Often seen as a high-maintenance and fussy plant, Rex Begonias are grown for their amazingly bright and colorful foliage as well as their often interesting leaf shapes. Even though they are on the high-maintenance side, they are well worth the effort.
Background
Rex Begonia is a species of plant native to Asia and is popularly kept as a houseplant around the world due to its unmatched variety of bright, glistening foliage. Rex Begonia is also sometimes referred to as ‘Painted-Leaf Begonia’.
Growing Conditions
Light
Bright indirect light. Direct sun might be alright in the colder months. Can also tolerate medium light. They enter dormancy in winter if they don’t receive enough light. (Maybe use a grow light?) Leaves will start dropping but this does not necessarily mean that the plant is dead. Just reduce the frequency that you water the plant, and wait for new leaf group in Spring.
Watering
It’s best to let Rex Begonias slightly dry out between waterings. When you do water, you should water them thoroughly. However, don’t ever let the soil completely dry out. If your tap water is hard instead of soft, distilled water might be better instead. Avoid wetting the foliage of Rex Begonias, this can cause powdery mildew or other problems.
Potting Mix
Needs a very well-draining potting mix. Don’t go for just any all-purpose commercial mix, make sure it is a well-draining mix. You could add some perlite or pumice to a regular potting mix to achieve this increased aeration. Cactus potting mix would be a little too well-draining — avoid those for Rex Begonias. Root rot can be common with Rex Begonias if the potting media is left overly moist. Hence why a well-draining mix is necessary.
Humidity
Humidity around 55% or more if possible. Never mist the plant though. For some people, a terrarium might be the only place they can successfully grow a Rex Begonia indoors.
Fertilizer
Fertilizing once a month will be just fine. Stop fertilization during the colder months.
Propagation
Rex Begonias are propagated via leaf cuttings.
Potential Problems
Removing dead leaves will help with preventing pests. Browning leaf edges are usually either caused by low humidity (which is a common problem with this species indoors) or because the potting media is drying out too much and the plant isn’t receiving enough water.