Generally speaking, it's better to water plants from the top than it is to subirrigate. Subirrigation is the process of watering plants by placing pots in a shallow amount of water in a tray or saucer, and allowing the soil to draw water up from the bottom via wicking action. It's acceptable to periodically water subirrigated plants to leach soluble salts from the potting soil.
However, avoid allowing the pot to sit in water for an extended period. This waterlogs the bottom of the pot, which causes root problems. An easy way to extract excess water from a saucer beneath the pot is to use a turkey baster.
For more information, please see the PlantTalk script #1318, Houseplants: watering.
