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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Growing African Violets

This article was published originally on 12/15/2000

African violets are one of America's most popular houseplants. Under the right growing conditions, they are able to bloom almost continuously indoors. They are also available in a wide range of flower colors, leaf types, and growth habits (trailing, miniature, standard, etc.).

History

The history of African Violets dates back to the late 18th century. Baron Walter von St. Paul discovered these blooming beauties growing in West Africa and sent samples or seed home to Germany. By the early 1900's African violets were blooming in Europe and around the world. The development of hybrid varieties with violet, purple, and blue flower colors in the late 1920's by the Los Angeles nursery of Armacost and Roysten increased the popularity of African violets. Since the 1920's hundreds of cultivars have been developed with an immense variety of flower and leaf colors, shapes, and sizes.

Colors, Types, and Habits

Today, flower colors include blue, purple, red-violet, orchid, lavender, red pink, white, and bi-color or multi-colored. There are single, double, semi-double, star-shaped, fringed, and ruffled flower types. Leaf types include plain, ruffled, fringed, scalloped, spooned, pointed, and variegated. The American Violet Society has 4 classes of African violets based on plant size: miniature (less than 6 inches in diameter), semi-miniature (6 to 8 inches), standard (8 to 16 inches), and large (over 16 inches).

No matter which flower color, leaf type, or habit you select, the care for all types of African violets is similar. While these are relatively easy to grow houseplants, they do require consistent care.

Light

Proper light is essential for good bloom. African violets require more light than most growers first realize. Thin, dark, blue-green leaves with long petioles indicate insufficient light levels. While moderate light is needed, direct light for long periods can be damaging as well. Too much light produces leaves that are small, crinkled, leathery, and yellow with short petioles on stunted plants. Generally, north and eastern exposures are best for African violets. However, if these exposures are not possible, African violets perform beautifully under artificial lights as well. Fluorescent lights suspended approximately 8 inches above the plants for 12 to 16 hours per day will produce sufficient light to initiate blooms in African violets.

Temperature

African violets require temperatures between 65 and 80F. Typically, temperatures below 50 F will cause leaves to darken, become water-soaked, and wither. Temperatures above 85F will slow growth and flowering of African violets and may injure the leaves as well. Water temperature becomes important during the winter months, as cold water directly on the leaves will damage them quickly.

Watering

Watering African violets is often the most difficult part of their care. They require a moist, well-drained soil. If the soils are too wet, the plants may rot. If plants are too dry, they will not grow or flower well. Many people sub-irrigate African violets. This means placing the plant in a saucer of water and allowing the plant to soak up water from the bottom of the pot. This prevents injury from cold water on the leaves and insures the entire soil profile is moist. However, care must be taken not to allow the plants to sit for long periods in water as they may rot quickly. Allow the top inch of the soil to dry before sub-irrigating again. African violets can also be watered from the top if room temperature water is used and the foliage remains dry. In fact, it is recommended to irrigate from the top occasionally to prevent salt accumulation. Wick watering is another method that is increasing in popularity. This is a continuous watering system with a water reservoir at the base of the plant and an absorbent wick that connects the soil and the water reservoir. This method is effective in maintaining an even moisture level of the soil. However, periodic leaching of the soil profile with water from the top might be necessary to prevent the accumulation of salts.

Fertilization

Regular fertilization is needed to encourage plants to bloom throughout the year. A complete fertilizer at a low rate is recommended. Excessive fertilization leads to vigorous vegetative growth, poor flowering, and the accumulation of salts in the soil. The accumulation of salts can ultimately damage or destroy foliage. Flush soils occasionally with clear water to eliminate salt buildup in the soil.

Soils

A loose, porous, fertile soil or soilless mix that is slightly acidic (6.0 or 6.5) is needed for growing African violets. Peat-based soils that have been pasteurized are best. Garden or field soil is not satisfactory alone since it is often poorly drained and compacts easily. Many commercial soiless mixes are available. Refer to soils for houseplants (PM 713f) for more recipes for mixing your own soils.

African violets make great houseplants. With a proper environment and regular care they will reward you with blooms all year.

Insects and Disease

If grown properly, African violets have few problems with insects or diseases. Some of the more common pest problems include mites and mealybugs. Mites are small spiders that attack the undersides of the leaves, new growth, and flowers. Small webs are normally found around the leaf axils (junction of leaf petiole and main stem). Mites are so small they are not visible to the naked eye and the damage to the plant is often noticed first. Control of mites may require isolating the infected plant and spraying with soapy water or a miticide.

Mealybugs are easier to identify, as they are larger than spider mites. Mealybugs are whitish and often exude a "cottony mass" of sticky material for protection. Control requires soapy water baths or removal of the bugs with alcohol dipped cotton swabs.

Whenever, the foliage of African violets are wetted, warm water must be used and sufficient time allowed for the leaves to dry out before dark. Foliage that stays moist is prone to fungal diseases. One common fungal foliar disease is powdery mildew. Infected leaves will have small circles of a gray or whitish powder on the topside of the leaves. Control for powdery mildew requires the removal of infected leaves and spacing plants out more for better air circulation between plants. Powdery mildew tends to more of a problem on plants that are overcrowded.

Crown rot is another common fungal problem of African violets that are overwatered. Crown rot causes the main stem and lower leaves to appear water-soaked, shrivel and die. Crown rot usually leads to death of the plant. Allowing the top of the soil to dry out between watering will prevent crown rot.



This article originally appeared in the December 15, 2000 issue, pp. 123-124.

Year of Publication: 
2000
Issue: 
IC-483(25) -- December 15, 2000