Indoor Begonias : cultivation and care

Botany and description

The indoor begonia belongs to the botanical family Begoniaceae, a vast family comprising over 1,800 species. The genus Begonia derives its name from the French governor Michel Bégon, a passionate botanist in the 17th century, whom the botanist Charles Plumier wished to honour. In French, begonias are often simply called begonias, but some types bear more evocative names such as the bamboo begonia or the Begonia rex, famous for its spectacular foliage.

Botanical plates circa 1896: Begonia semperflorens and Begonia rex

In their natural habitat, begonias thrive primarily in tropical and subtropical regions, nestled in humid undergrowth where filtered light and constant humidity provide ideal conditions. This connection with shady and humid environments partly explains why they flourish so well indoors. Their great popularity as houseplants stems from several assets: their incredible diversity of forms and colours, ranging from decorative foliage to vibrant blooms, and their ability to adapt to moderate light conditions, perfect for living spaces. Easy to integrate into interior décor, begonias add a touch of exoticism and refinement while requiring relatively little maintenance.

Two distinct major families: foliage begonias and flowering begonias

Among indoor begonias, two major families stand out: begonias cultivated for their spectacular foliage and those prized for their delicate flowers.

Foliage begonias, often associated with the famous Begonia rex, are distinguished by their broad, colourful leaves, often featuring surprising patterns. Among the most sought-after varieties are the Begonia Rex ‘Escargot’, recognisable by its spiral leaves reminiscent of a snail’s shell, or the Begonia Rex ‘Chayo’, which shines with its bold and vivid hues. Other examples include the Begonia Rex ‘Red Heart’, with its deep and captivating red, the Begonia Rex ‘Dark Mambo’, with its almost mystical dark tones, and the Begonia Rex ‘Dew Drop’, which brightens interiors with its silver highlights. The Begonia maculata, with its elongated leaves adorned with white spots, is also an icon among decorative begonias.

Begonia rex ‘Escargot’ and Begonia maculata

On the other hand, flowering begonias captivate with their abundant and elegant blooms. Although less extravagant in their foliage, they more than compensate with their delicate and colourful flowers. The Begonia amphioxus offers fine, spotted foliage that harmoniously complements its small flowers. The Begonia ‘Pink Pop’, meanwhile, enchants with its pink blooms that add a touch of softness. The Begonia eliator, with its flowers resembling miniature roses, is another highly popular species. Finally, the Begonia semperflorens, also known as the bedding begonia, brings delicate and persistent flowers that brighten interiors with charming simplicity.

Botanical characteristics of the Begonia genus

The Begonia genus encompasses a great diversity of plants, with varied botanical characteristics but sharing common traits that make them easily recognisable and cherished.

Plant habit

Begonias display a wide variety of habits, ranging from compact and creeping species to more imposing and upright plants. The Begonia maculata, with its slender stems and pendulous wing-shaped leaves, can reach up to 60 cm in height, while the Begonia rex, more compact, forms a dense and low clump.

Begonias of all shapes and habits create a beautiful “jungle” ensemble

Root system

Begonias exhibit three main types of root systems: fibrous, tuberous, and rhizomatous. Rhizomatous begonias, like the Begonia rex ‘Escargot’, develop an underground system consisting of thick rhizomes that allow them to store reserves and produce new shoots. Tuberous begonias, such as the Begonia tuberhybrida, possess tubers, making them particularly suited to seasonal cycles of dormancy and growth. Finally, fibrous-rooted begonias, like the Begonia semperflorens, have fine and dense roots that adapt easily to various substrates.

Foliage

The foliage is undoubtedly one of the most emblematic traits of the genus. Begonia leaves are often asymmetrical, a unique characteristic in the vegetable kingdom. They display a variety of shapes, colours, and textures. For example, the Begonia maculata offers elongated leaves adorned with white spots, while the Begonia rex ‘Red Kiss’ showcases broad, velvety leaves marked with intense red patterns. The leaves can be smooth, puckered, or edged with serrations.

Flowering

Begonia flowers, often unisexual (plants bear distinct male and female flowers), vary in size and colour. Flowering begonias, like the Begonia eliator, produce spectacular blooms in shades ranging from white to bright pink, through red and orange. Each flower is composed of two to four coloured tepals, which can be single or double.

