Diesel is a toxic compound that kills grass as well as ornamental plants, worms, weeds, and insects. You'll struggle to clean up the mess if diesel spills, splashes, or sprays on your grass. The plants harmed by the diesel spill won't recover since it will take a long time for the diesel to break down. There is a good chance that nothing will grow there as long as the diesel does not degrade. In less than an hour, diesel will destroy the grass, and the entire plant will rot within 48 hours. A tiny spill can kill plants in a large area. Most plants will die rapidly.