rose of Sharon
槿 refers specifically to the rose of Sharon, a flowering shrub. Its meaning is narrow and botanical, without broader abstract extensions.
槿 combines 木 (tree/wood) with 堇, which likely contributes the sound. The character was created to name the specific plant.
The left side 木 is a tree, and the right side 堇 looks like a plant with a flower on top. Picture a woody shrub covered in rose-of-Sharon blossoms.
For キン, imagine a king (キン) admiring a rose of Sharon bush in his garden: king -> キン, and the royal flower is the 槿.