Ask a Master Gardener: How to keep your African violet healthy

Did you know the National Garden Bureau has named African violet as its houseplant of the year for 2024? Their choice is an excellent one. Few plants give more enjoyment while asking for little in return than African violet.

They thrive in most interior settings, provide nearly continuous color, and are inexpensive to purchase. As we await the upcoming growing season, winter is an ideal time of the year to start (or add to) an African violet collection.

As its name implies, African violet is native to Africa. Today's African violets come in what appears to be a limitless array of colors, shapes, sizes, and forms. Enthusiastic breeders all over the world have brought out the best the Gesneriad Saintpaulia ionantha has to offer. Its ease of mutation, whimsical flower shapes and colors, and leaf variations make it especially fun to collect.

Early hybridization of this plant involved crossing similar Saintpaulia species in the quest to obtain more robust plants. The result was violets with improved horticultural attributes but only with blue flowers. The reds (wines), whites and pinks that we enjoy today are the result of American hybridizers working in the 1930s and 1940s. The harder to achieve coral pink and coral red were added later. Yellow is the latest flower color to be developed.

In addition to breeding for different flower colors, hybridizers also have developed multi-colored blossoms, with petals that are striped, spotted or having edges of contrasting color (picotee appearance). Other characteristics improved include petal count, blossom count and blossom shape.

Since African violet is native to warm areas, their location in the home must be kept warm. Maintain night temperatures between 65 and 70 degrees, day temperatures should be 10 degrees warmer. Do not expose plants to temperatures below 60 degrees or above 80 degrees.

Soil-less growing media produce plants with good growth and flowering, although some violet fanciers prefer using soil rich in humus. If soil is used it should be sterilized to reduce the risk of disease infestation. Soil-less mixes are considered to be biologically inert and do not need to be sterilized.

Proper watering is key for success with African violets. Keep plants uniformly moist, but not wet, since they are easily killed by excess moisture. Wick watering using a candle wick or nylon twine extending from the growing medium via a hole in the bottom of the pot to a water/nutrient reservoir below the pot works well. Plastic tubs used to hold margarine can be used for the latter. Leaf spotting can be a problem when water 10 degrees above or below the leaf temperature contacts the leaves. Therefore, if overhead watering is practiced, use water that is room temperature and try to keep it off the leaves.

Also, relative humidity is important, and most homes have low humidity, especially during winter months. To increase the relative humidity around plants, place them on shallow trays of gravel containing water. However, make sure the pots do not sit in water. Home humidifiers also work well as a method of increasing relative humidity.

If located properly and watered regularly, African violets need little other care besides occasional fertilization. Use either special African violet fertilizers or a houseplant fertilizer high in phosphorus. A very diluted fertilizer solution at each watering keeps growth constant and eliminates any chances of over fertilization. Pale green leaf color may indicate too much sunlight or low fertility. Do not use water softened by a system using salt in the process.

Mealybug is the most troublesome pest of African violets. New plants should be quarantined several weeks before introducing them to your collection. If mealybugs appear, swabbing them with isopropyl (rubbing) alcohol using a cotton swab can be an effective means of control unless populations are excessive.

African violets seldom need pots larger than 4 inches in diameter. The danger of over-watering and development of root and crown rots increases if pots are too big. Old plants sometimes develop long woody stems. The tips of these plants may be cut off and rooted to form new, more compact plants. However, plants developed from leaf cuttings are generally more vigorous and bloom more abundantly.

(Source: Missouri Environment & Garden Articles, Dr. David Trinklein)

Dhruba Dhakal, PhD is a University of Missouri Extension Horticulturist, serving to Missourians for about a decade in Central Missouri. Dhakal can be contacted at [email protected] with gardening questions.