Hello everyone!
First timer here. I have a 3 year old plumeria plant that I have been growing indoors with sun lamps in Washington. It's growth is very slow given the limited sun and warmth WA has here, but its managed to stay alive so well all these years! During the summer, it will be placed outside and have lots of leafy growth. Once fall hits, it's brought inside but will always stayed firm throughout the winter with a handful of leaves still on.
About 2 weeks ago, I noticed the section where the only two branches emerged from became soft (pics below). I was worried for stem rot, but have been given little water (once every 10 days or so) due to winter approaching and assuming dormancy was going to happen. But then, the branches started to shrivel, the softness spread and all the leaves became droopy (usually only the ones furthest from the tips would slowly turn yellow and fall off). Plant continued to go down hill, and I cut one arm off to check for stem rot. Inside I didn't see any brown but I noticed the stem had a partial hollowness. The other arm is also still soft and the main stem near the branch is partial soft. Any idea on what could have causes this? Should I cut the stem until it is no longer soft? I'm mainly interested in saving the plant and don't mind cutting off more if it means the stem will live another day to sprout new branches.
The main base near the soil line is still firm, so I'm not sure if I cut off the arm in vain and my plant is actually fine.
I have three other plumeria nearby that are fine, so I have a low suspicious for pests.
(One photo shows all my plumerias, but the one Im asking about is on the right in the leaf patterned pot. That photo was taken two months ago just to show how much it booms during the summer.)
