Q.African violets
My beautiful AV is dying and I’ve done everything I know to do. It was happy until winter. Also, the outside of the pot has developed a white substance like flaky dried toothpaste. What is that? This is a self-watering pot. I plan to re-pot today and see what happens.
The build up on the outside of your pot or the soil surface is likely excess salts; either from conditioned water or over fertilizing.
Use distilled water for your African Violets.
Here is an article to refresh you on the care requirements.
https://www.gardeningknowhow.com/houseplants/african-violet/african-violet-care.htm