Flowering of the Begonia maculata

Seeds

Begonias produce extremely fine and light seeds, almost like dust. These tiny seeds, contained in small capsules, require specific conditions to germinate, including indirect light and constant humidity.

Did you know? Although primarily known as indoor or semi-tropical plants, some begonia species and varieties are hardy enough to be grown outdoors in the garden. This is the case for the Begonia grandis ssp. evansiana, which can tolerate temperatures as low as -10°C when well protected.

Planting in pots

When to Plant a Begonia in a Pot?

Spring is the ideal time to plant a begonia in a pot, as temperatures begin to warm and the risk of frost has passed. This coincides with the start of the begonia’s active growth season.

Which Substrate to Choose?

Begonias thrive in a light, well-draining substrate rich in organic matter. A potting mix specially designed for houseplants or a homemade blend of universal compost, turf, and perlite is perfect to prevent waterlogging. Adding compost can also enrich the mixture.

Where to Place the Pot?

Place the pot in a bright spot, but avoid direct sunlight, which can scorch the delicate foliage. Indirect light near an east- or north-facing window is ideal. If you’re growing a flowering begonia, such as Begonia eliator, ensure it receives enough light to encourage flowering.

Which Pot to Choose?

A terracotta pot is ideal, as it allows the roots to breathe and prevents excess moisture, which is common with begonias. The pot size should match the plant: choose one slightly larger than the root ball (about 2 to 3 cm wider in diameter). A pot that’s too large can retain too much water, risking root rot. Ensure it has drainage holes.

Begonia tuberhybrida

How to Plant the Begonia?

1. Place a layer of clay pebbles or gravel at the bottom of the pot to improve drainage.
2. Fill the pot halfway with the prepared substrate.
3. Position the begonia’s root ball, ensuring the collar (the base of the stems) is not buried.
4. Fill in around the root ball with substrate, lightly tamp it down, then water to moisten the mixture.

Potential Repotting

Begonias dislike being cramped, but they tolerate staying in their original pot as long as the roots aren’t overcrowded or the substrate isn’t too compacted. Repotting every 2 to 3 years, ideally in spring, is sufficient to refresh the substrate and give the plant more space. When repotting, choose a slightly larger pot and replace as much substrate as possible without damaging the roots.

Begonia hybrida ‘Gryphon’

Culture and maintenance

Watering

Watering should be moderate but regular. Begonias dislike excess water, which can lead to root rot. Allow the surface of the substrate to dry slightly between waterings, then water until the water drains out of the drainage holes. Use preferably room-temperature, non-calcareous water. In winter, reduce watering, especially for varieties that enter partial dormancy, such as some tuberous begonias.

Fertilisation

During the growth period (spring-summer), apply a liquid fertiliser for flowering or green plants every two to three weeks. Foliage begonias, such as Begonia rex, benefit from a nitrogen-rich fertiliser to support the growth of their decorative foliage. Flowering begonias, such as Begonia eliator, will appreciate a balanced or slightly potassium-enriched fertiliser to stimulate flowering. In autumn and winter, stop or reduce fertilisation.

Pruning

Pruning is rarely essential for begonias, but it can be useful to maintain a compact and harmonious plant. Remove yellowed, dry, or damaged leaves to prevent any risk of disease. For flowering begonias, regularly pinch off faded flowers to encourage the production of new blooms. For some varieties, such as Begonia maculata, pruning overly long stems can also promote denser branching.

Precautions to Take

• Light: Begonias appreciate indirect and soft light. Too much direct light can scorch their leaves, while insufficient light can hinder their growth and limit flowering.
• Humidity: They prefer a slightly humid atmosphere, but avoid misting the leaves directly, as this can cause fungal diseases. If the air is dry, place a tray of water with pebbles under the pot or use a humidifier.
• Temperature: Keep them in a temperate environment between 18 and 24 °C. Begonias dislike cold drafts or sudden temperature changes.

Tip for a long life: Rotate the pot regularly to prevent the plant from growing unevenly towards the light. Also, clean dusty leaves with a damp cloth to maximise their ability to absorb light.

Find out more with Leïla’s advice in: Indoor Begonias, Care Throughout the Seasons.

