General growing advices for gesneriads
The soil should be airy, large grained and well drained. Preferably use topsoil mixed with leca balls. The soil could also be mixed with soil improvements like perlit or vermiculit.
Most gesneriads have thin root threads and does not approve of standing in water. The most common death reason as a matter of fact is overwatering. Extra caution is needed concerning bumps and rhizomes who have not yet wakened from their rest. Always use temperated water, since the plants easily could get brown cold damages if the water is too cold. Do not water Chirita, African Violets and Streptocarpus until the soil feels dry. Other families, for example Copperleafs need a more regular supply of water and a higher humidity. If the plants get brown, dry tips on the leaves, the reason is often that the air is too warm and dry. Remember that the need of water differs a lot over the year and depending of the temperature in the surroundings.
The best tip is to always touch the soil before watering!
Most gesneriads are happy to be placed in a bright east or west window. Avoid places in broiling sunlight. If the leaves of for example African Violets get yellow-bleached, the reason is often that the plats have got too much sunlight. It is also possible to grow gesneriads under fluorescent lamps. Use common fluorescent lamps that for example can be fitted in a light garden. The lamps should be turned on for 12 hours per day. Many gesneriads tolerate stronger light than the African Violets and some extreme shade loving plants do better with weaker. In a light garden you are able to give different plants different amounts of light with the same lighting. It is shadier on the edges of the shelves and inside a mini-greenhouse (the transparency of the lids is reduced greatly with age). In a light garden, the most light is in the center.
Sinningias and other plants who grow very high if they get less light than they need, could need to be placed only 10-15 centimeters from the lamp. As a rule of thumb to estimate if the distance is adequate, you can hold your fingers just beneath the lamp. If the shadow falling at the leaves is blurred and hard difficult to see, the lamp is too distant to grow flowers who need lots of light to grow compact or to blossom (like Sinningia, Fool's hood and African Violet).
The average gesneriad is happy with 25 degrees Celsius during the day and 20 degrees Celsius at night. Avoid exposing the for drafts, certain ones are very sensitive. Only alpines survive freezing. Temperatures above 30 degrees Celsius make some gesneriads thrive. Others will collapse by the heat. Streptocarpus and many Chiritas want cooler temperatures during the winter. If you have the possibility to let your Streptocarpus spend the winter in a bright and cool place (preferable 10-15 degrees Celsius) you can expect a sumptuous flowering in the Spring. Many Streptocarpus die during the winter if you try to let them spent the winter in a window with a hot radiator below.
Most gesneriads have sensitive roots and do not tolerate high salt content.
Water only with very dilute nutrient solutions.
NEVER FORGET THAT THIS IS THE "FAMILY JUST RIGHT"!
The association has published a written paper of 40 pages where you can find detailed growing advices and many practical tips about growing and breedingof gesneriads. The paper can be ordered by paying 40 Swedish crowns to the post giro account of the Gesneriasts, 921 94 22-4. Do not forget to write that it concerns growing advices!