Using a weed torch is only effective on annual weeds. Anything perennial will just come back, and fairly quickly at that. We just went through that trying to clean up my dear departed doggie's kennel. We torched everything. Then when it cooled off, we sprayed it with Roundup. Still got thistles and perennial grasses coming up. So we sprayed it again. Most of it is dead now, but there are still a few isolated spots that will require work. But the torch definitely gets rid of a lot of the upper growth (we had weeds that were 3 to 4 ft tall!).
