What to do when you have extreme dry or wet conditions
There are many factors that affect the amount of moisture that a plant needs and gets. Some plants do well with more moisture in the air, such as the dew-loving redwoods of the Pacific Coast. Other plants do well in drier conditions, like cacti. Each plant is adapted to its specific native environment and it is important to note its moisture requirements before planting.
Sunlight affects moisture. It provides energy that evaporates water from within soil and from within plants (by the stomata on the bottom of the leaves). Too much sun, not enough water will make a plant dry out - (it doesn't take a rocket scientist).
Too much moisture (too much rain, dew, or water from the hose) can waterlog a plant's roots and "drown" the plant. Depending on location, too much moisture can lead to rotted leaves and roots.
Water your plants when they are dry to about one inch under the topsoil. Don't let them dry out completely for months. Don't waterlog them. Spritz plants with a fine water mist to keep dust off and provide them with a bit more water. Sometimes a steamy bathroom works well to provide needed moisture.