Rose of Sharon Planted for 2 1/2 Years, No blooms
I have had a rose of Sharon planted for two and a half years that still has no blooms.
It might be the age of the plant, or one of several environmental factors. This article should help: (and yes, it's about hydrangeas, but this goes for althea as well!) https://www.gardeningknowhow.com/edible/fruits/lemons/learn-about-fertilizer-for-a-lemon-tree.htm