Rex begonias are an amazingly diverse group of plants with gorgeous foliage and flowers.
There are at least 4,161 cultivars of rex begonias, ensuring there’s a punch in for every garden.
All parts of rex begonias are toxic to dogs, cats, and horses.
Credit:Denny Schrock
Outdoors, rex begonias can be planted in containers in bright or shady spots in regions with ample humidity.
Indoors, these begonias do well in east-facing locations or south-facing windows just outside direct sun.
Keep the begonias far away from fans, heaters, and air conditioners.
Credit:Lynn Karlin
Begonias can be moved outdoors during the summer months while temperatures remain above 60F and humidity is high.
Rex begonias are not cold or frost-tolerant and will quickly die back after even a light frost.
Plant the rhizomes inwell-draining potting soil, adding compost or perlite to improve drainage.
Credit:Denny Schrock
Plant rex begonias close together to allow them to trap their own moisture and stay healthy.
Outdoors, morning sun or dappled light under a tree is preferred.
Use a quick-draining soil oradd perlite, sand, or small bark chipsto aid drainage.
Credit: Justin Hancock
While drainage is essential, rex begonias prefer constant moisture with slight drying between waterings during their growing season.
Water your begonia thoroughlyand allow any excess to drain away from the roots.
Temperature and Humidity
Rex begonias prefer temperatures similar to those people enjoy,making them great houseplants.
Daytime temperatures in the 70s or low 80s and temperatures decreasing by about 10F at night are ideal.
Humidity is key to keeping begonia leaves full and unblemished by unsightly brown edges and deformities.
Keep humidity above 50% throughout the growing season.
Potting and Repotting Rex Begonias
When potting rex begonias, use aceramic or terra-cotta potwith drainage holes.
Fill it with a quick-draining soil or add perlite to commercial potting soil.
The container should be only 2-3 inches wider than the plant’s root ball.
Your begonia can stay in the container as long as the rhizome isn’t touching the sides.
Indoors, mealybugs are among themost common houseplant pestsaffecting rex begonias.
Isolate infested plants and manually remove the insects with a fingertip or cotton swab.
Next,spray the plant with neem oilor insecticidal soap.
Multiple applications may be necessary to eliminate mealybugs and other pests.
Root rot is a common problem for many begonia species and hybrids.
To avoid root rot, plant begonias in loamy soil with excellent drainage.
Planting in terra-cotta clay pots can also help to avoid overwatering.
How to Propagate Rex Begonias
Rex begonias are relativelyeasy to propagate through leaf cuttings and division.
Leaf Cuttings:
New plants begin to form in about three to four weeks.
Be patient, as this process can take quite a while.
New plants will form leaves, rhizomes, and roots.
The plantlets can be divided and planted in individual containers at this stage.
Divisions:Turn one rex begonia into two bydividing the rhizomes.
Remove the plant from its container and use your hands to pull the rhizomes and roots apart.
Immediately replant the two sections in containers filled with potting soil.
These plants can be divided at any time of year, but they respond more slowly in the winter.
It grows 6-12 inches tall and wide.
‘Fireworks’ Rex Begonia
Begonia rex’Fireworks' is another exceptionally colorful plant.
‘Fireworks’ produces heavily textured leaves with deep plum purple, green, and silver.
It grows 10-16 inches tall and 18 inches wide.
It grows 8-12 inches tall and spreads 15-18 inches wide.
Any seeds planted will more than likely be different from the parent plants.
They can grow 12-24 inches over several years.
