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Iron Cross Begonia

Begonia masoniana, Begoniaceae

Sources last read 14 September 2026.

Not yet rated How forgiving it is has not been judged here yet.

Iron Cross Begonia (Begonia masoniana), the whole plant.
Kor!An (Корзун Андрей), CC BY-SA 3.0 · Wikimedia Commons

Iron Cross Begonia is toxic

  • Toxic to cats. Toxic principle: Soluble calcium oxalates. Clinical signs: Kidney failure (in grazing animals), vomiting, salivation in dogs/cats. Most toxic part is underground. ASPCA
  • Toxic to dogs. Toxic principle: Soluble calcium oxalates. Clinical signs: Kidney failure (in grazing animals), vomiting, salivation in dogs/cats. Most toxic part is underground. ASPCA
  • Toxic to people. The bulbs are ornamental and should not be eaten. Use gloves and protective gear when handling it. RHS

What the sources say about its care

Light
Partial shade
RHS · read 13 September 2026
Water
Well-drained
RHS · read 13 September 2026
Humidity

No source read publishes a humidity figure for any plant on this site. What follows is general guidance for foliage plants.

ASHRAE recommends indoor relative humidity between 30% and 60% 30–60%
Penn State Extension · read 13 September 2026
Temperature

How cold this tolerates, not what it prefers. No source read for this site publishes a preferred range for a plant indoors.

H1B — 10–15°C 10–15 °C
RHS · read 13 September 2026
Soil
Chalk, Loam, Sand; pH Acid or Alkaline or Neutral
RHS · read 13 September 2026
Toxic to cats
Toxic
ASPCA · read 13 September 2026
Toxic to dogs
Toxic
ASPCA · read 13 September 2026
Harmful to people
The bulbs are ornamental and should not be eaten. Use gloves and protective gear when handling it.
RHS · read 13 September 2026

Routine care

Watering
As active growth slows, water slightly less, letting the soil surface become nearly dry before watering. The plant likes high humidity, which a tray of gravel and water under the pot can raise, but avoid overwatering it.
NC State Extension · read 13 September 2026
Propagation
Iron cross begonia is propagated from leaf or stem cuttings.
NC State Extension · read 13 September 2026
Increase from seed, leaf cuttings or rhizome sections.
RHS · read 13 September 2026
Pruning
Pruning is not needed.
RHS · read 13 September 2026
Pests and diseases
Can be troubled by aphids, mealybugs, and slugs and snails. Diseases: bacterial leaf spot.
NC State Extension · read 13 September 2026
Can be troubled by aphids, vine weevil, glasshouse thrips, mites, mealybugs and caterpillars. Diseases: rhizome rot, stem rot, powdery mildews and grey moulds.
RHS · read 13 September 2026

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About the plant

Begonia masoniana, the iron cross begonia, is a species of plant in the family Begoniaceae, native to southern China and northern Vietnam. It was originally described from cultivated plants of unknown origin and was only much later rediscovered in the wild.

From Wikipedia, CC BY-SA 4.0 · read 13 September 2026

Native range
China (Guangxi) to Vietnam
World Checklist of Vascular Plants, June 2026 release, CC BY.
Kew WCVP · read 13 September 2026
Eastern coast of China south to Vietnam
NC State Extension · read 13 September 2026
China, Vietnam
RHS · read 13 September 2026
Climate
wet tropical
World Checklist of Vascular Plants, June 2026 release, CC BY.
Kew WCVP · read 13 September 2026
Growth form
perennial or rhizomatous geophyte
World Checklist of Vascular Plants, June 2026 release, CC BY.
Kew WCVP · read 13 September 2026
Herbaceous Perennial; habit broad, dense, erect
NC State Extension · read 13 September 2026
Clump forming (evergreen)
RHS · read 13 September 2026
Size
Height 12–18 in; width 12–18 in
NC State Extension · read 13 September 2026
Height 0.1-0.5 metres; spread 0.1-0.5 metres after 5–10 years
RHS · read 13 September 2026
Flowering
Flowers green, white; blooms in spring, summer
NC State Extension · read 13 September 2026
Flowers green in summer; white in summer
RHS · read 13 September 2026

Other Begonia

More of the Begoniaceae family

Plants with similar care

Sources

What this does not cover

The figures above are what published sources say, not measurements of the plant in your room. They say nothing about your pot size, your water, the season, or how far from the glass the plant stands, and those decide more than any figure here does.

Humidity has no species figure because no source read for this site publishes one, and the only temperature published for this plant is a cold floor. The simulator fills those gaps with general figures for its kind of plant, marked as general and listed on how we read sources. Where a toxicity row says the plant was not assessed, that is the absence of a finding and not a finding of safety.

If something is already wrong, the diagnosis tool asks about the soil, the window and the watering, which is where the answer usually is.