Rex Begonia is grown for its leaves, not its flowers: large, asymmetrical leaves in swirls of silver, pink, red, purple and green, with patterns that look painted on. No two varieties look alike, and the foliage is so vivid that the plant works as a living piece of art on a tabletop or shelf.
It is a rhizomatous begonia, growing from a thick horizontal stem at the soil surface, and it stays compact and low rather than climbing or trailing. That low, spreading habit makes it a good choice for a bright shelf or a terrarium, where its colours can be seen up close. Wet leaves are the enemy. Rex begonia leaves mark and rot easily if they stay wet, and powdery mildew follows wet foliage and still air — so how you water matters as much as how often. This guide covers exactly what it needs: light, watering, humidity, temperature, soil, repotting, feeding, propagation and the common problems that show up when something is off.
Rex Begonia at a glance
| Care factor | What this plant needs |
|---|---|
| Botanical name | Begonia rex-cultorum |
| Light | bright indirect |
| Water | weekly; keep soil lightly moist, avoid wet leaves |
| Humidity | moderate to high |
| Temperature | 65–75°F (18–24°C) |
| Repotting | every 1–2 years |
| Pet safety | toxic to cats and dogs |
Light
Give your Rex Begonia bright indirect. Bright indirect light keeps the colours vivid — in too little light the patterns fade and the plant stretches. Avoid direct sun, which can scorch the thin leaves and bleach the colours, and avoid a dark corner, which turns the plant leggy and dull. An east-facing window, or a little back from a south-facing one, suits it well. Our grow-light calculator can help work out whether your spot is bright enough, and our sunlight calculator can help you check how much light a window really gets through the day.
Watering
Water as follows: weekly; keep soil lightly moist, avoid wet leaves. Water weekly and keep the soil lightly moist, but water at the base of the plant and keep the leaves dry. Water thoroughly until it runs from the drainage holes, then empty the saucer. Let the top of the soil dry slightly between waterings — Rex begonia rots fast in soggy soil — and use room-temperature water, since cold water can mark the leaves. Our watering calculator gives a starting point for your pot size, and the watering schedule generator can help you build a routine around it.
Humidity and temperature
Rex Begonia needs moderate to high humidity and temperatures of 65–75°F (18–24°C). Rex begonia likes moderate to high humidity, and dry air shows as brown, crispy leaf edges. Grouping plants together or a pebble tray helps, and a humidifier is the reliable fix in a dry heated home. Do not mist the leaves to raise humidity — wet leaves invite mildew, which is this plant's biggest problem. Our humidity and temperature checker can tell you whether your room suits this plant. Temperature matters just as much as humidity: keep it away from cold windows in winter, from radiators that dry the air, and from air-conditioning vents that blast cold air directly at it.
Soil and potting
Indoors, this plant needs a rich but very free-draining potting mix. A light, airy, free-draining mix suits it: potting soil with perlite and a little coco coir or bark. The rhizome sits at the surface, so plant it shallowly — burying the rhizome invites rot — and use a pot with drainage holes. A shallow, wide pot often suits the spreading habit better than a deep narrow one. Our potting-mix calculator can work out the parts for a homemade mix for your pot size, and our soil volume calculator can work out how much mix you will need.
Repotting
Repot every 1–2 years, in spring, or sooner if roots are circling the drainage holes. Repot in spring when the rhizome reaches the edge of the pot or roots fill the pot, moving up only one pot size. Repotting is also the moment to divide the rhizome — see Propagation below. Handle the plant gently: the leaves are thin and snap easily, and the rhizome bruises if squeezed. Our repotting calculator can help you work out the next pot size and how much fresh mix you will need.
Feeding
Feed during the growing season, in spring and summer, with a balanced liquid houseplant fertiliser at half the strength on the label, roughly once a month while the plant is actively growing. Feed in spring and summer with a balanced liquid fertiliser at half strength, about once a month while it is actively growing. Rex begonias are light feeders, and excess fertiliser burns the leaf edges, so less is more. Do not feed in autumn and winter when growth slows. Our fertiliser calculator can help you work out the right amount for your pot size. Always follow the directions on the label — more fertiliser is not better, and excess salts build up in the soil and burn the roots.
