Rieger begonia

Rieger begonia (Begonia × hiemalis) is a winter-flowering hybrid sold as a short-term potted plant. Give it bright, filtered light from spring to fall and a few hours of direct sun in winter while it blooms. Keep it at 60 to 65°F (16 to 18°C) and never below 50°F (10°C). Water in the morning when the top inch of soil is dry, then empty the saucer after 15 minutes. Keep the leaves dry and the air moving. Feed every 2 to 4 weeks in active growth with a diluted bloom fertilizer such as 15-30-15.

Buy a Rieger begonia for months of winter color, not as a plant to keep for years. The New York Botanical Garden notes that most are kept as a temporary decoration and then discarded. If you want to try keeping one, take cuttings after bloom ends. If you want a begonia that lasts for years, an angel wing or rex begonia is a better pick.

Looking for a flowering plant to brighten things up? Try growing a Rieger begonia!

Rieger begonias (Begonia × hiemalis) are popular flowering houseplants with blooms in pink, red, orange, yellow, cream, and white. They are semi-tuberous hybrids, so they fit neither the fibrous Wax Begonias group nor the true tuberous group. They need bright, filtered light, cool rooms, and soil that dries a little between waterings.

So, if you have a Rieger begonia or want to purchase one, keep reading. This article will cover all the basics of Rieger begonia care, so your plant can thrive in your home!

Rieger begonia basics

Rieger Begonia (Begonia x hiemalis) is a hybrid between summer-flowering tuberous begonias and a rare winter-flowering fibrous-root species called Begonia socotrana. In addition, this hybrid plant is commonly called Hiemalis Begonia and Elatior Begonia.

Rieger begonias grow about 12 to 18 inches tall and wide in most containers. The flowers are large and often double or semi-double. Almost 500 cultivars exist, per NYBG, and plants are sold year round. Most people treat them as seasonal plants. They decline after a long bloom, so cuttings are the best way to carry a favorite forward.

Buying Rieger begonia plants

You can purchase Rieger Begonias at most garden centers and plant nurseries as well as online plant stores.

Rieger begonia plant care guide

Rieger begonias are not hard to keep in bloom, but they are less forgiving than many houseplants. The basics are bright light without hot summer sun, cool temperatures, careful watering, and dry leaves.

Watering Rieger begonia

Rieger Begonia thrives with moist, well-draining soil. In addition, soggy soil can lead to root rot and powdery mildew. So, it’s best to wait until the top layer of soil becomes dry before watering. You can check the soil’s moisture levels by sticking your finger in the soil. If it’s dry, go ahead and water your plant. If not, wait a few days and check again.

Overwatering can kill your plant, so it’s better to water less frequently than overwater your plant, especially in the winter. The sun isn’t as hot during the winter and doesn’t evaporate moisture as quickly. Cut back on watering during this time, so the soil doesn’t become soggy.

Light requirements for Rieger begonia

From spring to fall, NYBG recommends bright, filtered light with no direct sun, such as an east window or a spot back from a south window. In winter, while the plant is in bloom, move it close to a west or south window for a few hours of direct sun each day. Make the change over a week or so to reduce stress. Outdoors, grow it in partial shade so the leaves do not burn.

Fertilizer for Rieger begonia

Feed every 2 to 4 weeks while the plant is in active growth, using a diluted, water-soluble fertilizer such as 15-30-15, per NYBG. The higher middle number is phosphorus, which supports flowering. Too much fertilizer can burn the roots, so dilute it and water it in on moist soil.

Humidity & temperature for Rieger begonia

Rieger begonias prefer relative humidity above 50%. Raise it with a tray of moist pebbles under the pot or a humidifier nearby. NYBG also lists misting, but Penn State Extension advises keeping leaves dry to limit bacterial leaf spot and to space plants for airflow to limit botrytis. A pebble tray or a humidifier raises humidity without wetting the leaves.