Begonia rex ‘Silver Dollar’

Potential Parasites and Diseases

Common Parasites

1. Aphids
   Aphids are small green, black, or yellow insects that settle on new shoots or under the leaves. They feed on the sap and weaken the plant, causing deformed or yellowed leaves. To learn more, read our advice sheet Aphids: Identification and Treatments.
   • Solution: Treat with a solution of diluted black soap in water.
2. Mealybugs
   Mealybugs are recognisable by their white, cottony clusters on stems or at the base of leaves. They also feed on the sap and weaken the plant. To learn more about mealybugs, read our advice sheet Mealybugs: Identification and Natural Treatments.
   • Solution: Remove them manually using a cotton swab soaked in 70° alcohol.
3. Spider Mites
   These tiny mites thrive in dry and warm environments. They cause yellowed leaves and sometimes a fine web of silk under the foliage. To learn more, read Spider Mites: Identification and Treatment.
   • Solution: Increase humidity around the plant and treat with a homemade solution of black soap.
4. Thrips
   These small, elongated insects feed on leaves, leaving silver spots and discolouration. To learn more, read Thrips: Identification and Natural Treatments.
   • Solution: Use blue sticky traps.

Common Diseases

1. Downy Mildew
   Downy mildew is a fungal disease that manifests as yellow or brown spots on leaves, often accompanied by a greyish down on the underside. It develops in humid and poorly ventilated conditions.
   • Solution: Avoid excessive watering and improve air circulation around the plant. Treat with a copper-based fungicide.
2. Powdery Mildew
   This disease, also caused by a fungus, forms a white powder on the leaves. It usually appears during strong temperature or humidity fluctuations. To learn more, read Powdery Mildew: Prevention and Treatment.
   • Solution: Remove affected parts and apply a natural fungicidal treatment, such as a diluted baking soda solution.
3. Root Rot
   This occurs due to overwatering or poor drainage. The roots turn black and soft, and the plant begins to wilt.
   • Solution: If the roots are affected, repot the plant in fresh soil after removing the rotten parts. Be careful not to overwater.
4. Bacteriosis
   Translucent, watery spots may appear on the leaves, caused by a bacterial infection favoured by stagnant humidity.
   • Solution: Remove affected leaves and avoid watering the foliage. Ensure good ventilation.

General Prevention

• Control Watering: Water moderately and only when the soil is dry on the surface.
• Improve Airflow: Place begonias in a well-ventilated area but protected from cold drafts.
• Regular Monitoring: Inspect leaves, stems, and the underside of leaves to detect early signs of parasites or diseases.
• Maintain Good Hygiene: Remove dead leaves and regularly clean the pot and its surroundings to prevent pest proliferation.

Propagation of Indoor Begonias

Foliage begonias, such as Begonia rex or Begonia maculata, are typically propagated by propagation by cuttings or division, easy and effective methods to reproduce these plants with unique foliage.

When to propagate?

The best time to propagate foliage begonias is in spring or early summer, when the plant enters its peak growth period and has optimal energy to form new roots.

How to propagate?

1. Leaf propagation by cuttings:
   • Take a healthy, well-developed leaf with its petiole (the stem connecting the leaf to the plant).
   • Cut the leaf into sections if it is large, ensuring each piece contains a main vein.
   • Plant the leaf sections or the petiole in a light mix of compost and sand, with the vein side down. Keep the substrate slightly moist and place it under a cloche or a transparent plastic bag to maintain constant humidity.
   • Roots and new seedlings will appear in a few weeks.
2. Stem propagation by cuttings:
   • Cut a healthy stem about 8-10 cm long with 2 to 3 leaves.
   • Remove the lower leaves, keeping only those at the top.
   • Plant the stem in a light substrate, water moderately, and place under a cloche or in a warm, bright spot, but out of direct sunlight.
3. Division of rootstocks (for rhizomatous begonias, such as Begonia rex):
   • Carefully dig up the mother plant and divide the rootstock into several sections, ensuring each piece has at least one bud or shoot.
   • Plant the sections in individual pots with fresh compost.

tuberous begonia

Propagation of indoor flowering begonias

Flowering begonias, such as Begonia eliator or Begonia semperflorens, are mainly propagated by stem propagation by cuttings or sowing, depending on the variety.

When to propagate?

Propagation of flowering begonias is ideally done in spring or summer, when they are in their active growth phase.

How to propagate?

