I have a Dracaena Marginata. It was a very small plant 5 years ago.
It is now 3 feet tall and has never had direct sun, but indirect
bright light. During that time it has been transplanted three times.
I water it twice a month--keep it mostly on the dry side. They do not
like cold. Check for insect damage and inspect the root system--if
these are okay, give it a shower to clean the leaves.