There are several ways to germinate plumeria seeds, I normally raise them in a mix in trays when doing bulk seeds but this is the method I use to check the viability of seeds from my pods or when I only want to grow up to a hundred or so. It is quick and easy and you can see exactly what they are doing.
I cut a piece of paper towel in half then spay it with a water bottle that has had H2O2 mixed into the water at a rate of 100 mls to 1 ltr (3 oz to qrt), next I start to place seeds that I have already peeled the wings and edges from onto it (pic 1). When I have the amount I want on it I fold the paper towel over the seeds and fold in the edges (pic 2) then I spray them again, hold them between my hands and gently squeeze any excess water from it. It is then placed into a plastic box with a lid to retain the moisture (pic 3), I keep the spray bottle beside them to spray again as necessary. I keep mine on the bench in our ensuite and you can do from one to several layers of seeds, in the pic below I have 4 layers(around 100 seeds). I check the seeds daily and if they are drying out I spay them again but remove the excess as it can cause rot if they are too wet, I also switch the positions of the layers.
Here in Thailand I get germination from 4 days onwards, once I see that they are germinating I will leave them for another couple of days so more can germinate then remove them from the box (pic 4) and open them up (pic 5). I do this where I have the seed raising mix ready in a tray so that it is easy to transfer them.
I make a hole in the mix for the seedling root and place the seed into it so that the husk rests on the top of the mix them lightly pack the mix around the root area (pic 6). This pic shows seeds planted up to a few days apart as the seeds that haven’t germinated are folded and placed back into the box then added to the tray as they in turn germinate. The tray in the pic has all the seeds from the 4 layers in it that did germinate. I water the germinated seeds in with a mixture of water and a seaweed solution or B1 or both plus again H2O2 at the same rate as the spray bottle. The seaweed/B1 de-stresses the seedlings plus helps with the root growth and the H202 kills off any fungal bacteria. I place the whole tray into a plastic bag(the ones from supermarkets are perfect) for the first 2 days as this will keep the moisture in the mix and also keep the husks/seed membranes soft so that they will come off a lot easier, make sure that they are not in direct sun but somewhere warm with light but sheltered from the elements.
Once the plastic bag is removed you can help remove any husks/membranes still on the seeds, they should just slip off very easily between your finger with a small amount of pressure. The seedlings will them start to green up (pic 7) after a couple of weeks and grow their true leaves, make sure they do not dry out, watering in the mornings if they need it is perfect. I move them outdoors at this stage too, somewhere they are still not in direct sunlight but are exposed to the elements, filtered sunlight is perfect for this. After 6 to 8 weeks (pic 8) they are big enough to transplant into individual pots.
Occasionally you may get a seed that will grow the root from the wing end of the seed or if you are lucky you may get a twin(pic 9), I let twins both get true leaves before gently separating them very gently or you can let them continue to entwine to become one plant but.