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Any chance you had a frost?

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Where in So Cal are you? Its probably transplant shock accompanied by the fact that its the time of year when plumies go dormant and the leaves drop off. I have a friend in zone 10 in the south bay that moved and dug up his plumies that were in ground and replanted them to their new property, his leaves are doing the same thing as your plumie. If your not in zone 10 then it may be cold damage or frost damage as I know inland areas of So Cal have had frost warnings over the past month at night.
Good Luck

Thanks for the reply, I'm on the coast in Orange County about a mile from the water. We have had some low 30's nights as of late. I'm wondering if there is anything I can do to mitigate the damage either with fertilizer or something else.

I am in Riverside and have been monitoring a row of about 5 foot tall plumies planted in a wind-exposed yard on the way to work. They look about the same or a bit worse, all the leaves on the top foot or so of all the plants are brown and shriveled. We did have temperatures down to 31 degrees this last few weeks. Perhaps you should consider getting some frost cloth and covering it.

Gchap,
I am assuming your plumie was rooted and in a pot pre-tranplanting? If your plumie was full rooted with no to minimum root ball damage from transplanting I would leave it be as it is the Dormant season. I would cut off the leaves and look at it as sculptural garden art. When a plant goes dormant it really does not absorb that much moisture or nutrients like it does when its actively growing. According to Luc and a few other growers, dormant plumies supposedly takes up a min amount of nutrients but not much.

If you try to fertilize your plant you may damage it as it will not use the nutrients and the fertilizer can burn the root system. Just leave the plant alone and come April or May you will should see some growth. Hope this helps.

Cheers

While it won't help for any possible cold damage done up until this point, I second the frost cloth suggestion. I'm in the inland empire, and have 6 in-ground plumeria in the back yard. They've been covered with frost cloth since the first cold spell, and it seems to be working. I didn't do the frost cloth thing last winter until too late, and ended up having to amputate several branches of one of the plumeria the following spring to save it from rot.

I don't do anything really fancy - I just buy the long garden stakes at Lowes (6'ish) and stick them in the ground around the plumeria, then throw the frost cloth (also from Lowes) on top and secure it with clothespins. The cloth should touch the ground on all sides. The plumies still get some airflow and light, but the cloth keeps it slightly warmer underneath.

I agree with everyone else that you should probably leave it alone (just protect it from future cold spells). Keep an eye on any branches that you think might have damage, though, and if they start feeling mushy, you may need to take action.

I also live along the coast in Orange County about 2 miles from the ocean and we have not had any freezes so far this winter. A few instances of hoarfrost which develops on some surfaces even though the air temperature does not hit the freezing mark, but those are not the same as a freeze and I would not think that would damage a plumeria. I don't think we have experienced a true freeze where I am since 2007.

I only have a single Samoan Fluff and one Divine that have not dropped leaves yet, and neither was impacted by the hoarfrost even though the grass in front of them was dusted white with frost crystals.

I would guess your situation is simply a combination of transplant shock and the normal process of dormancy. I wouldn't waste money and energy on frost cloth or anything else, just wait for dormancy to end in a few months and I suspect your plant will come back without any issues.

Is there anything you can do to help with transplant shock?

During the GROWING SEASON you can use Supertrhive or B1 can help but since its dormant season for the plumies its really not going be able to assimilate either. Your plumie is basically going dormant/sleeping till April. Id just leave it be and watch the amount or water it gets, rain is ok for it.

You might want to consider cutting off all the leaves and just let it do its thing which is to go dormant. Just again watch the watering and as long as your branches and tips stay firm your plumie is ok. Do not fertilize your plumie as you may cause chemical burns to the root ball.