Keep gloxinia moist, but not drenched, with tepid water that has been left to sit for a few minutes if it's from your tap. Some gloxinia fanciers use rainwater or distilled water. Allow the surface of the soil to dry slightly before watering.
Water gloxinia from below by placing it in a pan of water and allowing the water to filter up towards the surface of the soil. When it feels damp, remove the plant and set it in a dish filled with water and pebbles that keep the plant above the water while giving it the humidity it needs.
Stop watering your plant when the blooms die off and the leaves begin to turn brown. Gloxinia need a dormancy period of six to nine weeks at a temperature of 50 degrees Fahrenheit. When small shoots begin to appear, re-pot the tuber in fresh soil and resume watering.