Rex Begonia Care Guide: How to Grow Rex Begonia Indoors

The flamboyant foliage of the Rex begonia plant is an eye-catching choice for a houseplant. Their rich, variegated foliage is a great way to bring color and interest into your home. You can also grow them as part of a container garden or, in flower beds and borders. When planted in the ground they are classed as annual plants.

Unfortunately while Rex begonias may be attractive they are also very demanding. Requiring the right level of attention, many people can struggle to successfully keep a Rex begonia.

This guide will teach you everything you need to know to successfully care for a growing Rex begonia plant.

Rex begonia’s eye-catching leaves make it a popular houseplant. Rex begonias can also be successfully grown in a container garden or, in warm climates, a good bedding plant. 

Warning

The Rex begonia plant contains soluble calcium oxalates. This substance is toxic to cats and dogs.

Different Rex Begonia Plant Varieties

Depending on the cultivar, the Rex begonia plant can reach from 12 to 24 inches in height and spread. The clumping growth habit of Rex Begonias, coupled with their tightly packed leaves, makes for a dense plant.

There are many different varieties of Rex begonia, including hybrid varieties, available. The different cultivars produce leaves in a range of shapes and shades, including green, silver, red, pink, purple and orange. This means that you have lots of choice.

Before purchasing your plant research the cultivar’s specific needs. This enables you to find a plant that not only appeals to you but also suits your growing conditions.

One of the most attractive is the cultivar Snow Queen. This produces distinctive leaves that are silver in color. It is also pleasingly disease resistant. Another cultivar with silver foliage is Fireworks. Its attractive leaves are etched with purple markings. Begonia Rex Escargot is a particularly attractive variety. As the name Begonia Rex Escargot suggests, the spiraled markings of the foliage of Begonia Rex Escargot resembles the shell of a snail. The Begonia Rex cultorum is very popular.

Begonia Rex has many different cultivars that all present beautiful, interesting and unique foliage. This helps to make up for the Begonia Rex plant’s insignificant flowering habit. 

The cultivar River Nile produces beautiful luscious green leaves that are edged in deep bronze. This makes for an understated but attractive display. Cowardly Lion is another attractive cultivar, producing beautiful golden leaves with chocolate colored veining. As the plant ages the colors of the leaves become more intense.

Finally, the cultivar Stained Glass produces eye-catching ruby red leaves, the edges of which are pewter in shade. Adding to the visual display, dark veining marks the center of the leaf.

How to Grow Rex Begonia Plants

Rex begonias are perennial around tropical and semitropical climates. Rex Begonias are also sensitive to frosts. Rex begonias are hardy around USDA zones 10 and 11. This means that around North America zones 10 / 11 Rex Begonias are usually grown as houseplants.

You can also grow them outside as annuals or in containers. Just remember to move the Rex Begonias inside before the temperatures begin to fall.

This is a houseplant that is mainly grown for its foliage. However the flowers of Rex Begonias, which are often dismissed as being insignificant, have a delicate charm of their own. 

While the leaves of these plants are varied and interesting the flowers can seem incidental. The flowers of Rex Begonias are usually pink in color. Many growers tend to cut the flower stalks away. This encourages the plants to focus more of their energy on producing rich and interesting displays.

How to Transplant

Plants growing in containers require repotting every year. The best time to do this is in early spring, as they awake from their dormant period.

Regular re-potting ensures that the plants have lots of fresh, rich soil to develop in. It also prevents them from becoming pot bound. This can stunt growth and lead to disease. You may also want to transplant soon after purchasing.

Your chosen container should be clean and have drainage holes in the bottom. It should be as large, or slightly larger, than the container currently holding the plant. Remember soil in clay or terracotta plant pots dries out quicker than soil in plastic pots. So, depending on your choice of container, you may need to water them more frequently.

Regularly re-potting your houseplants helps to keep them healthy. It also promotes fresh growth and prevents them from becoming pot bound. 

Fill the container about a quarter full with fresh, well draining general purpose potting mix. Rex begonia plants do best in light, rich soil. A peat-based mix is ideal. Alternatively the plants also thrive in potting mixes designed for African violets.

Gently remove the plant from the container. Handle the root system with care. Rex begonia root systems are very delicate. Over handling can cause the plants stress and, in the worst cases, can cause them to die.

Place the plant in the center of the new container. Fill in the container with more fresh potting mix for the Rex Begonias, gently firming the soil.

Water until water drains from the drainage holes in the bottom of the pot.

How to Care for Rex Begonia Plants

Rex begonia plants have a reputation for being demanding. However, if you can find a position that Rex Begonias favor, they will cause you little trouble.

The plants thrive when placed in the bright indirect light of an east or west facing window. In cooler USDA zones a south facing window is also favorable.

Rotate the container every week. This enables the entire plant to receive similar bright indirect light levels. In darker houses try placing the plant under grow lights.

If the leaves begin to brown, or appear burned, it is a sign that the plant is too close to the window.

Rex Begonias that develop a leggy, or gangly, growth habit may be reaching towards the light. This is a visible sign that the plant is not getting enough light.

