1. The document outlines the seven tenets of sustainable gardening: obey your sense of place, nourish the soil, strike a balance, manage water wisely, encourage diversity, practice prevention, and share the utility you create. 2. It emphasizes working with nature rather than against it, such as nourishing the soil by encouraging worms and microorganisms, managing water through techniques like rain harvesting and contouring, and maintaining diversity through multi-function stacking. 3. Sustainable gardens are described as edible, low maintenance, functional, and happy places that create beauty and peace for others while having lower costs and environmental impacts through practices like prevention and conservation of resources.