When to apply grub control
in Delaware
Enter your Delaware ZIP code. We'll tell you the best time to apply grub control — based on real weather station data and Growing Degree Days.
Data details
Recommended Products
Chlorantraniliprole
Scotts GrubEx
Must be applied before grubs are active; needs watering in
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.
Grub Control GDD Thresholds
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.
About Delaware Lawns
Delaware is in USDA Hardiness Zones 7a-7b. Common grass types include Tall Fescue, Kentucky Bluegrass, Perennial Ryegrass.
For more lawn care information specific to Delaware, visit the University of Delaware Cooperative Extension.