Sustainable methods to improve the garden without negatively impacting local flora and fauna include mulching, drip irrigation and biological pest control. After setting up a sustainable system, you can spend less time weeding and more time enjoying your garden and orchard. In the warmest areas of the United States, in United States Department of Agriculture plant hardiness zones 9b to 11, gardens include tropical fruits such as the Persea americana, the avocado tree. Native to southern Mexico, avocado trees thrive in Mediterranean climates when provided sufficient water and wind protection. Avocados respond well to sustainable gardening, as several techniques reflect their original growing conditions in Mexico and South America.