Thoroughly wet your tillandsia 2-3 times per week; more often in a hot, dry environment; less often in a cool, humid one. In conditions of extreme drying and consequent moisture loss, air plants cannot get replacement water from their roots like a terrestrial plant, or draw on internal reserves like a succulent.
After watering, plants should be given enough light and air circulation to dry in no longer than 4 hours. Wind can be a detriment, as it can make the plant dry too quickly. Remember that window fans can cause the plant to dry quickly as well. If the plant dries within a very short period of time it does not have the chance to re-hydrate at all.
Spray misting is insufficient as the sole means of watering but may be beneficial between regular waterings in dry climates to increase the humidity around the plant.
If the plant is in a shell, be sure to empty the water out. Tillandsias will not survive in standing water.
Under-watering is evidenced by an exaggerating of the natural concave curve of each leaf, or drying at the tips. Overwatering can quickly lead to rot, and the central rosette will become mushy and disintegrate.
One last thing about watering your air plant: It is much better to water in the morning than at night. Air plants absorb the carbon dioxide from the air at night instead of during the daytime. If the plant is wet, it does not breath, therefore, unless it can dry quickly at night, plan on giving morning baths.
Following each watering, Tillandsias should be given enough light and air circulation to dry in 4 hours or less. Do not keep plants constantly wet or moist.
Do not allow to dry too quickly though. 1-3 hours is optimum.
Optimum temperature range for Tillandsias is 50 - 90 degrees F.