Polka dot begonia brown leaf tips and edges: causes and what to do
6 results in the diagnosis tree begin with brown tips and edges, 3 of them marked likely when the answers fit. They are ordered here for Polka dot begonia (Begonia maculata), using what its sources say about humidity, soil moisture, cold tolerance, watering and feeding and one problem recorded for it.
Sources last read 14 September 2026.
Begonia maculata, the polka dot begonia, is a species of begonia native to southeast Brazil. It grows naturally in the understory of the Atlantic rainforest, with occurrences confirmed in the Brazilian states of Espírito Santo and Rio de Janeiro. Wikipedia, CC BY-SA 4.0
Native range: Brazil (Rio de Janeiro) (wet tropical). Also sold as trout begonia.
What Polka dot begonia’s sources say that bears on this
- Humidity
- ASHRAE recommends indoor relative humidity between 30% and 60%Penn State Extension · read 13 September 2026
- Soil moisture
- Moist but well-drained or Well-drainedRHS · read 13 September 2026
- Cold tolerance
- H1B — 10–15°CRHS · read 13 September 2026
- Watering
- Does not cope with constant direct sun or with waterlogging. During growth, water moderately and give a balanced liquid fertiliser at every other watering.RHS · read 13 September 2026
- Feeding
- While growing, water moderately, adding a balanced liquid fertiliser at every other watering.RHS · read 13 September 2026
How this shows up on a Polka dot begonia
Brown brittle margins with a green centre
On a polka dot begonia the browning starts furthest from the midrib and works inward, and it crumbles rather than smears. The centre of each leaf blade is untouched.
Transpiration rises as the air dries, and the tissue furthest from a vein loses first. Penn State Extension notes there is no single humidity figure that suits every indoor plant, which is why this site publishes a range rather than a number.
Telling it apart: Whether the damage advances. Dry air marks a leaf and stops; rot keeps going.
Penn State Extension · read 13 September 2026Possible causes, likeliest first for a Polka dot begonia
Most likely cold
Ranked higher for Polka dot begonia because of what its sources say.
Its RHS hardiness rating puts this plant's cold floor at 10°C or above, so a cold windowsill at night is a strong explanation.
- H1B — 10–15°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 polka dot begonia.
- Leave damaged leaves until new growth appears, then remove the worst of them.
What would settle it: Where the polka dot begonia 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 a build-up of salts in the soil
- Clay, Loam, Sand; pH Acid or Neutral RHS · read 13 September 2026
Why: Minerals from tap water and fertiliser are left behind as water evaporates, and a white crust on the compost or the pot rim is where they show.
What to try:
- Water slowly and heavily until several times the pot's volume has run through the drainage hole, to wash the salts out.Useful: pot with drainage holes
- Scrape off the top layer of crusted compost and replace it.
What would settle it: Scrape the crust. If it is gritty and dissolves in water it is mineral; if it is fluffy it is mould, which is a different problem.
Most likely too little water
- Moist but well-drained or Well-drained RHS · read 13 September 2026
Why: Soil dry two inches down leaves the roots nothing to send up, and the leaf edges are the last tissue in line.
What to try:
- Water thoroughly, until it runs from the drainage hole.Useful: pot with drainage holes
- Check the soil with a finger every few days rather than watering on a fixed day.Useful: moisture meter
What would settle it: Water it thoroughly and watch the next new leaves. If they come in with clean edges under steadier watering, the edges were thirst.
Less likely for a Polka dot begonia, still possible
Questions
- What usually causes brown tips and edges on a Polka dot begonia?
- For Polka dot begonia: most likely cold, most likely a build-up of salts in the soil and most likely too little water. Its RHS hardiness rating puts this plant's cold floor at 10°C or above, so a cold windowsill at night is a strong explanation.
- How can I tell which one it is on my Polka dot begonia?
- Is the browning crisp and dry, or soft and dark? Crisp and dry; Soft and dark.
- What do Polka dot begonia's sources say about its soil moisture?
- RHS: Moist but well-drained or Well-drained.
- What does this look like on a Polka dot begonia?
- On a polka dot begonia the browning starts furthest from the midrib and works inward, and it crumbles rather than smears. The centre of each leaf blade is untouched. Telling it apart: Whether the damage advances. Dry air marks a leaf and stops; rot keeps going.
- Is Polka dot begonia safe to handle while I check it?
- Its sources list it as toxic to cats and dogs. Wash your hands after handling the roots or sap, and keep trimmings away from pets.
Other plants that show brown tips and edges
Rex begoniaBrown brittle margins with a green centre
AlocasiaBrown brittle margins with a green centre
Arrowhead plantEdges of the leaf blades brown while the middle stays sound
Asparagus fernBrown brittle margins with a green centre
Baby's tearsBrown tips on the newest leaves first
Bird's nest fernCrisp margins that appear in winter
Something else wrong with the Polka dot begonia?
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.