Steve from Bainbridge writes
You can apply Snapshot to established ornamentals as listed on the product label as long as the ground is not frozen and there is not snow on the ground. You want to apply pre-emergents before your target weed seeds germinate. Crabgrass seeds germinate when the soil temperature is around 55 degrees, but this threshold is higher for other weeds. You can also choose to do split applications in Spring as long as you do not reapply at the higher rate before 60 days, and you do not exceed the annual maximum rate of 600 lb per Acre, per the product label.
Answer last updated on: 02/01/2018