Do I need to take care of my frangipanis?

Not really. Once a frangipani is in the ground, it usually does better with no care compared to too much care. The danger of too much care is over watering. You should however learn what to look out for and monitor the condition of your frangipanis trees.

How will I know if my frangipanis are doing well or not?
The easiest way to confirm that your frangipani is healthy is to squeeze the branches. If the wood is firm, the frangipani is healthy. Also, in spring and summer, frangipanis should produce fresh green growth at the tips and lots of nice green leaves. There are many factors which can reduce the attractiveness of the crowns and leaves but the larger the frangipani, the less likely this will affect the health of the whole frangipani.