Why do leaves turn yellow on my African Violet plants and how to prevent it? The main reasons...

Why do leaves turn yellow on my African Violet plants and how to prevent it? The main reasons...
African Violet flowers can have different color patterns, these include two-tone, bi-color, multi-color, geneva, dark eye, white, eye,...
There are different African Violet flower shapes, these include single, semi-double, double, frilled, fluted, star, wasp and cup....