Where are you located? Plumerias are tropical plants and cannot tolerate temperatures lower than 35F for more than a couple of hours. Even in the 40's you will experience browning and leaf drop.

Bring it inside and keep in a bright, warm and draft free location. And hope for the best.

I am located in Oceanside, CA (San Diego) . So bring it in for the winter months? Do I need to do anything to help the plant? Or just bring it in and let it take its course naturally? Will the leaves fall off on their own or do I need to remove them? Thanks for you help I appreciate you!

Unless you are certain the temps will not drop below 40F, I'd bring it in. If the leaves are dead, they will fall off on their own. Otherwise, I'd treat the same as I would if outside

Just out of curiosity, what would I do if it was planted in ground and the temperature dropped below 40? How do I prepare for that situation? Thanks again for all your help. I hope you and yours a safe and healthy!

Dig it out, pot it, and bring it inside if it's outside and you're in a place where it gets cold. If it already got cold and froze...well, survival might be questionable, but it's worth a shot.

We wrap up and cover tender plants that can be damaged by a freeze. We just recently had a temperature drop in to the 30's. We covered my banana Magnolia tree to protect it. We did not cover the hibiscus trees because they are so big. They were damaged by the frost. They were damaged last winter too and they recovered after losing their leaves and they grew new leaves in the spring and were fabulous all summer. But if we were to get a hard hard freeze they probably would have been dead.

I cant imagine Oceanside getting that cold. I'm in Ventura. Occasional 38 degrees 1 block from beach. Old lonely socks from sock drawer work well on single tips once leaves are gone. I used to put up old sheets over them, then the wind did more damage with that than I think cold would have. When I first started I lost 3 Singapore Obtusas...too wet and cold wind when dormant.

My neighbor has one in a whiskey barrel which sits outside in heatwaves (over 100) and our occasional frost on the lawn weather. No overhead protection at all. It's fine, but it's a bigger plant than yours with a lot more soil around the roots. I'm in zone 10a. If you don't want to bring it in, put it under an eave or a more protected location.

Reese, great advice above for plans to care for your plumeria immediately....what part of Oceanside are you in? I know that area well and it is usually pretty temperate. However, I know there are little valleys and ravines where the cold air likes to sit. Jungle jacks’ greenhouses are just on the eastern border of Oceanside and it is a fine area to plant plumeria in ground come springtime.

-s

It looks like it got a bit of a frost on the leaves. Not the end of the world but needs to be watched. Check the branch tips to see if there is any damage. If so then you need to monitor it to ensure it does not start to rot. It is also possible to have frost damage along the branches themselves. It is something that also needs to be monitored. Another trick is to use incandescent Christmas Lights (pin or mini style) and drape all through the branches then cover with a frost blanket or old sheets. The pin lights give off enough heat to prevent any serious damage and are not hot enough to burn the plant. Larger screw in bulbs will burn the plant.

You must be in the very coldest part of Oceanside..just the name says "Never below 40f".

Just leave it. I haven't had frost in the bay area,and Celadine is shedding all its leaves..some red variety I got from Florida is still in leaf,Plumeria obtusa?..It could be a shrub by now if winters didn't always set it back. Too tender..but I have it and its 2' tall and wide..so it continues.

Also Reese,if its very dry ( and the photo looks like that) combined with cool nights? That might push dormancy on it faster than watered plants. In any case,just leave it and wait until it warms down there.