Propagation
Rex Begonia is propagated from leaf cuttings and by dividing the rhizome. For leaf cuttings, take a healthy leaf with its stalk, or cut a leaf into sections, and press the pieces onto moist, free-draining mix, keeping them warm and humid until plantlets form at the cut veins — this takes several weeks. For division, cut the rhizome into pieces when you repot, each piece with at least one growing point, and pot them separately. Keep new cuttings out of direct sun and keep the mix lightly moist, not wet, while they root.
Common problems and fixes
| Problem | Likely cause | Fix |
|---|---|---|
| Powdery mildew | wet leaves and poor air flow | Keep leaves dry; improve airflow and remove affected leaves. |
| Brown leaf edges | low humidity | Raise humidity; trim brown edges with clean scissors. |
| Dropping leaves | overwatering or cold | Check soil moisture and cold draughts; keep watering steady and the plant settled. |
Powdery mildew
Likely cause: wet leaves and poor air flow. Powdery mildew shows up as a white, powdery coating on the leaves, and it thrives where leaves stay wet and the air does not move. Water at the base of the plant, never over the leaves, and give the plant space and gentle air circulation so the foliage dries. Remove badly affected leaves, improve airflow, and keep the leaves dry — mildew spreads fast in still, damp air, so early action matters. Our plant disease checker can help confirm what you are looking at.
Brown leaf edges
Likely cause: low humidity. Brown, crispy leaf edges are almost always a humidity problem, and they are the most common complaint with this plant. Dry indoor air, especially in a heated home in winter, dries the leaf margins faster than the plant can replace the moisture. Raise the humidity around the plant with a humidifier or by grouping plants together, and trim the brown edges with clean scissors, following the shape of the leaf — do not cut into healthy green tissue. Brown edges will not heal, but new leaves should come through clean once the air is moist enough.
Dropping leaves
Likely cause: overwatering or cold. Dropping leaves usually mean the plant is stressed by overwatering or by cold. Check the soil first: if it is soggy, let it dry out and check that the pot drains freely. If the soil is fine, look for cold — a draught, a cold window, or a sudden move to a much cooler spot can all make this plant shed leaves. Move it somewhere warm and settled, keep watering steady, and it should stop dropping leaves once it settles; new growth follows in the growing season.
Frequently asked questions
How often should I water Rex Begonia?
weekly; keep soil lightly moist, avoid wet leaves. Water weekly and keep the soil lightly moist, but water at the base of the plant and keep the leaves dry. Check the soil with your finger before you water — the surface can look dry while the soil below is still wet, and the plant's needs change with the season, the pot size and the light.
How much light does Rex Begonia need?
It needs bright indirect. Bright indirect light keeps the colours vivid — in too little light the patterns fade and the plant stretches. Too little light gives stretched, pale growth, and harsh direct sun — where it is not wanted — scorches the leaves.
Is Rex Begonia safe for cats and dogs?
According to the data used for this guide, this plant is toxic to cats and dogs. Keep it out of reach of pets that chew plants, and if a pet eats any of it, contact your vet.
Why are the colours on my Rex Begonia fading?
Usually too little light, or the plant is past its best. Bright indirect light keeps the patterns vivid; in a dim spot the colours wash out and the leaves turn greener. Move it to a brighter spot and judge by the new leaves. Rex begonias also age — an old plant with tired leaves can be refreshed by propagation from a healthy leaf.
What should I do if my Rex Begonia looks unhappy?
Start with the basics: check the soil moisture, the light, and the temperature, and look at the problems table above. Most unhappy houseplants are unhappy about water, light or cold, not about a rare disease — fix the care first, give the plant a few weeks, and judge it by the new growth, not by the damaged leaves, which will not heal.