Any fertilizer suggestions for a semi-novice that tends to struggle with appropriate measurements?!?  I worry about not using enough but then also overdoing it!  Are the spikes any good?  I just moved to south Florida and have really taken advantage of it with my palm collection, but am limited to having them in pots for the foreseeable future.  Any (affordable and easy to find) recommendations would be greatly appreciated!

You can't go wrong with osmocote slow-release; you really can't overdo it, and it lasts for six months+. I'm assuming you're talking about relatively small palms in pots, here; with big, really vigorous palms, a liquid feed designed for palms would be more practical. But be very careful with liquid feeds if they are small, and dilute a lot.

I never feed seedlings, unless they're in a medium completely devoid of fine organic matter, in which case I only use osmocote.

I don't know what you're growing, but if you've just moved to Southern Florida, chances are you'll be able to plant out lots of them if you get the opportunity (unless you only grow palms from the Colombian cloudforest, etc.), so that is a different ballgame, and I defer to the millions of posters from Southern Florida on here on the other forum.

My measurements are pretty vague; it's like cooking, you just get a feel for how much is needed.

Carl Pool palm food