1. Stem propagation by cuttings:
   • Take a healthy stem 8 to 12 cm long, just below a node, removing the lower leaves to keep only 2 or 3 at the top.
   • Plant the stem in a light and moist substrate (a mix of compost and sand or perlite).
   • Place the pot in soft light and under a cloche or plastic bag to maintain high humidity.
   • Roots usually form within 3 to 4 weeks.
2. Sowing (for Begonia semperflorens):
   • Sow the seeds on the surface in a very fine, well-draining mix, as begonia seeds are tiny and should not be covered with substrate.
   • Maintain a temperature between 20 and 22 °C, with constant humidity (place under a transparent plastic lid or in a mini greenhouse).
   • The seeds germinate in 10 to 20 days. Once the seedlings are large enough, transplant them into individual pots.

Tips for successful propagation

• Always use clean and disinfected tools (knives, scissors) to avoid spreading diseases.
• Provide your cuttings or seedlings with soft light and constant humidity, but avoid overwatering, which could cause rot.
• Be patient: some varieties, especially those propagated by sowing or leaf propagation by cuttings, take time to develop new roots or seedlings.

How to showcase your begonias?

Decorative-Leaf Begonias: A Graphic and Sophisticated Touch

Thanks to their vibrant colours and unique patterns, decorative-leaf begonias, such as Begonia rex or Begonia maculata, blend perfectly with modern, bohemian, or contemporary interiors.

• For which interiors?
  • Modern or minimalist style: These begonias add a touch of contrast and texture, especially in clean spaces dominated by neutral tones (white, grey, beige). The Begonia maculata, with its white spots on a green background, is particularly effective for adding character.
  • Vintage or retro style: Pair them with antique furniture or accessories in brass or copper for a warm ambiance. The Begonia Rex ‘Escargot’, with its hypnotic spirals, complements this type of décor beautifully.
  • Urban jungle style: In a room filled with plants, a Begonia rex ‘Red Heart’ or ‘Dark Mambo’ becomes a centrepiece thanks to its deep hues and lush appearance.
• In which type of pot?
  • Coloured or textured ceramic pots: Ideal for highlighting the intense tones and leaf patterns. For example, a midnight blue or emerald green ceramic pot pairs beautifully with a Begonia rex ‘Red Kiss’.
  • Natural terracotta pots: Perfect for a bohemian or jungle interior, as the material enhances the complex nuances of the foliage.
  • Open terrarium: Rhizomatous or compact begonias like the Begonia Rex ‘Dew Drop’ are ideal for compositions with mosses and other small plants, creating a mini tropical forest.

Begonia maculata

Flowering Begonias: Delicacy and Romance

Flowering begonias, such as Begonia eliator or Begonia semperflorens, bring a soft and warm ambiance thanks to their abundant and colourful blooms.

• For which interiors?
  • Classic or romantic style: The elegant flowers of the ‘Pink Pop’ begonia find their place in living rooms or bedrooms decorated with soft textiles, weathered wood furniture, and pastel tones.
  • Cottage or chic country style: The Begonia semperflorens, with their delicate and evergreen small flowers, are perfect for adding a bucolic note to a kitchen or dining area.
  • Warm contemporary style: Placed in bright spaces with neutral tones and a few colourful accents, flowering begonias like the Begonia amphioxus create a soothing focal point.
• In which type of pot?
  • Pastel ceramic or frosted glass pots: These containers enhance the softness and romance of pink, white, or red flowers. For example, a pale pink Begonia eliator will look stunning in a powder pink ceramic pot.
  • Elegant hanging planters: Trailing or slender-stemmed flowering begonias, like some hybrids, adapt perfectly to macramé or gold metal hangers for an airy decoration.
  • Wicker or rattan cache-pots: Ideal for a rustic or bohemian interior. The Begonia semperflorens, for example, find a natural setting that enhances their delicate blooms.

Tips for Incorporating Begonias into Décor

• Group staging: Combine several begonias of different varieties in matching or complementary pots to create a dynamic composition.
• Standalone centrepiece: Place an exceptional foliage begonia like the Begonia rex ‘Escargot’ or a flowering begonia like the Begonia eliator on a console or coffee table, in an elegant pot that draws the eye.
• In a bright corner: Position a Begonia maculata on a stand or shelf near a window to catch indirect light and play with its spotted reflections.

Begonia maculata