- Citrus fruits need well-drained loam or sandy loam soils, according to the University of California. In areas where the topsoil is thin or in desert areas with heavy clay soil under sandy layers, adding organic material such as compost or manure improves the soil texture and helps to hold nutrients and water.
- Usually the only fertilizer nutrient needed for grapefruit trees in California is nitrogen, according to Sunkist. Adding nitrogen fertilizer in late winter helps to support spring blooms. The University of California recommends feeding trees 1 to 1.5 lbs. of nitrogen fertilizer in late December to February. When irrigating grapefruit trees in California, it is important to provide water throughout the year and to avoid drought when trees are in bloom. Water quality is important. Water that is too high in salt can burn the trees, which is especially a problem in desert areas with alkaline soils, according to Purdue University.
- While frost rarely kills a healthy mature grapefruit tree in California, frost can damage or destroy the grapefruit growing on a tree. Frost risk comes when temperatures drop as low as 29 degrees Fahrenheit for 30 minutes or longer. Commercial growers in California generally use wind machines or water to protect grapefruit trees from frost.
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