African violets not growing

[ceropegia]

A few months ago I purchased 3 standard violets from Rob's Violet Barn. They have grown very little since I got them. They each have about 4-6 leaves, since the greenhouse clips most of the leaves off to ship them. Each one has tiny new leaves in the center but they don't seem to be growing. I also got a free miniature violet with my order, and that one has grown well since I got it, though it hasn't flowered yet.

Right now I have them on the second shelf of my plant rack, which is about 23" away from my 2 T5s and underneath my large hybrid orchid pots. I prune the dead leaves, I water them when they dry out, etc...basically everything I'm supposed to do but still no growth. My rhizomatous begonias and other similar-condition plants, along with the mini violet, are growing very well, so I'm not sure why these violets haven't grown any.

Any suggestions?