Lawn Treatments for Weeds in March

Inspect the Lawn

• Early spring is a good time to inspect the lawn for actively growing weeds. Weeds form habitats, growing in the same areas each year. Crabgrass, which needs light to germinate, is found where grass has grown thin. Annual grassy weeds are strong competitors to grass plants and need to be controlled in early spring. High mowing stunts grassy weed growth, but a pre-emergent herbicide prevents them from getting a start at all.

Organic Pre-Emergent Weed Treatment

• Corn gluten meal pre-emergent herbicide can be spread on the lawn area. It requires water to start the chemical process that prevents weed growth. The weeds may germinate but are not able to establish a taproot to grow. It contains 10 percent nitrogen, which is a nutrient boost to turf grass plants. Corn gluten meal pre-emergent herbicide is non-toxic to people and the environment and does not pollute groundwater supplies.

Synthetic Weed Control Treatments

• Synthetic pre-emergent weed control treatments include Betasan, Surflan, Halts and Crab-ex. March 1 is the target date for applying these types of herbicides in temperate southern and western climates. Crabgrass seeds germinate when soil temperatures rise above 50 degrees Fahrenheit. Weed scientists recommend applying a pre-emergent herbicide when soil temperature at 1 inch deep reaches 52 degrees Fahrenheit. Synthetic herbicides have label warnings for safety precautions that must be followed. Synthetic chemicals may harm pets and children and cause environmental damage.

Preventative Weed Control

• High mowing prevents weed growth. The growing point for weeds is near the top of the plant. High mowing eliminates the weed flowers and seed heads. Frequent mowing prevents or reduces seed production in many weed species. Lawns that are irrigated deeply but infrequently have fewer weeds. Fertilizing the lawn in springtime feeds weeds as well as grass, so fertilize in the fall only. Mature compost used as fertilizer feeds the soil and provides a slow release of the 17 nutrients necessary to keep grass healthy and strong enough to compete with weeds.