Q.What Is Causing Lower Leaves Of Red Button Ginger To Turn Yellow and Die?
My 11 year old grandson discovered this plant in Hawaii & wanted Gran to grow one. Ours has been doing fine, in Seattle area, indoors in a container. Our plant is about 8 inches tall but bottom leaves are turning yellow. What is it and how can we (I) treat it? We appreciate your help. Thank you.

Certified GKH Gardening Expert
Those are not the culinary gingers but are called spiral gingers. Often, yellowing leaves indicates over or under watering. I suspect overwatering. Let the plant dry out a bit between waterings.
These articles should help:
https://gardeningsolutions.ifas.ufl.edu/plants/ornamentals/spiral-gingers.html
https://www.gardeningknowhow.com/plant-problems/environmental/plant-leaves-turn-yellow.htm