African violets (Saintpaulia) are popular houseplants in Ontario, in part because they can flower continuously under ideal conditions. They are members of the Gesneriaceae family, and are not related to the hardy outdoor violets that belong to the Violaceae family.
How to grow African violets
Light: African violets are sensitive to quality and quantity of light. They do not need direct sunlight, and grow well near east- or north- facing windows. In the winter, sunny, warmer windows are best. The plants prefer 10-12 hours of bright, indirect light and around 8 hours of darkness. Too little light will result in long leggy stems and no bloom. With too much light, the plants will be stunted, with small, crinkly, leathery yellow leaves.
African violets do well under grow lights, but not too close to the source. For example, if fluorescent lights are used, these should be suspended 10-20 cm (4-8 inches) above the plants [to avoid leaf scorching], for 12 to 16 hours a day.
Temperature and Humidity: African violets grow well in the warm, dry air present in homes. A temperature range of 18-27°C (64-80°F) is ideal. Do not keep at temperatures below 15°C (60°F) at night or the plant growth will become stunted. Avoid extreme changes in temperature or drafts.
Water: The soil should be kept moist, but not soggy or the roots may rot. Keep leaves dry to avoid unsightly spots or rings. Plants that are too dry will not grow or flower well.
Using tepid water, water when the soil surface is dry to the touch, but before it becomes hard or the plant starts to wilt. To water from the top, saturate the soil and discard water that drains through the pot. Occasional top watering is recommended to prevent buildup of salt deposits in the soil. To water from the bottom, place the pot in a tray filled with about 2.5 cm (1 inch) of water, for an hour or so, just until the soil surface becomes moist. Then allow the water to drain and discard excess water. Repeat when the top 2.5 cm (1 inch) of soil is dry.
Soil: Plants do best in a loose, porous soil or soilless mix. It is critical that the soil used drains well. Equal parts of peat moss, vermiculite and perlite are recommended. Packaged African violet soil mixes are also available. Soil mixture pH should be in the range of 6.4-6.9. Plant roots are tender and will have difficulty growing if soil is too heavy.
Planting tips: When planting, ensure the crown remains just above the surface of the soil, with the soil pressed firmly around it.
Use pots that are as small as possible, since in order to produce bloom, roots should be pot-bound. When repotting into a larger pot, select one that is barely bigger than the current one.
Fertilize: Use a water soluble balanced fertilizer (e.g., 20-20-20) or (to encourage more rapid flowering) a 15-30-15 fertilizer. Dilute the fertilizer to one-quarter the recommended strength and apply it once a week or each time the plant is watered. The soil should be moist before fertilizer is applied. Watch for signs of over-fertilizing, like poor flowering, leaf tip-burn, the formation of rusty new leaves, or leaves that wilt or turn brown.
Prune: Keep the plant healthy by breaking off the lower, older leaves (usually a few a month). Once flowers start to fade, pick them off gently, to encourage more flowers to develop.
Pests and diseases: Insects are not usually a problem. Insecticidal soap sprays may be used for most insects or mites, but may damage leaves or flowers. Dab mealy bugs with alcohol.
Thrips or cyclamen mites are difficult to get rid of, often it is best to discard the plant. Spray white flies with a strong stream of tepid tap water and dry the leaves … or get rid of the plant.
Root diseases usually occur because of over-watering. African violets are susceptible to fungal diseases. To protect against these fungal diseases, lower the humidity and increase air circulation around the plant. With Botrytis blight or powdery mildew pick off and destroy the diseased plant parts. To avoid crown rot, a fungus that occurs with overwatering or in recently repotted plants, allow the top of the soil to dry completely between waterings.
Propagation: Propagate by leaf cuttings or suckers removed from the mother plant. In both cases, the plants should be watered the day before. Pot into 5 cm (2 inch) pots.
For leaf cuttings, snap the leaf off at the stem, leaving the leaf stem (petiole) intact. Insert the leaf into pot that contains a mix of (moistened) half vermiculite/half sand, or half vermiculite/half potting mix. Roots should form at the petiole base after 3-4 weeks, and leaves of new plants generally emerge 3-4 weeks after that. The new plant should flower 6-9 months later.
Suckers look like miniature plants, and grow from the sides of the mother plant’s main stem, not the centre (crown) of the plant. Remove the mother plant from its pot, and locate the suckers by gently pushing the leaves apart. Using scissors or a sharp knife, cut the sucker and repot in a small pot filled with potting mix. After around 4-6 months, it should grow into a new plant.
Plants with more than one crown can also be propagated by division. Remove the plant from the pot and identify individual crowns from each plant; pull these apart gently, ensuring that each crown has some roots. Likely some stems will break during this process, but several plants should survive. Simply replant them in small pots. Although African violets can be grown from seed, seeds are hard to find and difficult to germinate.
References
African Violet Society of Canada https://avsc.ca
Iowa State University Extension. African violets. http://www.extension.iastate.edu/publications/rg322.pdf
Missouri Botanical Garden. African violets. https://www.missouribotanicalgarden.org/Portals/0/Gardening/Gardening%20Help/Factsheets/African%20Violets2.pdf
Date prepared: January 2022
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