African violet ( Saintpaulia )

Saintpaulias, commonly known as African violets are widely grown, attractive houseplants originating from tropical East Africa. They are available in a many colours from white, through pink and red to purple and various flower types. With careful cultivation they can flower for many months and the compact plants are ideal for small spaces such as windowsills.

African violet

Quick facts

Common name African violet
Botanical name Saintpaulia
Group Houseplant
Flowering time All year
Planting time Any season
Height and spread 5-7.5cm (2-4in) by 7-20cm (3-8in)
Aspect Bright filtered or indirect light
Hardiness Frost tender
Difficulty Moderate

Cultivation notes

From spring to autumn, position plants in a brightly lit situation out of direct sunlight, such as on an east or west-facing windowsill. In the winter due to low light levels a south-facing windowsill is suitable. 

The minimum temperature required is 18-24°C (65-75°F) by day and 16°C (60°F) by night. Avoid cold draughts and sudden changes in temperature.

It is essential to provide humidity around the plant by standing the pot on a saucer filled with gravel, expanded clay granules (Hydroleca) or recycled lightweight aggregate (Hortag). Keep the water level just below the surface of the gravel or aggregate. 

Watering

Keep compost moist but wait until the surface of the compost is dry before watering. Bear in mind the moisture-retaining qualities of the compost and avoid watering too frequently.

Use water at room temperature. Do not let the water come in contact with the leaves, especially cold water direct from the tap, as it will chill plants and can mark the leaves.

Feeding

Supplementary feeding can be carried out using a dilute liquid feed at three to four week intervals during spring and summer when plants are actively growing. 

Compost

Root growth is fibrous and a good percentage of organic matter is required, therefore pot into John Innes No.2 compost, with 30 percent by volume added peat substitute. Alternatively use specialist houseplant compost.

Repotting of established plants is usually necessary only after two to three years and should be carried out in spring. Use 9-10cm (3½-4in) pots for final potting, but for growing very large plants and for the most aesthetically pleasing effect, shallow 12cm (5in) pots or pans may be used. 

Propagation

Leaf cuttings

Saintpaulia are easy to propagate from leaf cuttings.

  1. Choose leaves that are almost full size and remove from the plant with the stalk attached.
  2. Fill pots with free draining compost such as seed and cutting compost or mix equal quantities of multipurpose compost and sharp sand or perlite. Insert the leaf so the base of the leaf blade just touches the compost.
  3. Water and allow to drain. Place in a propagator or a clear plastic bag in a light place out of direct sunlight. Cuttings can be taken in February if a soil temperature of 18°C (65°F) can be maintained; otherwise it is best to wait until April.
  4. New plants should form in four to five weeks at the base of the leaf. At this time remove covers and allow them to grow on until large enough to pot up individually.

Division

Sever side crowns from the main plant and treat as for leaf cuttings to encourage rooting. Suckers can also be separated from the parent plant with roots attached and potted up.

Seed

  1. Sow seed thinly in spring on sowing compost, the top 2.5cm (1in) of  which is finely sieved. Do not cover seeds with compost. Cover the tray with polythene, cling film or a sheet of glass.
  2. Put in a light but shaded place, at a temperature of 18-24°C (65-75°F); germination usually takes 3-4 weeks.
  3. Do not allow the seedlings to dry out. If a propagator is unavailable a moist atmosphere can be maintained by covering with a plastic bag which is ventilated regularly.
  4. Provide seedlings with good light but avoid direct sunlight.
  5. Pot into individual posts when large enough to handle.

Seed saved from named cultivars may germinate satisfactorily, but it is unlikely plants will come true to type and they may be considerably inferior to the parent plants.

Cultivar Selection

There are many variations in flower colour and form available. Garden centres generally stock a selection and specialist nurseries such as Dibleys will supply a wider range of named cultivars.

Links

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Problems

Leaf problems

African violets suffer leaf problems common to many houseplants.

  • Brownish or straw coloured blotches: can be the result of strong direct sunlight
  • Small whitish papery spots, sometimes elongated or in a line across a leaf: due to cells killed by the sun’s rays concentrated through irregularities in window glass, or through water droplets
  • Scorching and bleaching, with stunted growth: too high a light intensity
  • Elongated leaf stalks: too low a light intensity
  • Blotches, rings or pale or white spots: using water that is too cold. It should be at room temperature. Avoid wetting the foliage when watering
  • Leaves pale green, edges turn up: temperature too low
  • Leaves limp and wilted: under-watering or over-watering

Nutrient deficiencies

  • Leaf growth strong but yellow patches along leaf edges: potash deficiency
  • Some leaf dieback, leaves small and dark, grey green leaves arranged in flattened rosette: phosphate deficiency
  • Leaves small hard yellowish particularly near centre of the plant, few flowers: nitrogen deficiency

Non-flowering

Lack of flowers is often caused by too little light. At least 12 hours of light per day are needed for good flowers, but lack of humidity, cold air and over-potting can also result in lack of flowers.

Pests and diseases

When it comes to pests African violets can suffer from aphids, glasshouse leafhopper, mealybug including root mealybug, tarsonemid mites, thrips and vine weevil.

Diseases such as botrytis and powdery mildew are also an occasional problem.

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