I have thistle in my flower gardens that WONT DIE!! Is there something specific I should be using rather than my general weed killer??
You may need to resort to spot treatment with a non-selective herbicide such as roundup. Use caution when spraying so that you avoid getting any roundup on other plants, because it can kill other vegetative plants it comes into contact with. You could also use a paint brush to paint some of the roundup onto the thistles to prevent any spray droplets from reaching other plants.