How to care for a Begonia houseplant
Begonia spp.
Begonias span flashy foliage types and free-flowering kinds, but they share a temperament: bright indirect light, soil watered as the top dries, and dry leaves, because water sitting on the foliage invites powdery mildew. Keep them warm and never soggy. Their underground roots and tubers are the most toxic part to pets.
Care at a glance
- Light
- Bright indirect light, out of direct sunEnough light to keep colours and flowering strong, but direct midday sun scorches the often-delicate leaves. An east window or a bright interior spot suits them.
- Water
- When the top of the compost feels dryWater around the base, not over the crown, and let excess drain. They rot quickly if left sitting wet, and sulk if bone dry.
- Soil
- Light, open, peat-free houseplant compostAdd perlite for drainage; the fibrous or tuberous roots dislike dense, waterlogged mixes.
- Humidity
- Moderate humidity, but keep leaves dryThey like humid air, yet water on the foliage encourages mildew — raise humidity with a pebble tray, not misting.
- Temperature
- 15–24 °C (60–75 °F); avoid cold and dampCold, stagnant, damp air is the perfect storm for fungal problems.
- Difficulty
- ModerateRewarding but prone to mildew and rot if airflow and watering are not managed.
- Pets
- Toxic to petsToxic to cats and dogs — begonias contain soluble calcium oxalates that cause mouth irritation, drooling, and vomiting; the underground tubers and roots are the most toxic part (ASPCA).
Where it comes from
Propagation
Many begonias, especially the foliage rex types, propagate readily from leaf cuttings. Lay a healthy leaf on damp compost and pin it down, or cut it into wedges each containing a main vein and insert them upright; plantlets sprout from the cut veins. Keep them warm, bright, and humid under cover. Cane and shrub begonias root just as easily from stem cuttings in water or compost.
Common problems
- White, powdery patches on the leaves
Likely cause: Powdery mildew, encouraged by damp leaves, crowding, and poor airflow.
Fix: Water at the base only, improve air circulation, remove affected leaves, and avoid wetting the foliage.
- Stems and base turning soft and brown
Likely cause: Stem or crown rot from overwatering or water pooling at the centre.
Fix: Cut back on watering, improve drainage, and take healthy cuttings to save the plant if rot has spread.
- Leggy growth and few flowers
Likely cause: Too little light to support compact, flowering growth.
Fix: Move it to brighter indirect light and pinch back leggy stems to encourage bushier growth.
Frequently asked questions
Why does my begonia keep getting white powdery mildew?
Mildew thrives on damp leaves in still, crowded air. Water at the base rather than overhead, give the plant more space and airflow, and remove affected leaves promptly to stop it spreading.
What is the difference between a rex begonia and a flowering begonia?
Rex begonias are grown for their dramatic patterned foliage and flower only modestly, while types like the Rieger and wax begonias are grown chiefly for their abundant blooms. Care is broadly the same.
Are begonias poisonous to cats and dogs?
Yes. The ASPCA lists begonias as toxic — they contain soluble calcium oxalates that irritate the mouth and cause drooling and vomiting, with the underground tubers being the most toxic part. Keep them away from pets.
Should I mist my begonia to raise humidity?
No — misting wets the leaves and that is exactly what triggers powdery mildew. If the air is dry, stand the pot on a tray of moist pebbles to raise humidity without dampening the foliage.
Sources
- RHS — Begonia — Royal Horticultural Society, checked 2026-06-13
- ASPCA Toxic and Non-Toxic Plants — Begonia — ASPCA, checked 2026-06-13