NYBG recommends 60 to 65°F (16 to 18°C) to extend flowering, and no exposure below 50°F (10°C). Keep the plant away from heat vents and cold doors or windows. Good airflow helps prevent disease, so a fan on low can help, as long as it does not blow straight on the plant.

Repotting Rieger begonia

Since Rieger Begonias don’t live very long, you may not need to repot your plant. Rieger Begonias prefer to be a bit rootbound, so you only need to repot if you want to. 

Potting soil for Rieger begonia

Rieger Begonias prefer well-draining, airy soil. Peat moss and perlite or sand is the perfect soil combination for these plants. Perlite and sand break up the soil and allow adequate drainage, whereas peat moss maintains moisture. Having a balance of moisture and drainage in your plant’s soil prevents the plant from developing root rot as well as drying out. 

Planter pots for Rieger begonia

You can plant your Rieger Begonia in a hanging planter or a pot with adequate draining holes. For example, you can use plastic or terracotta pots for Rieger Begonias. Plastic pots retain more moisture, so you need to be careful when watering your plant. On the other hand, clay terracotta pots wick away moisture, keeping the soil more dry, which works well for Rieger Begonias. 

Propagating Rieger begonia

You can propagate Rieger begonias from stem cuttings. NYBG suggests taking cuttings once flowering has finished. To propagate your plant:

1. Use clean, sharp scissors to cut a 3-inch stem tip just below a leaf node. Roots form at the node.
2. Let the cutting sit for a few days so the cut end can callus. NYBG suggests a longer rest of up to 10 days.
3. Dip the end in rooting hormone if you like, then plant it in a light, moist potting mix and set it in bright, indirect light.

Cuttings root best in humid air. Cover the pot with a clear plastic bag and open it for a while each day to let fresh air in. Keep the cutting warm and out of direct sun until new growth shows that roots have formed.

Common pests affecting Rieger begonia houseplants

The common pests affecting Rieger Begonias are spider mites, aphids, mealybugs, and scale. These pests attack the plant by sucking the sap from its leaves. Leaves that wilt, curl, or yellow can be a sign of an infestation. If you’re not sure whether these pests infested your plant, check the bottom of the leaves, as this is where these pests like to hide. In addition, the leaves may feel sticky from honeydew, a sugary waste the insects leave behind.

If you have an infection, quarantine your plant and remove any dead leaves. Then, spray the plant with a gentle insecticide or a diluted rubbing alcohol and water mixture. For pests like scale, you can spray rubbing alcohol on a paper towel and wipe the infected leaves.

Common diseases affecting Rieger begonia

Rieger begonias are prone to powdery mildew, botrytis, bacterial leaf spot, and root rot, per Penn State Extension. White powder on leaves is powdery mildew. Tan spots with gray fuzz are botrytis, so remove dead flowers and leaves and improve airflow. Water-soaked spots with yellow halos point to bacterial leaf spot. Penn State advises discarding infected Rieger types, since the infection spreads through the whole plant. Collapsing stems at the soil line point to root rot from overwatering.

Rieger begonia FAQ

How long do Rieger begonias live?

Most are grown as short-term plants and discarded after their long bloom. Taking cuttings after flowering is the best way to keep a favorite going.

How often should I water a Rieger begonia?

Water in the morning when the top inch of soil feels dry, then empty the saucer after 15 minutes. Soggy soil leads to root rot.

What temperature does a Rieger begonia need?

Aim for 60 to 65°F (16 to 18°C) to make flowers last. Do not let it drop below 50°F (10°C), and keep it away from drafts and heat vents.

Can Rieger begonias go outside?

Yes, in partial shade during warm months. Bring the plant indoors before nights drop toward 50°F (10°C).

Why are my Rieger begonia leaves turning yellow?

NYBG lists too little light and over or under watering as the usual causes. Check the soil before watering and move the plant to brighter, filtered light.

References

• New York Botanical Garden, Winter-flowering begonia (Begonia × hiemalis) houseplant care
• Penn State Extension, Begonia diseases