The saucer, ancient object.
The stagnation of water in the vases, even worse in the saucers, create an unhealthy environment, where germs and bacteria multiply, attacking the plant and creating an environment that can become fertile "ground" for mosquitoes and the like!
This phenomenon can cause various diseases to plants and, in some cases, can cause them to die prematurely.
The most practical and healthiest solution is certainly to have instead of the traditional saucer a drainage inside the pot with a water reserve, paying only a minimum of attention not to wet the plant too much.
If this choice is certainly the best for indoor plants (also because you don't risk throwing away a beautiful walnut piece of furniture), for those left in the garden or on the terrace the choice becomes more complicated.
Outdoors, the pots risk getting a lot of rain and, in the event that they 'flood', having no drainage holes it becomes almost impossible to remove the excess water. However, there are jars with a cap (usually hermetic) which can be opened when needed and which causes the excess water to drain above the level of the reserve. La Casa delle Piante has for sale a line of 100% recycled Teraplast pots called Hoops and Capri which, in all sizes and colors, has this practical and innovative system for those wishing to say goodbye to the saucer.