Plants that are native to arid, or desert, regions should dry out between waterings. They are susceptible to root rot in continuously moist soil. Beside sedums, succulents and cacti, many plants with very small leaves (often bluish-gray) fall into this category. Lavender and thyme are prime examples. Typically online sites will state that the soil should dry out between waterings. Self-watering just means a pot has a water reservoir in the bottom. If you don't water enough to fill this reservoir, and rain doesn't soak it, then you have a regular, though more expensive, pot. These pots have overflow channels but will fill the reservoir before overflowing. Keywords to look out for are a plant's preference for "fast or free-draining" soil or sandy soil. You might also see instructions to add sand to the potting soil mix.
