By Melanie Mathieson
The Gardening Guru
Many of the house plants and annuals available here in our gardening zone are ones that grow in the wild or as perennials in a much warmer climate.
One example of this is the African violet—a popular house plant well-suited to growing in pots in homes in Canada which, as the name suggests, is native to the wild in Africa.
The African violet (Saintpaulia species) is popular because it grows and flowers under natural or artificial light conditions found in the average home. As well, many different varieties, types, and flower colours—ranging from white and pink to lavender and vibrant purples—exist.
Drainage is one of the most important considerations in choosing or preparing a soil mixture for African violets. Pre-packaged African violet soil mixes are available, or you can mix your own with equal parts of peat moss, vermiculite, and perlite.
Any pot is suitable as long as they have drainage holes.
African violets should not be watered only as needed because their water needs vary with the soil mixture, drainage, light, temperature, and humidity. Plants in clay pots require more frequent watering than those in plastic ones since evaporation is greater.
In general, water African violets whenever the soil surface feels dry to the touch, but before it becomes hard or the plant wilts.
African violets may be watered from the top or bottom. When watering from the top, apply enough to thoroughly saturate the soil and discard excess water that drains through the bottom of the pot.
Make sure the temperature of the water is the same, or slightly warmer, than that of the room. If cold water touches relatively warm leaves, it will cause yellowish spots or streaks on the upper leaf surfaces.
Self-watering pots are suitable for your African violets, as well.
Violets also can benefit from watering from the bottom by placing the pot in a container to which about one inch of water is added. When the soil surface becomes moist, remove the pot, allow it to drain, and pour out the excess water.
Just remember that the violets occasionally should be watered from the top to flush accumulated fertilizer salts from the soil.
For best growth and flowering, African violets require bright light—the amount of light within three feet of a southeast- or southwest-facing window, but no direct sunlight.
The appearance of a plant will indicate whether light levels are too high, too low, or just right. If light is too low, the leaves usually are thin and deep green, and appear to reach up for light.
The plants may grow, but will flower poorly or not at all.
In such instances, supplemental artificial light will help promote flowering.
Excessive light, meanwhile, causes the leaves to be pale or greenish-yellow. Some may show dark green areas where they have been shaded by upper leaves.
Growth slows when light is too high and plants become very compact. Flowering also will begin to decrease.
Growth and flowering of African violets also is affected by duration of exposure to light and darkness. To bloom, they need at least eight-12 hours of light (and up to 16) and eight hours of darkness per day.
A plant that gets the right level of light, but for too short a period, will do poorly compared to one given weak light for a long period.
Where natural light is unavailable or reduced, African violets can be grown under artificial light. Incandescent light may be used, but fluorescent lamps give better results.
African violets prefer a night temperature of 65-70 degrees Fahrenheit, but will grow satisfactorily at 60-80 degrees F. Under prolonged high temperatures, growth and flowering is reduced.
During hot weather, place plants in the coolest place in the home or in an air-conditioned room.
African violets grow best in high humidity, which can be achieved by setting pots in water-tight metal or plastic trays filled with pebbles and water. Avoid placing pots directly in water to prevent root damage.
Water-soluble fertilizers, such as 20-20-20 or 15-30-15, commonly are sold for use on African violets. Mix the fertilizer in water at one-fourth the recommended rate and apply it each time you water.
The soil should be moist before dissolved fertilizer is applied. Then discard excess water and fertilizer solution that drains from the bottom.
A gradual loss in leaf colour, combined with reduced growth and flowering, usually indicates the plant needs fertilizer.
If in doubt, fertilize one or two plants and wait 10 days to see if you see a reaction. If plant growth is evident and the leaves become darker in colour, fertilize the rest of the plants, too.
When over-fertilized, African violets develop tight centres and the new leaves take on a rusty appearance.
African violets easily are propagated by leaf cuttings by selecting a healthy and firm leaf from the middle of the plant, then snapping or cutting it off at the stem but leaving the petiole (leaf stem) intact.
The petiole should be trimmed to about one to one-and-a-half inches in length. Insert the petiole into a hole made with a pencil or similar tool, into a combination of half-vermiculite/half-sand or half-vermiculite/half-potting mix.
Roots normally form at the petiole base in three-four weeks, and leaves of new plants appear three-four weeks after roots form. Plants will begin flowering six-nine months later.
Multiple crowns can be carefully divided and each planted into new pots. Older, “leggy” plants can be successfully re-rooted by cutting the plant off at the soil level and then repotted so the leafless stem is positioned below the soil line, where it can grow new roots.
Although I’ve never had any problems with African violets, various diseases can affect them. Adequate spacing in the pot, use of sterilized soil, and prompt removal of faded flowers and unhealthy leaves really will help prevent disease problems.
Here are a few tips if you encounter any of the following:
•Mealy bugs and cottony egg masses can be controlled by mixing alcohol with an equal amount of water, and touching each insect or egg mass with a cotton swab dipped in the solution.
•Any other insects and mites can be managed with insecticidal soap sprays.
•Cyclamen mites cause severe stunting of plants and are very difficult to control. Unfortunately, the best management strategy for this pest is to discard affected plants.
•Root diseases usually are caused by over-watering. The first sign of this problem usually is a limp, unthrifty plant.
In most cases, the plant should be discarded.
•Petiole (leaf stem) rot occurs when petioles touch the edge of the pot and develop brown, sunken areas at points of contact.
This injury is caused by fertilizer salts that accumulate on the rims of clay pots.
Petiole rot can be avoided by waxing the pot rim and covering it with aluminum foil, or repotting to a larger pot.
Now that you’re aware that an African violet could be a perfect house plant for you, look for them in local nurseries and flower shops at this time of year.