Begonia sizemoreae (Sizemore's begonia) care

Light

Begonia sizemoreae is what florists mean by "bright spot, no direct sun" — close enough to a south or east window to feel the brightness, with a sheer curtain or a few feet of distance keeping the sun off the leaves. Give it bright, indirect light to keep growth compact and the hairs prominent. Direct midday sun burns the foliage, while deep shade makes it leggy. A spot near an east window or under grow lights works well. A phone lux-meter at the leaf surface should read 1,500-3,000 lux at noon.

Watering

Water begonia sizemoreae when the top 1-2 cm of mix dries slightly, about every 5-7 days. The actual day count varies with pot size, light, and season — the finger test (or lifting the pot to feel its weight) is more reliable than a fixed calendar. Empty any drainage saucer afterwards so the pot isn't sitting in water. Water once the surface has just dried, keeping the rhizome and crown from sitting wet. The hairy leaves dislike prolonged surface moisture, so water at the soil and let it drain. Ease off in winter.

Soil and pot

Begonia sizemoreae grows best in light, organic, free-draining begonia mix. Use a loose blend of coco coir or peat with perlite and a little bark or sphagnum so the rhizome stays oxygenated. Avoid heavy soils that hold water around the crown. Slightly acidic suits it best. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Begonia sizemoreae sits happiest at around 60-80% humidity and 18-28°C (65-82°F). High humidity, ideally around 70% by day, keeps leaves full and prevents edge browning; it appreciates even higher humidity at night. A terrarium, garden room, or large humidity setup is ideal, but always pair it with good air circulation to avoid fungal disease. If you keep the room above 18 year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed begonia sizemoreae sparingly. Feed every 3-4 weeks in the growing season with a balanced liquid feed at half strength. This is a vigorous begonia, so steady light feeding supports its fast growth; stop feeding in winter. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on begonia sizemoreae in the Growli community. Each is annotated with the most common cause so you know where to start.

• Browning leaf margins — Low humidity is the usual cause. Raise humidity toward 70% with a terrarium or humidifier.
• Crown or rhizome rot — Overwatering or a soggy crown rots the rhizome. Use airy mix, water only when the surface dries, and keep the rhizome on the surface, not buried.
• Powdery mildew — Common in humid, still air. Improve airflow and avoid wetting the hairy leaves when watering.
• Leggy, sparse growth — Insufficient light stretches the plant. Move to brighter indirect light or supplement with a grow lamp.

Propagation

Easily propagated by rhizome division or by leaf and stem cuttings; root in moist sphagnum or a humid propagator. It is one of the faster jewel begonias to multiply. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Begonia sizemoreae is toxic to pets. The ASPCA lists Begonia as toxic to cats and dogs; the toxic principle is soluble calcium oxalates, with the most toxic part underground (rhizome/tubers). Signs of ingestion include vomiting and salivation, with kidney effects in grazing animals. Keep away from pets. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Begonia sizemoreae deep-dive guides

Every aspect of begonia sizemoreae care, each with its own calibrated guide:

• Begonia sizemoreae watering schedule
• Begonia sizemoreae light requirements
• Best soil mix for begonia sizemoreae
• Begonia sizemoreae fertilizing guide
• When to repot begonia sizemoreae
• How to propagate begonia sizemoreae
• Begonia sizemoreae growth rate & size
• Begonia sizemoreae cold hardiness
• Begonia sizemoreae temperature & humidity
• Is begonia sizemoreae toxic to cats & dogs?
• Is begonia sizemoreae toxic to cats?
• Is begonia sizemoreae toxic to dogs?

Featured in these plant shortlists

Begonia sizemoreae qualifies for 5 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best plants for a north-facing window — Houseplants for a north-facing window: bright, even, indirect light and no scorching direct sun. Each pick verified against its documented light needs.
• Best humidity-loving houseplants — Houseplants that thrive in a bathroom, kitchen, or by a humidifier — selected by documented humidity preference.
• Houseplants toxic to cats & dogs — The common houseplants the ASPCA lists as toxic to cats and dogs — the ones to keep out of reach, each with its symptoms and a safe alternative.
• Best small & tabletop houseplants — Compact houseplants that stay under about 40 cm — desk, shelf and windowsill plants that never outgrow a small space.
• Best fast-growing houseplants — Houseplants documented as fast or vigorous growers — quick to fill a pot, cover a pole or trail down a shelf.
• Browse all 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Begonia sizemoreae is also commonly called Sizemore's begonia.

• Types of begonia — varieties identified, with care and pet-safety
• Snake plant care — light, water and common problems
• Dracaena care — light, water and common problems
• Peperomia care — light, water and common problems
• All 3899 plant care guides in the Growli library