GROWING CITRUS TREES IN REDDING, CA.

July 8, 2017 ptillman

QUESTION:  

 

I just moved Redding, California and I want to know if I can grow citrus trees?

 

ANSWER:  

 

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.

 

Mulches are valuable during the warm months for conserving soil moisture and keeping the roots cool, but during the cold months mulches actually prevent the radiant heat of the soil from protecting the citrus tree trunks. Scraping the mulch back from within the drip line and keeping the soil evenly moist during frost warnings will help protect the trunk and the roots from frost damage. Additional frost protection can be obtained by placing a 100 watt light in the interior of the tree, as will using a string of old fashioned holiday lights wrapped around the tree. [Note: LED lights give off no heat and will not prevent frost damage].  Citrus need to be fertilized to produce fruit but timing fertilizer applications is also important especially if you are living in an area prone to winter frosts. Fertilizing stimulates tender new growth in citrus, but if it is done too late in the summer an early frost can damage the tender leaves. Citrus fertilization is best done no later than August to allow foliage time to harden off before frosts. Citrus are quite varied in their bottom line temperature tolerances before they succumb, but even those who live in the cold Zone 7 can grow citrus in pots that  can moved indoors, to an enclosed atrium or patio, or perhaps in a well-lit garage to spend the winter.

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