree Days (GDD)

The GDD are a measure of heat accumulation used by horticulturists, gardeners, and farmers to predict plant and animal development rates.  For example:

  • Determine stage of crop development and maturity
  • Predict insect emergence from dormancy and developmental life stage
  • Estimate plant development and reproduction

By monitoring the GDD on a daily or weekly basis it is possible to make accurate and timely decisions to protect and enhance your crop or plants.

Growing Degree Day values for various insects

Pest Minimum GDD
Eastern Tent Caterpillar 92
Pine Tip Moth 121
Pine Spittlebug 148
Azalea Lace Bug 239
Two-spotted Spider Mite 363
Euonymus Scale 406
Boxwood Leaf Miner 448
Bagworm 600
Fall Webworm
867
Japanese Beetle
970

How It’s Calculated

Calculating GDD is determined by the difference between the daily average air temperature and the base temperature of 50 degrees Fahrenheit (10 degrees Celsius). 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:

  • Max Temperature plus Minimum Temperature divided by 2 minus Base Temperature equals the Daily GDD