Master gardener Paul James offers two reasons why he prefers to leave saucers behind:
Saucers collect water that can quickly become a breeding ground for mosquitoes. The vast majority of plants prefer to be watered from the top down rather than wick the water up from below. When you add water to the top of a container, the weight of the water drives oxygen and other gases down and out the drainage holes. As the excess water drains out of the container, spaces open up between particles in the potting mix. Air rushes in to fill the spaces in the potting mix and in the process, charges the mix with fresh oxygen and invigorates all the microorganisms that help make nutrients available to plant roots. As the surface of the container dries, the surface of the potting mix tries to pull moisture up from the bottom of the pot, but rarely does it make it all the way up. So if you water from the bottom or if you use a saucer and allow it to remain full of water, you never really flush the system, and that can lead to an accumulation of salt deposits on the container wall, especially if you use a lot of high nitrogen, synthetic fertilizers. "So I tend to skip the use of saucers," James says, "and I think my plants are healthier as a result."
