Rex begonia (Begonia rex) care

Begonias & violets · needs attention to keep

Rex begonia (Begonia rex) wants bright indirect light. Water it every 5 days. Water when the top of the compost is dry, around the edge of the pot rather than over the leaves. Water sitting on a begonia leaf overnight is how mildew starts. Pot it in light, airy, free-draining compost with perlite and bark. A balanced feed at half strength every two to four weeks in spring and summer, and repot once a year. Humidity: above 60%, but with air moving — still humid air gives them mildew. Toxic to cats and dogs — the tubers most of all.

The painted-leaf begonia: grown entirely for foliage in metallic silver, purple, pink and near-black, often spiralled at the base of the leaf. It grows from a rhizome on the surface, is short-lived by houseplant standards, and is propagated from a single leaf — which is how collections spread.

Quick facts

Water: Water every 5 days. Water when the top of the compost is dry, around the edge of the pot rather than over the leaves. Water sitting on a begonia leaf overnight is how mildew starts.
Light: Bright indirect light.
Humidity: Above 60%, but with air moving — still humid air gives them mildew.
Soil: Light, airy, free-draining compost with perlite and bark.
Feeding: A balanced feed at half strength every two to four weeks in spring and summer.
Repotting: Repot once a year.
Toxic to pets: Toxic to cats and dogs — the tubers most of all. Causes mouth irritation and vomiting.
Difficulty: Needs attention.
Mature size: 25–40 cm tall and wide.
Native to: Northeast India; the group is a vast set of hybrids.

Watering a Rex begonia

Water every 5 days. Water when the top of the compost is dry, around the edge of the pot rather than over the leaves. Water sitting on a begonia leaf overnight is how mildew starts.

That cadence is the one PlantParlour sets for this species when you name it, and it is deliberately on the cautious side — a plant that asks a day early is safer than one that asks a day late. Log each watering and the reminder moves with the plant rather than with the calendar.

Light

Bright indirect light. Begonias want brightness without a ray of direct sun landing on the leaves, which mark permanently.

Humidity and temperature

Above 60%, but with air moving — still humid air gives them mildew. Central heating in winter is what turns a comfortable room into a dry one, and it is the usual reason an established plant suddenly browns at the edges or picks up spider mites.

Soil and potting

A light open mix. Begonia roots are fine and shallow and rot readily; many growers use a shallow pot and an aroid-style mix.

Feeding

A balanced feed at half strength every two to four weeks in spring and summer. Stop feeding in autumn and start again when you see new growth in spring — feeding a plant that isn't growing just builds up salts in the pot.

Repotting

Repot once a year. Every spring, into a shallow wide pot. Cane begonias get top-heavy and want staking.

Common problems

White powdery patches on the leaves
Powdery mildew — humid air with no movement.

Fix: Improve airflow, stop watering over the leaves, remove affected leaves, and treat if it spreads.
Leaves dropping suddenly
A cold draught or a dry spell.

Fix: Keep it above 15 °C and evenly damp.
Leggy stems with leaves only at the top
Not enough light.

Fix: Move it brighter and cut back hard in spring — cane begonias respond well.
Brown crisp edges
Dry air.

Fix: Raise humidity, keeping the air moving.

Propagation

Leaf cuttings: pin a leaf flat on damp compost with the veins nicked, and plantlets form at the cuts. Stem cuttings root in water.

A cutting taken in PlantParlour keeps its link to the plant it came from, so a propagation years later still traces back to the mother plant — which is the point if you ever sell or trade it.

Toxicity and safety

Toxic to cats and dogs — the tubers most of all. Causes mouth irritation and vomiting.

Questions people ask

How often should you water a Rex begonia?

Water every 5 days as a starting point — that is the cadence PlantParlour sets for Begonia rex. Water when the top of the compost is dry, around the edge of the pot rather than over the leaves. Water sitting on a begonia leaf overnight is how mildew starts. Light, pot size and the time of year all move that number, so treat it as a reminder to go and check rather than a rule.

How much light does a Rex begonia need?