Corn Weed Blocker is a pre-emergent weed suppressant that inhibits weed seeds from germinating in established lawns, vegetable gardens and flower beds while also acting as a slow release fertilizer due to its 9% Nitrogen content. Corn Weed Blocker is safe to use around new plants with existing root systems like transplants and grass sod, and unlike chemical herbicides, is also harmless to people, pets and ground water.