Beautiful plumeria! I will try to answer your questions:

1. Will the three existing branches continue to bloom or form new branches if I cut them about half way down?

Once a branch blooms (forms an inflorescence or inflo) it will bloom until all the buds are bloomed out on that inflo. There are a finite number.

But at the point where the inflo forms, 1 to 4 new growth tips will appear. Each of these will continue to grow until they each will bloom. But each new growth may take several seasons before they are mature enough to bloom. They may get quite long before blooming -- in some varieties up to 2 or 3 feet. Much shorter in other varieties.

If you cut each branch halfway down, those branches will sprout 1 to maybe 3 new growing tips. Those tips likely won't bloom until their second full growing season (or longer). In other words, each new tip/branch will probably need to grow at least 18" long before it is mature enough to bloom. That's just what some varieties do in pots and in short growing seasons (zones 8 and colder).

2. When would be the best time and method for pruning?

If you decide you want to root the cuttings, I'd prune in April or so. That way your cuttings will be fresher and easier to root in early summer, which is when most people start cuttings. Otherwise, you could prune after the plant goes dormant, like in December. It will slowly start to regenerate tips over the winter. Those tips will then sprout out in late Spring or early Summer.

3. Can anyone tell me what kind of plumeria this is?

Nope. Don't assume it has a name if none came with it.

This post was edited by dave_in_nova on Mon, Aug 25, 14 at 9:51

As for your moving problem, it looks big enough to store over winter in a semi-bare root way.

If you trim off most of the leaves, then lift the tree out of the pot and shake a lot of the soil off, you can put the remaining root ball into a plastic bag and seal it.

Then you can carry the tree into the house horizontally, prop the tree in a corner over the winter and re-pot in the spring. It will need almost no water in winter if the bag stays sealed so the roots don't dry out completely.

Now if that tree gets much wider next season, I don't know what you can do other than prune :)

Thank you dave_in_nova and jandey!
One more question:
What happens to the inflo once it is done blooming? Does it just fall off? Should I trim it?
Thanks!
Kari

I have the same plumeria in Atlanta Ga. I got my first one in1995 or 96. It is a big grower, so I have cut it back so many times. When I take it (them) in during the winter, I cut off whatever won't fit through the door. It will bleed for a few hours, so be sure to protect your floor. One year, one of the trees was almost 15 foot by the time I needed to bring it in. I cut it back to about 6'. That was about 3 years ago. It is now over 9' and will probably have to cut it back this year too. I don't think you can over prune it, you might lose flowers for the next year, but it will still be a pretty amazing plant.

I have several Plumeria in pots but they have only one central trunk with several branches at the very top. I have to bring them inside for the winter as I live in Las Vegas, NV and it gets to cold in the winter. I have them in a mostly shaded spot and bury them in the ground outside in their pots for the hot 105+ weather for the summer. My problem is they are getting to tall to easily bring inside and then back outside but I am afraid if I just lop off the top to make it shorter the plant will die. Can someone please tell me the best way to make it shorter or do I just have to have it get taller and taller. If it had forks lower it would be easier but they are all right at the top which also makes it very top heavy.

Trish, I don't follow any of the 'common rules'. I prune when I need to, and have yet to have a problem. If it were mine, I'd cut the top off where you like the look and branching, and root that. I just finished rooting 3, and they did fine this time of year. The already rooted portion will regrow too. If you have any questions about rooting the cuttings, just ask. :)

I started water-rooting 14 cuttings back in March and April and only lost one out of the whole bunch. Water-rooting is almost foolproof, and can be done any time of the year. It also makes the plant more water tolerant from the beginning.

I've never tried water rooting for plumeria, but I've not had any failures out of the eight this year. Perhaps I've just been really lucky.