These days there is an abundance of fertilizers and additives you can use on your frangipani to improve their health and their growth. At the heart of them is the N.P.K or the nitrogen(N), phosporus(P) and potassium(K), nitrogen is needed for strong stems and folliage, ie, green growth and needs to be higher for seedlings as they need the extra growth factor when young. Phosphorus is for healthy roots, flowers plus seeds then there is potassium, it is very important for the health and disease resistance. These two are needed more as the frangipani grows and is into its 3rd season, you need to go from an even or slighly higher N fertilizer to one that has higher P.K values to boost them for flowering. You also need to insure that micro-nutrients/trace elements are fed to the frangipani as without these you can get plants that do not do as good as they should, these elements include sulphur, calcium, magnesium, iron, molybdenum plus various vitamins etc.
Slow release fertilizers are great for a seasonal feed, you can get varying lasting times with these as well, from a month to 6 months with 3 months being the average and most commonly used. They come in all shapes and forms, my personal favourite is Organic Xtra from Queensland, it is a pelletized one and can be used with young plants as it does not burn them. At the farm in Ballina we noticed a huge difference in the plants after using it, we had much greater growth and the flower size as well as colour were amazing. It was spread around the plants in early spring, anymore feeds than this led too much green growth going into winter. For potted frangipani Osmocote seems to be the preferred one to use although there are others that are similar, a good one for flowering frangipani is orchid bloom mix or a fruiting and flowering fertilizer as these have a higher P.K in them.
Foliar feeding is also becoming more common with frangipani but I do not like to deliberately water the leaves as it can leed to complications(rust etc). I water frangipani at their roots and I will mix in various additives for different reasons. I like to use Seasol which is a liquid seaweed based fertilizer when I transplant/re-pot frangipani as it is a great de-stresser so is vitamin B if you can get hold of it, you can even add both to the watering can to use on sick or poor looking plants to try to give them a boost, this combination is just as good if not better than using Superthrive which I think personally is not a great product, tests done with it have shown it does not do much at all yet it is extremely pricey to buy. There are several water soluble fertiizers on the market too but as I do not like to foliar feed I avoid them but it is a personal choice, you can always simply apply them to the plant at ground level. I have done this as well as use a slow release to give the plant a boost, it does not harm them as long as it is not done often.
I have mentioned micro-nutrients and trace elements above, it is a good idea to use them at least once a year as it does help the plants take in more of what they need, especially potted ones, you can get it in powdered form so you just add it to your watering can. If your leaves are doing strange things or changing colours(not close to winter) a dose of trace elements will usually fix them up.