Johnsons 4.25kg Tuff Grass Lawn Grass SeedTuffgrass with dog patch resistance New improved Tuffgrass is a unique product with proven ability to create dog patch resistant lawns and be tough enough to stand up to the wear and tear of family use. The development of dog patch resistant grass seed is based on rock solid data from trials, with the product rigorously tested by scientists at DLF Seeds in Denmark, the parent company of Johnsons Lawn Seed. Scientists conducted 672 tests to simulate