Source: Plant Hardiness Zones | USDA
The USDA Plant Hardiness Zones are the standard by which gardeners and growers can determine which plants are most likely to thrive at a location. The map is based on the average annual minimum winter temperature, divided into different zones. Citrus is typically found in Plant Hardiness Zones 8, 9, and 10. The color of the fruit only develops in the climates with a cool, or temperate, winter. In tropical regions, with no winter, the citrus fruit remains green until maturity. The citrus trees do well when planted in sandy or loamy soil with slightly acidic to neutral soil pH.