These amounts are for an entire year--do not apply all at once!  If you are applying large amounts to mature trees, it is best to apply only one-third of the total amount at a time in the outer area of the citrus water basin to reduce the chance of "Burning" with the fertilizer.   Do this in March, June, and September.  For those of you gone during our long, hot summer, apply in only one-fifth increments in each of the following months: January, February, March, April, and late October.

On any fertilizer package the nutrients are listed as a series of three numbers which indicate the percentage of nitrogen, phosphate, and potassium.  Ammonium Sulfate 21-0-0 and Urea 45-0-0 are nitrogen only fertilizers, but a complete fertilizer like 16-8-4 could also be used.

Since nitrogen is the element most lacking in our soil, the amount of fertilizer to use is calculated from the fertilizer analysis.  The higher the nitrogen content, the smaller the amount of fertilizer necessary to get the job done.  For 16-8-4, it takes 6.25 pounds to equal 1 pound of actual nitrogen.  For 21-0-0, it takes 5 pounds to equal 1 pound of actual nitrogen.  For 45-0-0, it takes only 2.2 pounds to equal 1 pound of actual nitrogen.

Regardless of the age when planted, citrus is only considered mature when it has been planted for longer than 4 years.  Increase your well size as your trees grow. Follow each fertilization with a good irrigation.

Mature Citrus:         

Grapefruit/Pummelos - 1 pound of actual nitrogen per year.

	6.25 pounds of 16-8-4
	5 pounds of 21-0-0
	2.2 pounds of 45-0-0

Oranges, Tangerines, and Tangelos - 1.5 - 2 pounds of actual nitrogen per year.

	9 - 12.5 pounds of 16-8-4
	7.5 - 10 pounds of 21-0-0
	3.1 - 4.4 pounds of 45-0-0

Lemons/Limes - 2 to 2.5 pounds of actual nitrogen per year.

	12.5 - 15.75 pounds of 16-8-4
	10 - 12.5 pounds of 21-0-0
	4.4 - 5.5 pounds of 45-0-0

Immature Citrus (15 gallon plants):

	Go easy on the fertilizer.
	1st year - 1 -2 tablespoons twice a year (16-8-4).
	2nd year - 2 -4 tablespoons twice a year (16-8-4).
	3rd year - 1/2 pound of actual nitrogen/year (1 cup of 21-0-0, five times a year).
	4th year - considered a mature tree, use mature citrus guidelines.

Greenfield Citrus Nursery
John P. Babiarz and Debra L. Hodson, Arizona Growers Since 1972
2558 E. Lehi Rd., Mesa, AZ. 85213-9711
(480) 830-8000   FAX: (480) 833-5705
Summer hours Mon-Sat: 6am-3pm    Sun: closed

Winter hours Mon-Sat: 7am-3pm    Sun: closed