Florist gloxinia (Sinningia speciosa) grows from a root tuber and enjoys widespread popularity as a flowering gift plant or house plant to grow alongside African violets and ferns. In frost-free gardens with dry winters, the gloxinia makes a lovely woodland plant or patio container specimen. This perennial with frilly bell-shaped flowers relishes high humidity but not hot tropical temperatures.
Florist gloxinias prefer bright, indirect light or filtered light through a screen in homes, and outdoors, dappled shade exposure under non-deciduous trees or latticed arbors. Early morning or evening sunlight does not harm the foliage.
People who buy and plant florist gloxinia from dormant tuber roots need to sow them in moist but well-draining soil types. In containers, use a soil-less medium comprising peat and perlite while in outdoor garden soils, choose one that has a slightly acidic or neutral pH (6.0 to 7.0)--ideally a sandy soil with a lot of organic matter such as compost incorporated.
When actively growing, the gloxinia needs moderate water; the soil should remain evenly moist but never soggy or dry. Half-strength doses of a liquid fertilizer may substitute for a regular watering every two weeks. Do not fertilize in winter or when plants remain dormant. Choose a quality fertilizer that contains potash in large quantities, or reveals a high potassium number on the product label. Potassium (K) is the third number in the common three-numbered fertilizer formula ratio.
Although a tropical plant, florist gloxinia falters when temperatures drop too low and when when high. Ideally, a growing environment free from drafts that ranges in temperature of 60 to 75 degrees Fahrenheit results in beautiful foliage and flowering. In addition, high humidity ensures leaves do not abort or display dry browned edges. Low humidity also causes young emerging flower buds to dry and abort. Increase humidity indoors by grouping plants or by resting pots atop pebbles in a tray will with shallow water.
If properly sited in the correct light, temperature and humidity, florist gloxinias should not develop any dire pest or disease problems. Monitor the plant for mites, aphids, whiteflies and thrips insect pests. Diseases to watch for include general plant viruses, soil nematodes and crown rot. A clean, tidy growing environment and use of fresh, sterile potting soils diminishes the chance of pests and diseases.
Remove spent flowers and yellowing leaves promptly. Decaying petals and rotting leaves can harbor insects and their eggs, as well as create conditions conducive for fungus. Avoid getting foliage wet when watering to prevent hard-water stains.