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.
Built on NOAA GHCN-Daily observations covering 33,000+ US ZIP codes, recomputed daily.
Data details
What to buy for this result
Some links are sponsored. We may earn a commission, but your ZIP result determines which product type we show.
Preventive grub control
Chlorantraniliprole
Scotts GrubEx
Best fit: Only if prevention is warranted, such as a relevant prior grub infestation. Follow the exact product label and local Extension timing; GDD is a timing signal, not proof of grubs.
Helps you avoid paying for rescue treatment later when timing still favors prevention.
Must be applied before grubs are active; needs watering in
Separate rescue option — confirmed damage only
Carbaryl
Sevin Lawn Insect Granules
Best fit: Only for confirmed active grub damage: lift turf and confirm live grubs and active feeding before buying. Follow the exact product label and local Extension guidance; GDD does not prove infestation or that rescue will still work later in the year.
Rescue effectiveness depends on grub stage and active feeding; do not treat merely because the GDD window has passed.
At the label's 9 lb per 1,000 sq ft white-grub rate, a 10 lb bag treats about 1,100 sq ft — well under the bag's 4,292 sq ft headline coverage
How GDD Predicts Grub Activity
Growing Degree Days (GDD) track accumulated warmth from air-temperature observations since January 1. This tracker uses 1,000–1,300 GDD as a broad preventive timing window. It does not observe beetles, eggs or grubs in your lawn. Product-specific timing and local Extension guidance take precedence.
- 0–800 GDD Too early. Soil is still warming up.
- 800–1,000 GDD Getting close. Optional preparation if prevention is warranted; do not apply yet.
- 1,000–1,300 GDD Preventive timing window, if warranted; check label and local timing.
- 1,300+ GDD Window closing. Rescue only for confirmed active grub damage; check label and local guidance.
Source: University of Wisconsin–Madison Division of Extension — adult Japanese beetles emerge around 1,000 growing degree days, with egg-laying and hatching soon after.
Why Grub Control Timing Matters
Preventive products such as chlorantraniliprole need time to reach the root zone before young grubs cause damage. Prevention may be warranted after a relevant prior infestation; many lawns need no pesticide. Rescue is a separate decision for confirmed active grub damage. Larger grubs can be harder to control, and treatment may be ineffective once feeding stops. Check the exact label and local guidance.
This tracker pulls daily temperature observations from your nearest NOAA weather station and calculates GDD and estimated soil temperature for over 33,000 US ZIP codes.
Common grub control questions
When should I apply grub control?
Apply preventive grub control before newly hatched grubs begin feeding on roots. This tracker treats roughly 1,000–1,300 GDD (base 50°F from January 1) as the apply-now window — enter your ZIP code for your local status.
When should I apply GrubEx?
If prevention is warranted, follow the GrubEx label and local Extension timing. Chlorantraniliprole needs time to move into the root zone; the label calls for spring or early summer application. This broad GDD estimate does not override product-specific timing. Water in as directed.
When do grub eggs hatch?
Japanese beetles, masked chafers, and other scarab beetles lay eggs in early to midsummer, and eggs can hatch roughly two weeks after laying when soil moisture is favorable. Local heat accumulation shifts the exact timing from year to year.
Is it too late for preventive grub control if my lawn is already damaged?
Brown or damaged grass alone does not establish a grub infestation. Lift turf near the damage edge and confirm live grubs and active feeding. Only then consider a curative product under its label and local Extension guidance; a preventive product is not rescue for existing damage.
How many grubs per square foot justify treatment?
Healthy turf tolerates a few grubs per square foot. About 10 or more grubs per square foot, roots eaten back, or turf that lifts like loose carpet are stronger reasons to treat and to plan preventive control for the next season.
Guides by State
Timing varies across the country. Find your state for local timing windows.