Mimic nature and feed your plants a little bit each time you water.
Little plastic net baskets with a hinged lid on a spike. Fill with time-release fertilizer pellets, oyster shell, or any slow release amendment and put them in hanging baskets, or at the top of mounted plants (where the food pellets would fall through if applied loose).
Available in 3 basket sizes:
Small (penny), Med (nickel), or Large (quarter)