Plants in the garden (and insects too) develop based on something called "Growing Degree Days" or GDD for short. This is an accumulation of heat units using a base of 50 degrees. For every degree above fifty goes towards the growing degree-days and plant development. Most of us do not follow GDD, but really on the catalog or seed packet information on how long it takes to go from seed to harvest. You will see a variety listed as a short or long season plant. Those that have grown sweet corn are very familiar with these terms. The same can be said for tomatoes.

It has been an interesting spring and early summer watching the recorded numbers and comparing them to the historical averages. The sample below is indicating that the St. Charles reporting station has shown us slightly ahead of the historical average. I can only guess that given our cooler weather the predicted GDD for the next two weeks will be changing downward.

Modified Growing Degree Days (Base 50°F,March 1 through July 10)

Station Location	Actual Total	Historical Average (11 year)	One- Week Projection	Two-Week Projection
Freeport	1499	1249	1659	1820
St. Charles	1299	1183	1451	1605
DeKalb	1296	1313	1451	1608
Monmouth	1448	1382	1610	1776
Peoria	1511	1459	1685	1862
Champaign	1604	1506	1782	1964
Springfield	1762	1617	1950	2139

You would expect t that as you move from north to south in the state, GDD would be accumulating at higher levels than northern Illinois. This matches up well with the typical planting dates throughout the state that gardeners use to begin their vegetable growing season.

If our weather pattern continues on the cooler side, those warm loving vegetables will be delayed in their development, which will delay any fruit set. The opposite has been seen on those vegetables and flowers that enjoy cooler temperatures; they are still growing very well.

This continues to be a "wait and see what happens" kind of summer.