Here's an excerpt from The Color Of Your Thumb Has Nothing To Do With It that explains more about this short video.
So there you have it in a nutshell...why you don't have to empty saucers. I know some of you don't understand this, or don't believe it. Feel free to leave comments, ask questions, tell your own experiences.
The most important part of this arrangement is the liner, which in effect becomes the reservoir for the plant. Professional interior landscapers operate on a schedule, which requires the plants be serviced every week, every ten days, or every two weeks (for most reputable companies.) The liner must hold enough water to fill the plant's needs, making sure it doesn't get over-dry between waterings. However, there must also not be too much water - the plant has to be able to use all of the water in the liner well before the tech's next visit, thus reaching its ideal % of aeration.
If you understand the concept of liners and how they have been used in Interior Landscaping for over 50 years, you should understand that the emptying of saucers everytime you water your plants at home has now been proven to be unnecessary. Some people will surely say that their plants die if they don't empty the saucers; to them I would answer that the problem is not the little bit of water left in the saucer, but that they are neglecting to learn about the moisture level in the soil, at all levels, before they water.
Another problem with not emptying saucers, according to some home growers, is that emptying gets rid of unused minerals in the soil that are washed out with the water, thus preventing a build up of soluble salts. (More about minerals and salts a few pages down the line.) This problem is answered by not over-fertilizing. Plantscapers have found that fertilizing 1 - 4 times a year (depending on plant specie, light, size, etc.) is plenty for almost all plants. Again, you see, emptying saucers is an unnecessary waste of time.
Next time I'm going to talk about how to know when to water your plants, and how much to water when you finally get to pouring.
(by Marlie Graves)