Begonia Care Indoors: Rex, Cane and Rieger Types

Begonia care indoors depends on which begonia you have. There are well over a thousand species and thousands of hybrids, but most houseplant begonias fall into a few groups: rex begonias grown for patterned leaves, cane begonias such as the polka dot Begonia maculata, rhizomatous begonias, and flowering types such as Rieger (Elatior) begonias. All share a dislike of soggy soil and wet leaves, and a liking for bright, indirect light. Here's how to grow each group well.

Begonia care at a glance

UF/IFAS Gardening Solutions gives an overview of begonia groups and their needs.

Begonia types compared

Light

Most begonias like bright, indirect light: an east window, or a little back from a south or west window. Rex and rhizomatous begonias tolerate medium light, but leaves lose some colour and the plant gets leggy in dim spots. Flowering types need the most light to keep blooming, and enjoy an hour or two of gentle morning sun. Hot afternoon sun through glass scorches begonia leaves quickly. Measure your spot with the plant light meter converter.

Watering

Begonias have fine roots that rot easily. Water when the top 2 cm is dry, give a thorough drink, and let excess drain. Water at the soil, not over the leaves; wet foliage, especially in cool or still air, encourages powdery mildew and leaf spots. Bottom watering works well for begonias; see bottom watering plants.

The plant watering schedule builder and overwatered plant signs help get the balance right.

Soil and pots

Use a light, airy mix: peat-free houseplant compost with about a third perlite works well. Begonias prefer a snug pot, so move up only one size when roots fill it, and choose shallow pots for rhizomatous and rex types, which have shallow roots. Always use drainage holes. See houseplant soil mix and the repotting pot size calculator.

Humidity and air flow

Begonias enjoy moderate humidity, around 50 percent, especially rex types, which get crispy edges in dry air. But they also need air movement: high humidity with stagnant air invites powdery mildew. Group plants and use a humidifier rather than misting the leaves. A room fan on low, or a slightly open window in summer, keeps air moving. Check your room with the plant humidity checker.

Temperature

Keep begonias at 18 to 24°C. They dislike cold draughts and temperatures below about 13°C, and react to sudden changes by dropping leaves or buds.

Feeding

Feed every two to four weeks in spring and summer with a balanced liquid fertiliser at half strength. For flowering types, a fertiliser with a little more potassium (like a tomato feed at half strength) supports flowers. Cut back in winter. Use the fertilizer dilution calculator.

Caring for each type

Rex begonias. Keep in medium to bright indirect light, moderate humidity, and evenly moist (not wet) soil. Many rex begonias slow down or partly rest in winter; water less and don't feed. Remove flower stalks if you want to focus energy on leaves, and turn the pot weekly for even colour.

Cane begonias (polka dot begonia). Bright, indirect light and a stake for tall stems. Pinch the tips in spring to encourage branching, and cut old, bare canes back to a few centimetres to renew the plant. They flower on and off through the year.

Rhizomatous begonias. The easiest group. They grow from thick stems running along the soil surface. Plant them shallowly in wide pots and let the top of the soil dry a little more between waterings.

Rieger begonias. Bought in flower, they bloom for weeks in bright light. Deadhead spent flowers, water at the base, and keep air moving. Many people treat them as long-lasting cut flowers; they're hard to rebloom indoors.

Propagation

For rex leaf cuttings, lay a mature leaf face-up on moist mix, make small cuts across the main veins, pin it down, and cover loosely with a clear bag. Plantlets form at the cuts. See how to propagate houseplants.

Common problems

General pest advice is in houseplant pests, and leaf symptoms are covered in plant leaf problems.

Bringing outdoor begonias inside for winter

Wax and cane begonias grown in summer containers can be overwintered indoors. Before the first frost, check them carefully for pests, trim them back by about a third, and pot them into fresh mix if needed. Place them in your brightest window and water sparingly; growth slows a lot in winter. Expect some leaf drop as they adjust, and resume normal watering and feeding once new growth starts in spring. Tuberous begonias are handled differently: let the foliage die back in autumn, lift or keep the tubers dry in their pot in a cool, frost-free place, and restart them in spring.

Pet safety

The ASPCA lists begonias as toxic to cats, dogs and horses. The tubers and underground parts are most toxic, and the plant contains insoluble calcium oxalates that cause oral irritation, drooling and vomiting. Keep begonias out of reach of pets, and check other plants with the plant toxicity checker. For safer choices, see pet-safe houseplants.

Seasonal care

Bottom line

Indoors, begonias need bright, indirect light, a light mix in a snug pot, careful watering at the soil, moderate humidity with good air flow, and warmth. Learn which type you have, follow its specific needs, and you'll have striking leaves or flowers for years.

Sources: UF/IFAS Gardening Solutions, Begonias; ASPCA, Begonia.