I read that you can plant a Cassia Golden Shower in a pot. How big a pot and how big can the Cassia get?
Planting Cassia in Pot
Certified GKH Gardening Expert
I did a bit of research and from my findings it is not recommended to grow this species in a container.
Planting in the ground is recommended.
You may want to choose another type of tree for a container or patio tree.
Make sure you check your growing zone and verify the growing conditions in your garden.
Here is a link to help you determine your growing zone.