Dragon tree plant dying?

Question

Brand new to this world but hoping someone can help :) I’ve had this dragon tree plant in my bathroom for around a year. Checked the roots about 6 weeks ago and noticed they were starting to grow through the pot so I reported into a bigger plant pot. Sadly over the last few days the leaves on the taller part have all turned yellow and fallen off, but the Lower plant seems ok! The stems have gone almost spongey too, rather than solid. (Since the photos below, all the leaves have now dropped off)

EDIT adding some detail in response to the comment below! So the larger plant is around 70cm high, smaller is 40cm. The pot is around 30cm high and 30cm diameter. I water it thoroughly maybe every 3-4 weeks when the soil feels dry, plenty of drainage but no gravel in the pot. Occasionally use a few drops of baby bio plant food.

Is there any way to salvage the bigger plant? It’s not a very bright room so I’ve moved to a sunnier spot. I don’t water often as it always seemed fine and understand I need to let the soil dry between watering. But if there's no hope, I may take it out to give the smaller plant a better chance and more room.

Thanks in advance!

Answer 1

The yellow leaves in the first picture are a sign of root rot. Usually this is caused by overwatering or too wet soil. In your case, when you say it was doing good for a year, and it started after repotting, my guess is that something has changed that caused the soil to stay longer wet than before. This could be due to a larger container, or to the soil which is used. If the container is too large, it stays longer wet because the plant can only take up a certain amount of water and the rest has to evaporate (which takes longer with a larger container). It can also be that previously you had better drainage capacity in the soil. You might want to add some grit or perlite to the soil to improve the drainage.

I would also advice to prune the soft rotting parts above ground. Try to cut back where the canes still look healthy. The rot may spread if you keep it.