I'm going to guess that there's a smaller container inside the teacup- one that does have drainage; since the build-up of salts is probably not going to be good for the plants in the long run?

Tami Sue, Mini and semi minature african violets need smaller pots than a tea cup. African violets should be in a pot 1/3 the size of plant. I have set them planted in small pots in tea cups by either filling bottom of tea cup with gravel for drainage, making sure water in gravel is below bottom of pot. Another way I have done it is by cutting the bottom of a solo cup off ( about 1 to 1 1/2 inch) and turning this piece of solo cup over to raise my small cup to height of top of tea cup. I plant semi minatures in solo cups and mini's in empty Keurig cups (from my coffee maker).With the plant sitting on the turned over solo bottom, I am also able to hang a wick into water at a level below bottom of pot into water in bottom tea cup to wick water. Hope this is a help.
t

"With the plant sitting on the turned over solo bottom, I am also able to hang a wick into water at a level below bottom of pot into water in bottom tea cup to wick water"

What a great idea. I have lots of cache pots and now I can use them for my violets when they are blooming. The violets are growing under lights and when they bloom, I like to place the around the house to enjoy them.
Thanks for the info.

Your welcome, I also sometimes use the little plastic containers that take out restaurants use for sauces.Many are small enough to fit into the bottom of a cup.
T

If you decide to use the tea cup as a temporary pot for a violet, fill the bottom with pebbles or perlite--about an inch. When the plant begins to look "off" take it out of the tea cup and plant into plastic pot.

Nancy