How To Care For A Rex Begonia Plant. The potting medium for rex begonias should have well-draining soil that is light and rich. Avoid any heavy potting mixes.
Consider housing your Rex Begonia inside of a glass cloche or a Wardian case to maintain high levels of humidity. This is important to keep the foliage growing healthy although it is sometimes difficult to achieve indoors. Which makes using fast-draining soil super important.
This can be done while repotting the plant or at any other time by just gently pulling the rhizomes apart and repotting all of them into their own container.
Also avoid allowing your rex begonias leaves to be wet for extended periods of time especially at night since this can encourage powdery mildew as well as bacteria leaf spot. You can also use a slow-release all-purpose formula applied every three months. If your Rex Begonia leaves are crispy or brittle chances are the air in your home is too dry for this type of plant. Over handling can cause the plants stress and in the worst cases can cause them to die.