One of most popular house plants over the last 60 or more years is the African violet. It can be grown in small containers suitable for the windowsill. It is easy to propagate from a single leaf a trait that was needed in its forest homeland. Originally there were less than a dozen species most of which were blue, but by careful selection, hybridizing and even chemical treatments there are now hundreds of varieties. When I first started growing them over 50 years ago I tried to get one of each color or type. That collection took up the top of the large buffet in our Northern Michigan home. 

Propagating them was fascinating. I would put a leaf stem in a cup of water, sit it on the windowsill and weeks later there would be a tiny plant growing at the base of the stem. That tiny plant would then be planted in a small pot in good potting soil and tended carefully until it grew into a large healthy flowering plant, then it would be given to someone else for their pleasure.

I learned a lot from those plants, they kept me occupied during the long snowy winters. They were generous with the flowers if I took proper care of them. If I neglected them they would get too dry and fade away. It wasn’t until many years later that I learned how to get them to set seed and how to grow them from seed.  

Holtkamp* nursery in Germany introduced a number of patented varieties which they named the Rhapsodie and later the Optimara series. These they had developed and brought to the American market. Some other growers have also taken up the broadening of the selections possible. Now there are flowers that are pink, double, edged, and yellow .  There are plants with variegated leaves, with crinkled or ruffled leaves, with small leaves, with large leaves. There are trailing plants with all colors of blooms. Holtkamp also sent some seed into earth orbit via the NASA space program. Those seeds were in orbit for seven years and now that they have returned they are being tested for mutations and new varieties are being developed. So if you can’t find exactly what you want just wait a while and someone will introduce one. Or better yet, try your own hand at growing and developing your own variety.  

It is a common belief that African Violets because they have hairy leaves should not be allowed to get wet but that is not always the case. Obviously, in the forests where they originated they would get wet without harm or they would have all disappeared long before man discovered them and brought them to Europe where they were introduced as greenhouse plants. Later they were adopted as house plants because of their low light requirements and ability to bloom for long periods if they were given enough light, moisture and fertility  

The problem with African Violet leaves getting wet is that cold water can chill the leaves and allow them to become subject to the fungus Pythium ultimum that penetrates the leaf surface and causes it to rot away. Or the center of the leaf rosette retains the water and causes that to die either from the cold or from the fungi. Hot water will also kill the leaf tissue so the logical middle way is to use lukewarm water from the faucet.  When entering a plant in a flower show it is essential that the leaves be clean and under the hairy surface, shiny and green. I have often taken a flowering plant to the kitchen faucet and holding the plant at an angle with the leaves under the slightly warm running water allowed the dust to be washed down the sink.  Only the larger leaves are washed as getting the center of the plant wet can cause the rosette at the center of the plant to stay wet and cold too long and start to cause rot there.

Searching online for materials for this article I was amazed to find many of the common myths about African violets repeated, only a few sources did I consider accurate enough to list here.
Lyndon Lyon, one of the long time growers of African Violets does have a good page on violet culture and I have taken the liberty of copying their instructions here.

WELCOME HOME - One of the first mistakes many people make after bringing new plants home, be it shipped from a greenhouse far away or the local supermarket, is to immediately repot them. THIS IS NOT A GOOD PRACTICE! Plants need a chance to adjust to new surroundings, light, temperatures, humidity, any change in condition before attempting to repot. A good rule of thumb is to wait 4 weeks before repotting. When you are ready, refer to the section on "Potting" for a very important message!

LIGHTING - In our greenhouses, plants are bred, propagated, and grown in both natural light and fluorescent light. We find that plants grown under fluorescent lighting tend to have a more vivid color and larger blooms. Variegated foliage is more intensified, too.
       Adequate light is very important for abundant bloom. Any window that has strong, bright light is good. Mild direct sunshine is beneficial. Shield violets from hot mid- day sun with sheer curtains. Turn pots 1/4 turn every two days to promote even growth, so that your plant does not grow "lopsided". Light intensity decreases sharply as you move away from the light source, so do keep the plants as near the window as possible.
       If you do not have good natural light, use fluorescent lights 12 hours a day. Cool white, daylight or tubes designed specifically for growing plants may be used alone or in combination. Distance from lights depends upon intensity and type of tube as well as variety of plant. A general rule is 12 to 16 inches from top of pot to bottom of light tube for standard growing varieties and 6 to 10 inches for miniature varieties. Light fixtures should be adjustable, to raise or lower to attain desired height.
       If plants grow upright with long leaf stems, move them closer to the lights. If they grow too compactly or become hard and brittle, move them further away from the lights. At proper distance (and with proper feeding), plants will be flat uniform rosettes with many blooms.