Outside, Rex begonias do best in partial shade positions. They also grow well in full sun positions but keep them out of direct light. Indirect light is best, this helps the plants to retain their interesting color.

Watering and Feeding

Water when the soil feels dry. During the plant’s dormant, winter period, reduce watering.

Begin fertilizing Rex begonia plants when they begin to grow in the spring. A general purpose houseplant feeder is ideal. Water soluble feeds are easily incorporated into your watering routine. Alternatively you can make your own plant feed. These are just as effective as commercial products.

Continue to fertilize once a fortnight during the growing period.

Don’t overfeed, this can cause the plants to become leggy. During the dormant, winter period cease feeding completely.

Regular fertilizing can, sometimes, cause salt to build up in the soil. This can harm the plants. Flushing the soil once every four months will wash away any salt that may be building up. Making your own plant feed allows you to know exactly what you are putting into your soil. This can help you monitor and prevent salt build up.

Rex Begonia Care – Temperature and Humidity

Rex begonias are sensitive to temperature and humidity changes. Houseplants do best when the temperatures range between 60 and 85 °F. Rex begonia ceases growing if the temperatures fall below 58 °F – be mindful in the winter months.

Remember to bring Rex Begonias growing outside indoors before the first frost. They also require high humidity levels.

Maintaining relatively high humidity levels helps to keep them healthy. Avoid dry air. If you are growing in containers cluster them together on a pebble tray filled with water. This creates a high humidity environment with minimal dry air. Don’t spray the leaves of the plant. This can create uneven humidity levels and lead to spotting.

Pruning

Rex begonias require little regular pruning. Cut back any bare stems. This helps to encourage a fuller plant to emerge. Pinching out the tips of young plants will also encourage fuller growth.

When pruning, always use clean secateurs or scissors. Your chosen implement should also be as sharp as possible. This helps you to make clean, precise cuts. 

Winter Rex Begonia Care

As temperatures fall in the winter months the plant’s growth habit will cease and it will enter a dormant period. This is perfectly natural, fresh growth will emerge the following spring.

This dormant period is also the ideal time to tidy up your plants. Remove any brown or unhealthy leaves and unsightly stalks.

If you are growing in containers outside move them inside as the temperatures begin to fall. This should be long before the first predicted frost date of the season.

Plants in unheated conservatories or greenhouses may benefit from an application of mulch onto the top soil. Mulch helps to keep the root system of the plant warm as well as helping the soil to retain moisture. If you choose to apply an organic mulch this will slowly break down, enriching the soil and further benefiting your plant.

Common Pests and Problems

Pests such as aphids, caterpillars and mealybugs can all attack Rex begonia plants. An application of neem oil or insecticidal soap will clear most infestations. Pests can also be removed with a blast of water from a hosepipe.

Wet leaves can develop bacterial leaf spot, botrytis or mildew. To prevent this water early in the day, giving the leaves time to dry before the cooler evening temperatures arrive. Also try to water just the base of the plant. This helps to keep the leaves dry.

If the soil is too wet Rex begonia can also develop root rot.

How to Propagate

Rex begonia propagation is possible but it is a slow process. It is best done from leaf cuttings

Clean a sharp scissors or small garden pruner. To sanitize the implement, wipe it with a solution that is at least 70% ethanol or isopropyl alcohol.

With a clean cut remove a healthy leaf. Trim the stem down, as close to the leaf as possible.

Once the cutting has been taken they are a couple of ways you can prepare it before placing it in the rooting medium. The easiest method is to keep the leaf intact. With a knife make several slashes across the underside of the leaf vein.

Press the leaf, with the cuttings face down, gently onto the rooting medium. Use small pebbles or weights to hold the leaf in place.

Alternatively, you can cut the leaf into sections. Each section should have a primary vein. Place each section in the rooting medium, ensuring the veins are at least partially covered.

Your rooting medium should be a soiless mix such as vermiculite or perlite. Peat moss can also be used. Potting soil may be too rich in nutrients. This can rot the leaves and burn any developing roots. Fill a plastic cup or other clear container with your chosen medium. Moisten the soil, it should be completely damp, not soggy.

After positioning your leaves put the container in a plastic bag. This helps to maintain humidity levels, encouraging roots to form. Place in a light position, away from direct sun. Regularly check the medium, ensuring it remains moist. Eventually plantlets will begin to grow.

When the plantlets have formed at least several leaves and a root system, gently remove them from the leaf. Plant each plantlet in a small pot filled with moist, well-draining potting medium. Allow the plant to grow on, caring for it as you would a larger Rex begonia.

When sited in the correct position the colors and pattern of the plant’s leaves becomes more intense. Finding the correct position is also key to successfully growing begonias. 

Rex begonia has a reputation for being difficult but their eye-catching foliage means that they are well worth the effort. Like other houseplants, such as Christmas Cacti or African Violets, once you know how to care for a Rex Begonia plant they are pleasingly easy to grow. Best grown in containers or as houseplants, this is a stunning way to add interest and color to your home.