Plants not only need enough water and nutrients that they get from fertilizers, plants also need oxygen. But not only above ground, the roots must also get enough oxygen. And therefore have to Flower pots holes to have.
Unfortunately, this is not always the case. For example, in the clay pots that you like to stand on the terrace or spread out in the garden. These pots should not be set up without a drain. So it's best to pay attention to this when buying.
Drill a hole in the flowerpot yourself
Unfortunately, such pots are always offered without said holes. Then you have to help yourself. Turn the empty pot over and carefully drill a hole in it. This way the irrigation water can drain off, does not build up, the roots get air and the plant does not start to rot.
Alternative clay balls
You can put a coaster under the pot if, for example, you don't water every day. So the plant can use itself for a few more days. What you can alternatively do: Line the pot with foil and insert clay balls below, which store the water. Then the earth on it. But the variant with the hole is better.