GDD Tracker

When should you
apply grub control?

Enter your ZIP code. We’ll tell you the best time to apply preventive grub control — based on real weather station data and Growing Degree Days.

How GDD Predicts Grub Activity

Growing Degree Days (GDD) track accumulated warmth in your soil since January 1. When the average daily temperature exceeds 50°F, the difference is added to your running total. Japanese beetles and other scarab beetles emerge to lay eggs when GDD reaches roughly 1,000–1,300. Preventive grub control products need to be in the soil before those eggs hatch — that’s the window this tracker identifies.

0–800 GDD Too early. Soil is still warming up.
800–1,000 GDD Getting close. Plan your grub control application.
1,000–1,300 GDD Apply now. Ideal window for preventive grub control.
1,300+ GDD Window closing. Consider curative treatment instead.

Why Grub Control Timing Matters

Preventive grub products like chlorantraniliprole (GrubEx) work by creating a treated zone in the soil that kills grubs as they hatch and begin feeding on roots. Apply too early and the product may degrade before peak egg-laying. Apply too late and grubs are already established — you’ll need a more expensive curative product. GDD tracking ties your application to actual soil temperature rather than calendar dates, which vary from year to year.

This tracker pulls daily temperature observations from your nearest NOAA weather station and calculates GDD for over 33,000 US ZIP codes.

Guides by State

Timing varies across the country. Find your state for local timing windows.

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View all 50 state guides