Q.bottle brushes only have leaves on top
My bottle brush plants are bare on the bottom but about 3/4 up have leaves. What would cause this? Could it not be getting enough sun?
It is possible that you actually have a variety of Bottlebrush that is a tree instead of a shrub genus.
Many people prune the Bottlebrush to be a tree form and have a single trunk.
You may be doing nothing wrong and the plant just growing to it's natural state.
Here is a link to refresh you on the care requirements.
https://www.gardeningknowhow.com/ornamental/shrubs/bottlebrush/growing-bottlebrush-plants.htm