African violet spots on leaves: causes and what to do
8 results in the diagnosis tree begin with spots on the leaves, 5 of them marked likely when the answers fit. They are ordered here for African violet (Streptocarpus ionanthus), using what its sources say about light, soil moisture, humidity and pests and diseases and 2 problems recorded for it.
Sources last read 14 September 2026.
Streptocarpus ionanthus is a species of Streptocarpus in the section Saintpaulia, commonly known as an African violet. It is native to eastern and southwestern Tanzania. Wikipedia, CC BY-SA 4.0
Native range: E. & SW. Tanzania (seasonally dry tropical). Also sold as Kenya Violet and Usambara violet.
What African violet’s sources say that bears on this
- Light
- Medium lightClemson Extension · read 13 September 2026Partial shadeRHS · read 13 September 2026
- Soil moisture
- Moist but well-drainedRHS · read 13 September 2026
- Humidity
- ASHRAE recommends indoor relative humidity between 30% and 60%Penn State Extension · read 13 September 2026
- Pests and diseases
- Can be troubled by mealybugs.NC State Extension · read 13 September 2026Can be troubled by tarsonemid mite, vine weevil, thrips, mealybugs and greenhouse leafhoppers. Diseases: powdery mildews or grey moulds (botrytis).RHS · read 13 September 2026
How this shows up on an African violet
Fuzzy gray growth over spreading patches on leaves and stems
Patches of the African violet turn soft and collapse under a gray, velvety coating.
RHS lists gray mold among the diseases it may get. It thrives on spent flowers and fallen leaves left on the plant, and moves from there to living tissue.
Telling it apart: The texture. Tissue under gray mold is soft and rotting; sun scorch is dry.
RHS · read 13 September 2026Pale powdery spots that merge into a white film
A thin white film spreads over the leaves of the African violet. It rubs off, but returns.
RHS lists powdery mildew among the diseases it may get. It favors crowded plants, poor air movement and roots kept too dry.
Telling it apart: Where the white is. Mildew coats the tops of leaves; mealybugs hide in joints and under leaves.
RHS · read 13 September 2026Possible causes, likeliest first for an African violet
Most likely powdery mildew
Ranked higher because African violet's recorded problems point this way.
- Pale powdery spots that merge into a white film RHS
Why: A white coating that wipes off is the surface growth of a fungus.
What to try:
- Remove the worst-affected leaves.
- Improve air movement around the african violet and space it away from others.
What would settle it: Wipe a patch. Powdery mildew comes away and leaves a yellowed patch beneath. White that does not wipe off is part of the leaf, or a mineral deposit from hard water.
Most likely cold
Ranked higher for African violet because of what its sources say.
Its RHS hardiness rating puts this plant's cold floor at 15°C or above, so a cold windowsill at night is a strong explanation.
- H1A — warmer than 15°C RHS · read 13 September 2026
Why: Soft, dark patches rather than crisp ones are damaged tissue rather than dried tissue.
What to try:
- Move it away from the glass at night, or keep the curtain on the room side of the african violet.
- Leave damaged leaves until new growth appears, then remove the worst of them.
What would settle it: Where the african violet sits at night, and what the glass feels like at that hour. Damage that appeared after one cold night, on the side facing the window, is the pattern.
Most likely spider mites
Why: Spider mites feed on individual leaf cells, and each emptied cell shows as a pale speck.
What to try:
- Move the african violet away from other plants.
- Wash the leaves, top and underside, with a strong spray of water in a shower or sink.
What would settle it: Hold a sheet of white paper under a leaf and tap the leaf. Tiny specks that move across the paper are mites.
Less likely for an African violet, still possible
Questions
- What usually causes spots on the leaves on an African violet?
- For African violet: powdery mildew, cold and spider mites.
- How can I tell which one it is on my African violet?
- What do the marks look like? Pale, dry, bleached patches on the side facing the window; Brown or black spots, many with a yellow ring around them; Tiny pale speckles all over, sometimes with fine webbing underneath; A white powdery coating that wipes off; Silvery streaks with tiny black dots; Dark, soft, water-soaked patches.
- What do African violet's sources say about its light?
- Clemson Extension: Medium light. RHS: Partial shade.
- What does this look like on an African violet?
- Patches of the African violet turn soft and collapse under a gray, velvety coating. Telling it apart: The texture. Tissue under gray mold is soft and rotting; sun scorch is dry.
Other plants that show spots on the leaves
Barberton daisyDark spots with a yellow halo spreading across the leaves
Bearded irisFuzzy gray growth over spreading patches on leaves and stems
Bigleaf hydrangeaBrown or black spots on the leaves that grow and merge
Blue passion flowerBleached patches on the side facing the glass
Busy LizzieAngular pale patches and a downy coating on the undersides
Calla lilySilvery patches dotted with tiny black spots: thrips
Something else wrong with the African violet?
What this does not cover
This page orders a decision tree's results using a plant's sourced care. It has not seen your plant, its pot or its window, and two problems at once are common: that is the usual reason a confident answer turns out wrong. The questions in the diagnosis tool narrow it further than a list can.