Rex begonia plants with their large, colorful leaves help make them perfect indoor plants for the window garden.
Pronounced [reks be-GON-yuh], the plant is sometimes called the painted-leaf begonia.
People often refer to ‘REX” it as the “showboat” and ‘King of the Begonias” world due to the multi-colored leaves.
While rex begonias, are widely available, there are hundreds of hybrids available of the (Begonia Rex-cultorum group) since the initial discovery of the species in northern Assam, India in 1858.
These rhizomatous begonia plants are typically grown as houseplants or summer outdoor plants.
They are considered a difficult tropical plant to cultivate but is worth the effort, thanks to the showy leaves.
Rex Begonia Care
Size and Growth
Rex begonias may reach a height of 10″ to 26″ inches. It produces oval or heart-shaped fancy leaved begonias with interesting coloration.
The leaves are large and multicolored. The outer edges of the leaf may appear dark green while the inner parts are a mixture of pink and white.
Shades of red, purple, bronze, black, and silver may also appear.
The leaves are often six to 12 inches across. While it’s an evergreen plant, it may shed several leaves during the colder months.
Flowering and Fragrance
Although the painted-leaf begonia is a flowering plant it is not grown for its flowers as the leaves are much more attractive.
In the middle of summer, it may produce a cluster of small pink flowers.
While the flowers are lovely, they take nutrients from the plant, weakening the leaves.
Removing the flowers when they appear helps keep the leaves healthy.
Light and Temperature
In USDA hardiness zones 10 and 11, the plant can grow outdoors year-round, enjoying the heat of the summer.
In cooler areas, plants can be brought outdoors in the summer and placed indoors in the fall.
Some people find that the plant is difficult to care for, struggling to find the right balance of light and temperature.
The ideal summer temperature is 74° degrees Fahrenheit while the perfect winter months temperature is 64 degrees Fahrenheit.
The plant needs plenty of bright indirect light but not direct sun. The bright UV rays may scorch the leaves.
The painted-leaf begonia also likes high humidity. Try to maintain a relative humidity reading above 50%.
Light misting may be needed as most homes have humidity levels between 30% and 40%.
Learn more on growing Rex Begonias under artificial lights
Watering and Feeding
Water frequently throughout the summer, ensuring that the soil never dries out completely. In the winter, water the plant sparingly.
The painted-leaf begonia doesn’t need plant food in the winter but benefits from diluted water fertilizer during the active growing season. Feed once per month during spring and summer.
Soil and Transplanting
When growing Rex use a rich potting mix with fast drainage. It should remain moist but not soggy.
Transplanting may be needed if the plant outgrows its container.
Otherwise, leave it in place and freshen the topsoil.
Repot in the spring in shallow pots, which is also the best time to propagate.
Large, shallow pots allow the rhizomes to spread.
Maintenance and Grooming
Remove withered or dead leaves to keep plants looking good and encourage new growth.
As mentioned, the flowers may take nutrients from the plant. When the flowers appear, remove them.
How To Propagate Rex Begonias
Propagation is possible from:
- Stem cuttings
- Leaf cuttings
- Sections of rhizomes
At the start of spring, cut off an entire leave, a rhizome, or a portion of stalk containing one or two leaves.
Use a combination of perlite and peat moss for the potting soil.
Ensure that the soil is evenly moist
Plant the cutting or rhizomes in the soil.
Cover the containers with plastic and cut holes for ventilation.
Keep the plant at a temperature, between 75° degrees and 78° degrees Fahrenheit.
The new plants should start to grow roots in about three to four weeks.
After the roots appear firm and the plant grows two or three new leaves, transplant the young plants into their own containers.
Rex Begonia Pests or Diseases
There is a wide range of disease problems to pay attention to, including:
- Root Rot
- Dried leaves
- Stunted growth
- Powdery Mildew
- Gray Mold
Root rot is often caused by too much water – overwatering. Trim rotted parts away and reduce watering.
Dried leaf tips indicate underwatering. Keep the soil moist but not soggy and remove the withered leaves.
Dry brittle leaves indicate low humidity and dry air. Provide more humidity and good air circulation.
Stunted growth typically occurs due to a lack of nutrient in the soil.
The begonia plant craves a nutrient-rich potting mix like a peat moss based African violet mix.
Use liquid plant food once per week and then transplant the plant in the spring.
Powdery mildew appears as white deposits on the stems and leaves.
Slightly reduce watering and move the plant to a brighter location after trimming away the infected areas.
Gray or brown patches indicate gray mold. Brighter light and less humidity may solve the issue. For severe mold, use a fungicide.
Uses For Rex Begonias
In warm regions, the short rex begonias look great under larger plants and make beautiful hanging baskets in the shade.
In cooler areas, the rex plant is often grown indoors as house plants in shallow pots under fluorescent lights, making it easier to enjoy and move plants to different areas in the home throughout the year.