FERTILIZING CITRUS

By Linda Lewis Griffith

Citrus trees grow so well on the Central Coast that it's easy to take them for granted.  You may have a lemon tree on your patio or a tangelo that supplies the whole neighborhood with bags of sweet, tangy fruit.  Even hard-working citrus appreciate love now and again.  And you can do that by regularly feeding them. 

Citrus trees planted in the ground get most of their nutrients from the soil. The exception is adequate nitrogen.  Deficiencies in nitrogen reduce yields and adversely affect size, color, sweetness and peel texture of the fruit.

Nitrogen should be applied several times throughout the year.  The first feeding is in January or February, just prior to bloom. The second occurs in May.  The final feeding is in June. 

Select a nitrogen fertilizer, such as ammonium nitrate or urea.  Determine the size and needs of your particular plant and follow the instructions on the label.  For instance, a one-year-old year tree should get 1 tablespoon of nitrogen fertilizer three times per year.  As the tree matures, the application rate increases approximately one- tenth of a pound per year.  A five-year-old tree may require 1 pound of nitrogen fertilizer divided into three applications. 

Apply the fertilizer over the root area of the tree and at least 1 to 2 feet outside the drip line.  The fertilizer should be thoroughly incorporated into the soil.  Avoid feeding too late in the season as it may delay fruit coloring or make the rind tough.

Citrus grown in containers have slightly different needs.  Frequent watering leaches micronutrients out of the soil so they're often deficient in iron, zinc or manganese. To compensate, use a complete, slow-release fertilizer and follow the manufacturer's instructions.  Foliar sprays are also effective if applied in the spring when leaves are approaching their full size.

More information about fertilizing citrus is available through the University of California Division of Agriculture and National Resources website:

http://www.ipm.ucdavis.edu/PMG/GARDEN/FRUIT/CULTURAL/citfertilization.html.