Snapshot 2.5 TG Herbicide is not labeled to prevent mugwort and will not kill anything actively growing nor is it for use in lawns. According to an article from the NC extension office there are no pre-emergents for it.
Depending on the type of grass you have Quincept is labeled to control it as a post emergent application.
While Snapshot 2.5 TG Herbicide - 50 lbs. is a great pre-emergent for ornamentals, you may consider Ferti-lome Over the Top II Grass Killer or Gordons Ornamec 170 Grass Herbicide as a post-emergent. Both products are safe for ornamentals.
While Snapshot 2.5 TG Herbicide - 50 lbs. would prevent listed weeds, it would not prevent grasses. Eraser Max Super Concentrate Herbicide would be a better choice as it would prevent both grasses & weeds for up to a year. You just need to make sure you use enough water so that the product goes past the gravel & makes contact with the soil
Our warehouse that ships Snapshot 2.5 TG Herbicide - 50 lbs. is located in Lawrenceville, GA