Fertilizer spikes of any kind are pretty useless :-) That formulation is pretty good for pumpkins, so you could grind them up and apply like a typical granular fert. For best fruit/produce production, you want a fert that has a lower first number (nitrogen), so that would eliminate the fish or the MG. And since Gardens Alive declines to disclose the NPK of their products, I'd avoid them on general principals - you need to know the NPK in order to provide the proper ratio of nutrients.