African violet

Identification and origin

Streptocarpus ionanthus belongs to the gesneriad family, Gesneriaceae, like gloxinia. Now placed in the genus Streptocarpus, it is still sold under its former name, Saintpaulia ionantha. It is native to East Africa, in Tanzania and Kenya. It is not related to true violets in the genus Viola: ionanthus means “with violet-like flowers.”

The plant forms a low rosette 6–9 in tall and wide. Its thick, rounded to oval leaves with slightly scalloped edges are covered in fine hairs that give them a velvety feel; medium to dark green above, they are often red, pink, or purple underneath and sit on long leafstalks. The flowers, up to 1 in across, come in groups of three to ten on a stalk that rises above the foliage. Each has two lips and yellow anthers. A flower cluster lasts three to six weeks, and a well-grown plant reblooms several times a year.

Thousands of cultivars have been bred since the first hybrids were developed in Los Angeles in the 1920s. They are grouped by size (from micro-miniature to large), by habit (rosette or trailing), and by flower form: single, semi-double, double, fringed, star-shaped, or “wasp.” Leaves can be ruffled, scalloped, or edged in cream. ‘Nightfall’, ‘Persian Prince’, and ‘Little Ruby’ are a few examples.

Light

Good light drives flowering. Place the plant within 3 ft of a large, bright window, but out of direct afternoon sun; a north- or east-facing window often suits it very well. Watch the leaves: thin, dark green leaves on long stalks mean too little light; pale, yellowish, small leaves mean too much.

African violets also grow very well under artificial light, with fluorescent tubes or LED lamps placed 4–8 in above the foliage and left on twelve to sixteen hours a day. They need at least eight hours of darkness daily to bloom.

Watering

Do not water on a fixed schedule: needs vary with the potting mix, light, and temperature. Water when the surface of the mix feels dry to the touch, but before it hardens or the plant wilts. Clay pots dry out faster than plastic ones.

Always use room-temperature or slightly warmer water: cold water touching the leaves leaves white to yellow spots or rings. Avoid softened water. There are two ways to water:

• From the top: pour water onto the mix without wetting the leaves until it drains out, then empty the saucer.
• From below: set the pot in 1 in of water; as soon as the surface of the mix is moist, lift it out and let it drain. Water from the top now and then to flush out accumulated fertilizer salts.

Never let the plant sit in water: overwatering is one of the most common reasons African violets die. Relative humidity of 40 to 60 percent suits it; group plants together or set them on a tray of wet pebbles.

Potting mix

The fine roots need a light, porous, very well-drained mix: for example, equal parts peat moss or coir, vermiculite, and perlite, or a commercial African violet mix lightened with perlite. The ideal pH is 6.0 to 6.5. The pot must have drainage holes; avoid decorative pots without them.

Fertilize at every watering with a water-soluble fertilizer mixed at one-quarter strength, applied to already moist mix. Lower leaves turning yellow and slower growth point to a lack of fertilizer; a tight center and rusty-looking new leaves point to too much.

Temperature

African violets like 64–81 °F, ideally around 70 °F, with nights of 64–70 °F. Nights below 61 °F stunt growth, and recovery can take a long time; below 50 °F, leaves darken, wither, and look water-soaked. Above 84 °F, growth and flowering slow down: in hot weather, move the plant to the coolest room. Steady temperatures suit it best. Outdoors it can only be grown in USDA zones 11a to 12b.

Repotting

Set the plant with its crown above the surface and press the mix gently around it. Over time, the lower leaves die and a bare stem, the “neck,” lifts the rosette. When that happens, repot the plant deeper, burying the stem up to the lowest leaves: it will grow new roots there.

Wash reused pots with soapy water or diluted bleach. On clay pots, fertilizer salts that build up on the rim damage the leafstalks resting on it; protect the rim with wax or aluminum foil.

Pruning

No pruning is needed. Remove spent flowers and dead or yellowed leaves with tweezers or small pointed pruners; keeping the plant clean helps prevent disease.

Propagation

Leaf cuttings are easy. Choose a firm, healthy leaf from the middle of the rosette and cut it with a clean knife, leaving 1–2 in of leafstalk. Insert the stalk at a slant into a moist mix of equal parts vermiculite and sand, or vermiculite and potting mix. Water, let it drain, cover the pot with a clear plastic bag, and place it in a bright spot. Roots form in three to four weeks, and the first leaves of new plants appear six to eight weeks after sticking the cutting. Several plantlets form at the base of the stalk: separate them and pot them individually. They bloom six to nine months later.

Plants with several crowns can also be divided: make sure each piece keeps some roots.

Common problems

• No flowers: too little light, temperatures too low, or too little or too much fertilizer.
• Crown and lower leaves water-soaked, then shriveled: crown rot from overwatering; it is often fatal.
• Limp plant with brown, slimy roots: root rot, rarely recoverable.
• Pale spots or rings on leaves: cold water on the foliage.
• White or gray powder on leaves: powdery mildew; remove affected leaves and space plants out.
• Tight, crinkled center and stunted plant: cyclamen mites, very hard to control; discarding the plant is the best option.
• White cottony masses: mealybugs; dab them with a cotton swab dipped in rubbing alcohol mixed half and half with water.

Isolate affected plants, since pests spread easily from one violet to another. The same symptom can have several causes: always check light, temperature, watering, and roots.

Toxicity

No toxicity has been reported: the African violet is listed as non-toxic to dogs, cats, and horses.