when to fertilize grapefruit
Soil pH and Fertilizer. Keep the soil pH more acidic, around 6.0 to 6.5. You can test the soil pH every few growing seasons and add dolomite limestone to raise the pH if necessary. You can add sulfur to lower the pH. When growing grapefruit in Florida, fertilize the trees three times a year with a citrus fertilizer; in California, only add nitrogen. Your best bet is to have the soil around the root base tested to make sure your grapefruit tree has all the nutrients it needs.