magnesium all slow release, never lawn fertilizer in palm drip line fert grass with palm fert. The general application rate for palms is 1.5 lbs. per 100 sq. ft. of canopy every 3 months. The formulation recommended for palm trees for this application is 8N-2P-12K+4Mg. Fertilize between the months of March and September
http://sumter.ifas.ufl.edu/FFL/documents/PalmFactSheet.pdf
Citrus 10-10-10 some say 6-6-6
Young Trees
Citrus trees will need more fertilizer as they age. In humid tropical climates such as Florida during the first year, start applying fertilizer at the start of the growing season in February just as the buds begin to swell, and reapply every six weeks through October. Apply about 1/2 pound of 10-10-10 fertilizer per tree. In the second year, apply about 1 pound per tree every seven weeks. For the third year, apply 2 pounds per tree every nine weeks. In the fourth year apply 3 pounds per tree every 12 weeks.
Mature Trees
For mature citrus trees that are 5 years old and older in humid climates, fertilize three times a season with 5 pounds of 10-10-10 fertilizer per tree. Fertilize in February, May and November. For each application, apply 1 pound of fertilizer for each year of the tree’s age. For instance, a Florida tree 10 years old would get 10 pounds of 10-10-10 fertilizer in three separate applications for a total of 30 pounds per year.
http://homeguides.sfgate.com/fertilizing-cycles-citrus-trees-22781.html
