Most any fertilizer with a high nitrogen and potassium level, and a low phosphorus level that also contains trace minerals would be an OK fertilizer for citrus. In the book "The Genus Citrus" under the chapter "Soil And Cultural Practices" it states that a fertilizer must be chosen that will replace the minerals, and their ratio, that are lost from a citrus orchard, by being taken up by the roots of the trees in the grove. It further states that citrus trees absorb nutrients in the ratio 5-1-3. Meaning that for every 5 parts nitrogen that the roots of a citrus tree absorbs from the soil, it will take up only one part phosphorus, and 3 parts potassium. Fertilizer must respect this ratio when the mineral content in the leaves is satisfactory. Obviously, in cases where the soil has an over dosage or a deficiency of one or more elements, this ratio must be changed to a more appropriate one. I use Jack's Pro High Performance 25-5-15 Fertilizer (a 5-1-3 ratio fertilizer) made by the J.R. Peter Company, because it has the perfect ratio of nutrients that citrus absorb. It has worked very well for me over the years. - Millet
