Time Frame-New Trees

• Fertilize new trees about three weeks after planting when the flower buds begin to swell, and then again every six weeks between February and October.
  
  

Time Frame-Established Trees

• Fertilize trees five years and older three times a year: early spring, early summer and late fall. Apply fertilizer at a rate of 1 pound for each year of age to a maximum of 10 pounds at each application.
  
  

Types

• Choose an 8-8-8 fertilizer on the NPK scale that contains micronutrients such as copper, boron, manganese and magnesium.
  
  

Considerations

• Apply fertilizer according to the tree's drip line. Spread fertilizer 1 foot for every year of age, up to 10 feet.
  
  

Additional Types

• In addition to a standard NPK fertilizer, orange trees also should receive one application of chelated iron per year and a single application of nutritional spray on the leaves.