How to Kill Nutsedge
How to kill nutsedge with sedge-specific herbicides. Product options, application timing, and why standard weed killers don't work.
Roll the stem between your fingers. If it has three edges (triangular), it's a sedge and requires sedge-specific treatment. If the stem is round or flat, it's a grass-type weed and needs a different product. Using the wrong herbicide class is the most common nutsedge treatment mistake.
Halosulfuron (sold as Sedgehammer) is the most widely available and effective option for homeowners. Sulfentrazone (in products like Dismiss) works faster but can temporarily discolor some turf. Both are selective and safe for most lawn grasses at label rates.
Treat when nutsedge is actively growing in summer (June through August) and plants have 3 to 8 leaves. The herbicide needs to absorb through leaves and translocate to the tubers. Stressed or drought-dormant nutsedge won't absorb effectively. Water the lawn a day before treating if dry.
Leave treated nutsedge unmowed for at least 48 hours before and after application. The herbicide needs maximum leaf surface for absorption. Mowing before reduces leaf area. Mowing after removes the herbicide before it translocates.
One application kills visible plants but dormant tubers produce new shoots. A second application 6 to 8 weeks later catches the next flush. Severe infestations may need treatment across two full growing seasons to exhaust the tuber bank.
