I just moved Redding, California and I want to know if I can grow citrus trees?
A There are several microclimates in the Redding area where citrus do very well with little need for frost protection. But the seasonal temperature highs and lows in your area may dictate if the citrus survives or thrives. The optimum temperature range for citrus growth falls between 70°F and 90°F. Most citrus growth stalls when lower than 55°F, or when above 100°F, and some varieties also won’t ripen their fruit when temperatures rise above 100°F. Generally speaking, citron, lemons, and limes are particularly susceptible to frost damage. Grapefruit, mandarins, and oranges have a medium sensitivity to frost damage. Kumquats and Satsuma mandarins can be quite frost hardy.
Citrus can be grown outside in USDA Hardiness Zones 8-9 with frost protection such as insulating the trunks with fiberglass, cardboard, or an old blanket stacked up to the main branches. Wrapping the insulation layer with plastic will also aid in keeping it dry during rain, but plastic alone will not protect the trees from frost. Microclimates can be created in the yard by placing trees in a protected area, such as close to the wall of the house, to prevent frost damage. Few citrus appreciate high winds, but good air circulation can help prevent frost damage, minimize pests, and diseases.