I would use the jobes for ferns and palms instead if you are going that route. Better ratio..less phosphorus. What I would do intead, though, is PM off-ice.. a member of Plantgeeks.com amongst other boards... and see about getting his root fertilizer tablets. I think they're $1 for 12. Jobe spikes will keep some plants alive, but in my opinion, they're too simplistic to promote the growth so many of us seek. I've used off-ice's homemade tablets, seachems tablets, jobes for ferns and palms,Aquarium Pharmacuetical's tablets, and jobes for household plants, and that is in order from best growth and results to worse growth and results, in my experience.
"Good judgment is the result of experience, experience is the result of bad judgment." --Mark Twain