At the Illinois show, Dale Martens asked what fertilizer I use after a compliment on my healthy-looking leaves. At the time, the only thing I could think of was Peter’s, which I use frequently. (But it’s only one of several I use in rotation, especially before a show. The one most likely responsible for healthy green leaves is Dyna-Gro Foliage Pro, which I use in rotation with Bloom Plus before a show.)
We’re always told to feed our violets, and we definitely should or we won’t see many flowers. But use common sense. Too much of a good thing is not a better thing. A very light, but regular feeding should be given to violets with a short break of plain water every 4-5 weeks (again, this is my opinion.) Since I wick water now, I generally refill my reservoirs twice with fertilized water. Then, I leach out each pot and fill the reservoirs about half way with plain water. When that is used, I resume feeding.
Here is a short list of the most common fertilizers I regularly use:
Peters African Violet 12-36-14
Miracle Grow African violet 7-7-7
Dyna Gro Foliage Pro 9-3-6
Schultz Bloom Plus 10-60-10
I also occasionally use Bounty, Schultz brand African violet fertilizer (which also has urea in it,) and regular Miracle Grow (non-African violet type.)
When used sparingly, I think most fertilizers are safe. Just keep in mind that African violets have very delicate roots and cannot handle a lot of fertilizer. Also, remember to never fertilize your violets if the soil is dry. When allowed to dry, some of the tiny feeder roots will die off, making the main roots especially susceptible to burning from fertilizers.
Hope this helps! Keep growing. :-)