How to Apply Dawn to Kill Moss

Moss is an opportunistic plant that can quickly move in and spread throughout areas of the garden where other plants or grasses fail to thrive. Moss likes moist conditions, shade and acidic soil. The plants reproduce by spores rather than seed. Eradicating moss already in the garden with Dawn brand liquid dish detergent does work. However, a Penn State Center for Turfgrass Science study concluded that it is not as effective as other methods.

Dawn or Dawn Ultra liquid dish soap

Water

Mister bottle or garden sprayer

Rake

Mix 10 ounces of Dawn dish detergent with 2.5 gallons of water. For smaller applications, mix 2 tablespoons of detergent with 1 gallon of water.

Pour the mixture into the spray bottle or garden sprayer tank. Set the bottle sprayer to the "mist" setting. Pump the handle on the garden sprayer until the unit is pressurized. Check the garden sprayer setting by briefly spraying some of the mixture on a safe surface, such as the driveway. The spray should function smoothly with no leaks. Adjust the nozzle to produce a broad cone of the detergent mixture.

Use the spray bottle to mist smaller patches of moss or treat larger patches with the garden sprayer. Drench the moss thoroughly but be careful not to spray adjoining plants or grass.

Reapply the detergent mixture daily, if needed, until the moss turns brown and dies.

Use the rake to scrape and gather the dead moss. Dispose of the dead material away from the garden to eliminate any viable spores that may remain.

Monitor the area and re-treat if new plants sprout.

Spray in late spring or late summer to thwart the moss before its produces spores. The spray is most effective on warm, sunny days, and Dawn Ultra appears to work faster than regular Dawn.

Use leftover spray to target broad-leaf weeds as they emerge, being careful to spray only the weed.

Do not spray moss on windy days, as the mixture may be blown onto desirable plants and kill them.