WATERING - Improper watering is one of the most common reasons for failure of African violets. Always use room temperature water, watering only when the top of the soil feels slightly dry to the touch. Use water that is fit for drinking. Never use water that has been through a softener. Watering may be from the top or bottom, by wicking, or you may wish to choose one of the many self- watering pots available today. Never allow plants to stand in water after the soil has taken up what it can hold. After 15 to 20 minutes pour off any water that is left in the saucer. Violets do not like wet feet!
       About once a month water should be generously run through the pot from the top to flush out accumulating salts. After this is done, put your plants on several layers of newspaper to absorb the excess water, preferable overnight.

TEMPERATURE & HUMIDITY - The ideal temperature is 65 to 70 degrees at night with a 5 to 10 degree rise during the day. Temperatures below 60 degrees for any extended period will slow the growth. If it is too high, plants will grow sappy and spindly, with too few blooms which drop before gaining good size. Better a bit cool than to hot.
       The humidity is best around 40% to 60%. Humidifiers are great if you have an unusually dry house. Placing your plants on trays of moist pebbles would be a simple solution. Plants may be misted, but not while exposed to direct sun. African violets do like fresh air but do not like drafts!

FEEDING - Many times people ask "Why aren't my violets blooming?" And our first response is "Are you feeding your plants?" Either lack of fertilizer or too infrequent fertilizing is one of the reasons for lack of blossoms, blooms small in size and foliage that is pale or light green. When using soiless mixes, as most growers do today, it is necessary to use a diluted fertilizer solution each time the plant is watered. We recommend using a well-balanced fertilizer such as 15-30-15 at the rate of 1/4 teaspoon per gallon of water each and every time you water. Do not think because a little fertilizer makes them bloom nicely, more will make them even better! Excess fertilizer will burn the roots and may cause hard, brittle, foliage.

POTTING - The majority of growers today use "soiless" potting mixes. These mixes are light and porous, providing good drainage and allowing easy root penetration. Violets and most houseplants do well in these mixes. It should be sterilized to eliminate harmful bacteria that could cause problems later on. If you do not make your own mix, buy one made for African violets. Avoid heavy mixes as these have poor drainage and can become compressed and hard, staying wet and eventually rotting the root system of your plant.
       The type of pot one uses is purely a matter of preference. We prefer plastic pots, short or squatty type, not tall. To determine the correct pot size for your plant remember this rule of thumb: The plants diameter should be 3 times the diameter of the pot before potting up to the next size pot. We recommend you do not skip pot sizes. (Do not jump plants from a 2" pot into a 4" pot.)

GROOMING - Keep your plants clean! Remove dead leaves and faded blossoms. Just like the knick knacks around your home, plants gather dust. Use a soft brush or soft damp sponge to gently remove dust and lint. Every 4 to 6 weeks a gentle washing of the leaves using a weak stream of tepid water will make for a happy plant. Remove excess water by patting dry with tissues. Do not expose to direct sunlight or drafts while foliage is wet. Remove "suckers" (those little plantlets that form where the leaf stem is attached to the trunk) before they get big and misshape the plant; except on trailing violets

 In addition other sources I can recommend are on line and are very helpful They are the links below.
  

Click here: Doctor Optimara

Click here: Optimara Violet Glossary: H
Holtkamp Greenhouses: The largest grower of African Violets in the world. Founded by Hermann Holtkamp. Holtkamp Greenhouses is the originator of Optimara and Rhapsodie varieties. Their research and development efforts are some of the most respected in the industry, creating many new varieties, each year, in both the U.S. and Germany. Holtkamp Greenhouses is credited with a number of notable innovations, including multiflorescence, semper florescence and non-dropping flowers. Many of Holtkamp's most recent innovations have evolved out of their Space Violet program.

 Lakes Area Violet Growers ~ Chimeras, How to Propagate Them