Gloxinia (Sinningia spp.), also called florist's gloxinia, is a tuberous plant in the same family as the African violet. Gloxinia got its name after being initially assigned to the Gloxinia genus; it was later reassigned to the Sinningia genus, although the name "gloxinia" stuck. It was first found in Brazil in 1785. According to NDSU's Extension Service, gloxinia blooms have short lives indoors, although it is possible to have the plant rebloom in subsequent years.
Place the plant in an area where it will get bright but indirect sunlight; do not expose it to direct sunlight. The potting mix should be well draining; a sand and peat mixture works well. Keep the area temperature between 18.3 to 23.8 degrees C.
Rest the plant pot on a layer of pebbles covered with water, if you're growing the plant indoors. According to NDSU, the water will provide humidity for the plant; you can also use a humidifier, however, NDSU advises to not mist the leaves or get them wet.
Water the plant at least twice a week, and every other day if need be, enough to keep the soil moist. Give the plant enough water so all of the soil is moist, not just the top layer. If the gloxinia is in a pot and not the ground, add water until it begins to drain out from the pot. At that point, drain the bottom dish of the standing water. Do not overwater, as this can rot the tuber. Again, don't get the leaves wet; the University of Missouri Extension says to "taper off" on watering as the gloxinia begins to go dormant.
Add fertiliser every two weeks when the plant is growing; do not fertilise when the plant is dormant over the winter. Use a fertiliser meant for flowering houseplants and follow the directions on the package. Do not overfertilize.
Watch the plant for signs of disease or pests. Gloxinias are subject to forms of blight and rot, as well as viruses. Mites, nematodes, spider mites and thrips are among the pests that attack the plant.
According to Iowa State University Extension, after the gloxinia is done flowering, it will become dormant. Let the tuber dry for one to four months in a cool (10.0 to 15.5 degrees C) room and then replant it in new soil. NDSU advises trying to repot it indoors in February. When watering any houseplant, keep in mind this explanation from Washington State University's Cooperative Extension: "The soil particles hold a certain amount of water too firmly for the plants to take. The water supply available to plants is water in excess of that required to satisfy the soil itself."