St. Augustine soil temperature guide

NC State Extension recommends applying nitrogen in May or two weeks after green-up, whichever is latest, and notes that preemergence herbicides may be used in mid-to-late February where crabgrass and goosegrass have been a problem. That regional calendar should be adjusted to your lawn, weather, soil, and product label.

St. Augustinegrass is sensitive to certain herbicides, so label fit matters. NC State's St. Augustinegrass calendar gives specific soil-temperature triggers for large patch prevention: apply a preventive fungicide in fall when soil temperatures drop to 80°F, continuing monthly until temperatures drop below 60°F; apply in spring when soil temperatures reach 55°F for four consecutive days. Combine those signals with visible turf condition and the product label before acting.

• Check local soil temperature before pre-emergent and disease-timing decisions.
• Use the app to log which active ingredient was applied, rate, water-in notes, and turf response.
• Keep photo history so future spring decisions are based on your lawn, not just regional dates.