Hawaii · 4 cities
When to apply crabgrass preventer in Hawaii
Soil below 50°F last winterRarelyThe soil here stayed above 50°F through last winter, so the 50 to 55°F soil-temperature rule gives no spring window. Time pre-emergent to your local calendar.
Today
Season over
4 of 4 cities
Window last spring
–
median gap from 50°F to 55°F
Soil today
76°F
median, 0–4 in
Never below 50°F
4
cities with no spring window
Every Hawaii city
Spring 2026 dates and today's verdict.
| City | Held 50°F (2026) | Held 55°F (2026) | Soil today | Today |
|---|---|---|---|---|
| Honolulu, HI | never below | never below | 76°F | Season over |
| Hilo, HI | never below | never below | 66°F | Season over |
| Kahului, HI | never below | never below | 80°F | Season over |
| Wahiawā, HI | never below | never below | 76°F | Season over |
Crabgrass seeds start to germinate once the top 2 to 4 inches of soil stay near 55°F for several days. A pre-emergent works as a barrier in the soil, so it has to be down and watered in before that: the usual advice is to apply it while the soil holds 50 to 55°F. The dates here are when the modelled soil began to hold each temperature last spring; this year's window will move with the weather, which is why each city page shows today's reading and the 7-day forecast.
Questions
- When should I put down crabgrass preventer in Hawaii?
- The soil here rarely drops below 50°F, so follow the product label and local timing rather than the soil rule.
- Is it too late to apply pre-emergent?
- Once the soil has held 55°F for a week or more, crabgrass is germinating and a pre-emergent will not stop the seedlings already up. Each city page says which side of that line it is on today.
Soil temperature today in Hawaii →
Data: Global Forecast System (GFS) 0.25°, soil temperature 0–10 cm (TSOIL) (NOAA National Centers for Environmental Prediction (NCEP)); GeoNames gazetteer (cities15000) (GeoNames).