Prism99

For fertilizer, I like Osmocote or similar bead types. It's easy to see what you've added, and they last 6 to 9 months or so. You are pretty safe if you add this fertilizer only in the spring. Aside from measuring fertilizer according to package instructions, I also go by the visual look. The jar usually has a picture showing how far apart the granules should be. If in doubt, add a little less fertilizer. If later on you have any suspicion that you have added too much fertilizer, you can remove some of the beads.

Repotting helps too. Fertilizing is definitely necessary if they stay in the same pot.