UP TO 6 MONTHS
Preemergent weed control is a water-based application that is sprayed over dirt, landscaped rock, or lawn areas in order to get a handle on the growth of broadleaf annual weeds. Meaning, "before emerging," the preemergent material stops seeds from germinating and prevents weeds from developing before they start.
Since this type of material only affects seeds, it can be sprayed over existing plants without having an effect on them. The preemergent material's effects last between 6 and 8 months, and no matter the surface, regular applications are important to keeping your property weed free.
Post-emergent liquids, on the other hand, are applied directly to unwanted weeds to kill them. The systemic material, absorbed through the leaf or skin of the plant itself, is pulled into the root and ensures the death of the weed. This type of application is effective on dirt, rock landscaping, and lawns.
Selective post-emergents can be used on lawns to kill broadleaf weeds, but leave wanted grasses unharmed. Care should be taken when using these materials around ornamental plants, especially on rainy days.