Don't fertilize more than 3 times a year. Actually, twice a year - March and October - is enough. Those "dates" are not an edible fruit, they are the seeds from the Queen Palms. And not fertilizing is not going to stop them from blooming and throwing seeds; it may eventually kill the palms, but nature makes them bloom regardless.

lesco 8-10-10 works great. pricey, but it works. twice a year here...store brands stink....

Palms are not true trees and require different fertilizer on a different schedule.
Please read these two documents for valuable information. Here are a few sentences to give you an idea:

Research at the University of Florida has shown that regular use of a fertilizer having an analysis (=the three numbers on all fertilizer labels which refer to their N-P2O5-K2O content) of 8N-2P2O5-12K2O +4Mg with micronutrients can correct mild to moderate deficiencies and prevent their recurrence in most soil types in south and central Florida. However, not all fertilizers having an analysis of 8N-2P2O5-12K2O+4Mg with micronutrients are effective, and if improperly formulated, may be worse for palm health than no fertilizer at all.

Chemical symbols are: N=nitrogen, P=phosphorus, K=potassium, Mg=magnesium, Ca=calcium, Mn=manganese, Fe=iron, B=boron, Cu=copper, Zn=zinc

High N fertilizers applied to turfgrass even 30 feet away from a palm on one side only have been known to kill palms from induced K deficiency.

2 links address palm fertilizing : http://edis.ifas.ufl.edu/ep273
Nutrient Deficiencies of Landscape and Field-grown Palms in Florida

and the link below:

Here is a link that might be useful: Fertilization of Field-grown and Landscape Palms in Florida