Growing Degree Days (GDD) and Rainfall Through September 4th

Jarrod O. Miller, Extension Agronomist,

There is some shelling going on in Sussex County this week, with word that many fields will start on Monday. Any field planted between April 22 and May 20 should be in blacklayer, and the high temperatures this week should really help in reducing moisture content. If you planted over a range of dates, you should be able to roll through your fields week to week, depending on your variety. Most fields planted in early to Mid-June should be in R5 (dent), which you can check by watching the milk line (

R5 (Dent): 2190-2450
R6 (Blacklayer): 2700

Table 1: Accumulated growing degree days based on planting dates through September 4th.

If you planted
Sussex Kent New Castle
22-Apr 3179 3109 3000
29-Apr 3126 3062 2966
6-May 3018 2952 2868
13-May 2914 2846 2771
20-May 2803 2740 2676
27-May 2645 2580 2528
3-Jun 2492 2429 2378
10-Jun 2370 2312 2265
17-Jun 2234 2185 2136

To match most of the season, rainfall around the state over the last week was scattered with variable intensity. From the graph below, it appears that Dover took a pretty hard hit (2.47” on Aug 31st), but most of the state received about an average of 0.5” over the weekend. On DEOS I did observe at 5.39 inch rainfall in Oakley and 4.20 inches at the Prime Hook Wildlife Refuge.